diff options
| -rw-r--r-- | arch/x86/include/asm/nospec-branch.h | 2 | ||||
| -rw-r--r-- | arch/x86/include/asm/processor.h | 1 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/bugs.c | 1183 | ||||
| -rw-r--r-- | arch/x86/kvm/vmx/vmx.c | 8 |
4 files changed, 684 insertions, 510 deletions
diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h index 5c43f145454d..81c4a13e4c0d 100644 --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -561,7 +561,7 @@ DECLARE_STATIC_KEY_FALSE(mds_idle_clear); DECLARE_STATIC_KEY_FALSE(switch_mm_cond_l1d_flush); -DECLARE_STATIC_KEY_FALSE(mmio_stale_data_clear); +DECLARE_STATIC_KEY_FALSE(cpu_buf_vm_clear); extern u16 mds_verw_sel; diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 5d2f7e5aff26..0973bed22172 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -734,6 +734,7 @@ void store_cpu_caps(struct cpuinfo_x86 *info); enum l1tf_mitigations { L1TF_MITIGATION_OFF, + L1TF_MITIGATION_AUTO, L1TF_MITIGATION_FLUSH_NOWARN, L1TF_MITIGATION_FLUSH, L1TF_MITIGATION_FLUSH_NOSMT, diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 362602b705cc..a4f3b1d03406 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -34,21 +34,63 @@ #include "cpu.h" +/* + * Speculation Vulnerability Handling + * + * Each vulnerability is handled with the following functions: + * <vuln>_select_mitigation() -- Selects a mitigation to use. This should + * take into account all relevant command line + * options. + * <vuln>_update_mitigation() -- This is called after all vulnerabilities have + * selected a mitigation, in case the selection + * may want to change based on other choices + * made. This function is optional. + * <vuln>_apply_mitigation() -- Enable the selected mitigation. + * + * The compile-time mitigation in all cases should be AUTO. An explicit + * command-line option can override AUTO. If no such option is + * provided, <vuln>_select_mitigation() will override AUTO to the best + * mitigation option. + */ + static void __init spectre_v1_select_mitigation(void); +static void __init spectre_v1_apply_mitigation(void); static void __init spectre_v2_select_mitigation(void); +static void __init spectre_v2_update_mitigation(void); +static void __init spectre_v2_apply_mitigation(void); static void __init retbleed_select_mitigation(void); +static void __init retbleed_update_mitigation(void); +static void __init retbleed_apply_mitigation(void); static void __init spectre_v2_user_select_mitigation(void); +static void __init spectre_v2_user_update_mitigation(void); +static void __init spectre_v2_user_apply_mitigation(void); static void __init ssb_select_mitigation(void); +static void __init ssb_apply_mitigation(void); static void __init l1tf_select_mitigation(void); +static void __init l1tf_apply_mitigation(void); static void __init mds_select_mitigation(void); -static void __init md_clear_update_mitigation(void); -static void __init md_clear_select_mitigation(void); +static void __init mds_update_mitigation(void); +static void __init mds_apply_mitigation(void); static void __init taa_select_mitigation(void); +static void __init taa_update_mitigation(void); +static void __init taa_apply_mitigation(void); static void __init mmio_select_mitigation(void); +static void __init mmio_update_mitigation(void); +static void __init mmio_apply_mitigation(void); +static void __init rfds_select_mitigation(void); +static void __init rfds_update_mitigation(void); +static void __init rfds_apply_mitigation(void); static void __init srbds_select_mitigation(void); +static void __init srbds_apply_mitigation(void); static void __init l1d_flush_select_mitigation(void); static void __init srso_select_mitigation(void); +static void __init srso_update_mitigation(void); +static void __init srso_apply_mitigation(void); static void __init gds_select_mitigation(void); +static void __init gds_apply_mitigation(void); +static void __init bhi_select_mitigation(void); +static void __init bhi_update_mitigation(void); +static void __init bhi_apply_mitigation(void); /* The base value of the SPEC_CTRL MSR without task-specific bits set */ u64 x86_spec_ctrl_base; @@ -127,9 +169,13 @@ EXPORT_SYMBOL_GPL(mds_idle_clear); */ DEFINE_STATIC_KEY_FALSE(switch_mm_cond_l1d_flush); -/* Controls CPU Fill buffer clear before KVM guest MMIO accesses */ -DEFINE_STATIC_KEY_FALSE(mmio_stale_data_clear); -EXPORT_SYMBOL_GPL(mmio_stale_data_clear); +/* + * Controls CPU Fill buffer clear before VMenter. This is a subset of + * X86_FEATURE_CLEAR_CPU_BUF, and should only be enabled when KVM-only + * mitigation is required. + */ +DEFINE_STATIC_KEY_FALSE(cpu_buf_vm_clear); +EXPORT_SYMBOL_GPL(cpu_buf_vm_clear); void __init cpu_select_mitigations(void) { @@ -154,30 +200,60 @@ void __init cpu_select_mitigations(void) /* Select the proper CPU mitigations before patching alternatives: */ spectre_v1_select_mitigation(); spectre_v2_select_mitigation(); - /* - * retbleed_select_mitigation() relies on the state set by - * spectre_v2_select_mitigation(); specifically it wants to know about - * spectre_v2=ibrs. - */ retbleed_select_mitigation(); - /* - * spectre_v2_user_select_mitigation() relies on the state set by - * retbleed_select_mitigation(); specifically the STIBP selection is - * forced for UNRET or IBPB. - */ spectre_v2_user_select_mitigation(); ssb_select_mitigation(); l1tf_select_mitigation(); - md_clear_select_mitigation(); + mds_select_mitigation(); + taa_select_mitigation(); + mmio_select_mitigation(); + rfds_select_mitigation(); srbds_select_mitigation(); l1d_flush_select_mitigation(); + srso_select_mitigation(); + gds_select_mitigation(); + bhi_select_mitigation(); /* - * srso_select_mitigation() depends and must run after - * retbleed_select_mitigation(). + * After mitigations are selected, some may need to update their + * choices. */ - srso_select_mitigation(); - gds_select_mitigation(); + spectre_v2_update_mitigation(); + /* + * retbleed_update_mitigation() relies on the state set by + * spectre_v2_update_mitigation(); specifically it wants to know about + * spectre_v2=ibrs. + */ + retbleed_update_mitigation(); + + /* + * spectre_v2_user_update_mitigation() depends on + * retbleed_update_mitigation(), specifically the STIBP + * selection is forced for UNRET or IBPB. + */ + spectre_v2_user_update_mitigation(); + mds_update_mitigation(); + taa_update_mitigation(); + mmio_update_mitigation(); + rfds_update_mitigation(); + bhi_update_mitigation(); + /* srso_update_mitigation() depends on retbleed_update_mitigation(). */ + srso_update_mitigation(); + + spectre_v1_apply_mitigation(); + spectre_v2_apply_mitigation(); + retbleed_apply_mitigation(); + spectre_v2_user_apply_mitigation(); + ssb_apply_mitigation(); + l1tf_apply_mitigation(); + mds_apply_mitigation(); + taa_apply_mitigation(); + mmio_apply_mitigation(); + rfds_apply_mitigation(); + srbds_apply_mitigation(); + srso_apply_mitigation(); + gds_apply_mitigation(); + bhi_apply_mitigation(); } /* @@ -280,6 +356,12 @@ enum rfds_mitigations { static enum rfds_mitigations rfds_mitigation __ro_after_init = IS_ENABLED(CONFIG_MITIGATION_RFDS) ? RFDS_MITIGATION_AUTO : RFDS_MITIGATION_OFF; +/* + * Set if any of MDS/TAA/MMIO/RFDS are going to enable VERW clearing + * through X86_FEATURE_CLEAR_CPU_BUF on kernel and guest entry. + */ +static bool verw_clear_cpu_buf_mitigation_selected __ro_after_init; + static void __init mds_select_mitigation(void) { if (!boot_cpu_has_bug(X86_BUG_MDS) || cpu_mitigations_off()) { @@ -290,12 +372,34 @@ static void __init mds_select_mitigation(void) if (mds_mitigation == MDS_MITIGATION_AUTO) mds_mitigation = MDS_MITIGATION_FULL; + if (mds_mitigation == MDS_MITIGATION_OFF) + return; + + verw_clear_cpu_buf_mitigation_selected = true; +} + +static void __init mds_update_mitigation(void) +{ + if (!boot_cpu_has_bug(X86_BUG_MDS) || cpu_mitigations_off()) + return; + + /* If TAA, MMIO, or RFDS are being mitigated, MDS gets mitigated too. */ + if (verw_clear_cpu_buf_mitigation_selected) + mds_mitigation = MDS_MITIGATION_FULL; + if (mds_mitigation == MDS_MITIGATION_FULL) { if (!boot_cpu_has(X86_FEATURE_MD_CLEAR)) mds_mitigation = MDS_MITIGATION_VMWERV; + } - setup_force_cpu_cap(X86_FEATURE_CLEAR_CPU_BUF); + pr_info("%s\n", mds_strings[mds_mitigation]); +} +static void __init mds_apply_mitigation(void) +{ + if (mds_mitigation == MDS_MITIGATION_FULL || + mds_mitigation == MDS_MITIGATION_VMWERV) { + setup_force_cpu_cap(X86_FEATURE_CLEAR_CPU_BUF); if (!boot_cpu_has(X86_BUG_MSBDS_ONLY) && (mds_nosmt || cpu_mitigations_auto_nosmt())) cpu_smt_disable(false); @@ -335,6 +439,11 @@ static const char * const taa_strings[] = { [TAA_MITIGATION_TSX_DISABLED] = "Mitigation: TSX disabled", }; +static bool __init taa_vulnerable(void) +{ + return boot_cpu_has_bug(X86_BUG_TAA) && boot_cpu_has(X86_FEATURE_RTM); +} + static void __init taa_select_mitigation(void) { if (!boot_cpu_has_bug(X86_BUG_TAA)) { @@ -348,48 +457,63 @@ static void __init taa_select_mitigation(void) return; } - if (cpu_mitigations_off()) { + if (cpu_mitigations_off()) taa_mitigation = TAA_MITIGATION_OFF; - return; - } - /* - * TAA mitigation via VERW is turned off if both - * tsx_async_abort=off and mds=off are specified. - */ - if (taa_mitigation == TAA_MITIGATION_OFF && - mds_mitigation == MDS_MITIGATION_OFF) + /* Microcode will be checked in taa_update_mitigation(). */ + if (taa_mitigation == TAA_MITIGATION_AUTO) + taa_mitigation = TAA_MITIGATION_VERW; + + if (taa_mitigation != TAA_MITIGATION_OFF) + verw_clear_cpu_buf_mitigation_selected = true; +} + +static void __init taa_update_mitigation(void) +{ + if (!taa_vulnerable() || cpu_mitigations_off()) return; - if (boot_cpu_has(X86_FEATURE_MD_CLEAR)) + if (verw_clear_cpu_buf_mitigation_selected) taa_mitigation = TAA_MITIGATION_VERW; - else - taa_mitigation = TAA_MITIGATION_UCODE_NEEDED; - /* - * VERW doesn't clear the CPU buffers when MD_CLEAR=1 and MDS_NO=1. - * A microcode update fixes this behavior to clear CPU buffers. It also - * adds support for MSR_IA32_TSX_CTRL which is enumerated by the - * ARCH_CAP_TSX_CTRL_MSR bit. - * - * On MDS_NO=1 CPUs if ARCH_CAP_TSX_CTRL_MSR is not set, microcode - * update is required. - */ - if ( (x86_arch_cap_msr & ARCH_CAP_MDS_NO) && - !(x86_arch_cap_msr & ARCH_CAP_TSX_CTRL_MSR)) - taa_mitigation = TAA_MITIGATION_UCODE_NEEDED; + if (taa_mitigation == TAA_MITIGATION_VERW) { + /* Check if the requisite ucode is available. */ + if (!boot_cpu_has(X86_FEATURE_MD_CLEAR)) + taa_mitigation = TAA_MITIGATION_UCODE_NEEDED; - /* - * TSX is enabled, select alternate mitigation for TAA which is - * the same as MDS. Enable MDS static branch to clear CPU buffers. - * - * For guests that can't determine whether the correct microcode is - * present on host, enable the mitigation for UCODE_NEEDED as well. - */ - setup_force_cpu_cap(X86_FEATURE_CLEAR_CPU_BUF); + /* + * VERW doesn't clear the CPU buffers when MD_CLEAR=1 and MDS_NO=1. + * A microcode update fixes this behavior to clear CPU buffers. It also + * adds support for MSR_IA32_TSX_CTRL which is enumerated by the + * ARCH_CAP_TSX_CTRL_MSR bit. + * + * On MDS_NO=1 CPUs if ARCH_CAP_TSX_CTRL_MSR is not set, microcode + * update is required. + */ + if ((x86_arch_cap_msr & ARCH_CAP_MDS_NO) && + !(x86_arch_cap_msr & ARCH_CAP_TSX_CTRL_MSR)) + taa_mitigation = TAA_MITIGATION_UCODE_NEEDED; + } - if (taa_nosmt || cpu_mitigations_auto_nosmt()) - cpu_smt_disable(false); + pr_info("%s\n", taa_strings[taa_mitigation]); +} + +static void __init taa_apply_mitigation(void) +{ + if (taa_mitigation == TAA_MITIGATION_VERW || + taa_mitigation == TAA_MITIGATION_UCODE_NEEDED) { + /* + * TSX is enabled, select alternate mitigation for TAA which is + * the same as MDS. Enable MDS static branch to clear CPU buffers. + * + * For guests that can't determine whether the correct microcode is + * present on host, enable the mitigation for UCODE_NEEDED as well. + */ + setup_force_cpu_cap(X86_FEATURE_CLEAR_CPU_BUF); + + if (taa_nosmt || cpu_mitigations_auto_nosmt()) + cpu_smt_disable(false); + } } static int __init tsx_async_abort_parse_cmdline(char *str) @@ -433,25 +557,62 @@ static void __init mmio_select_mitigation(void) return; } + /* Microcode will be checked in mmio_update_mitigation(). */ + if (mmio_mitigation == MMIO_MITIGATION_AUTO) + mmio_mitigation = MMIO_MITIGATION_VERW; + if (mmio_mitigation == MMIO_MITIGATION_OFF) return; /* * Enable CPU buffer clear mitigation for host and VMM, if also affected - * by MDS or TAA. Otherwise, enable mitigation for VMM only. + * by MDS or TAA. */ - if (boot_cpu_has_bug(X86_BUG_MDS) || (boot_cpu_has_bug(X86_BUG_TAA) && - boot_cpu_has(X86_FEATURE_RTM))) - setup_force_cpu_cap(X86_FEATURE_CLEAR_CPU_BUF); + if (boot_cpu_has_bug(X86_BUG_MDS) || taa_vulnerable()) + verw_clear_cpu_buf_mitigation_selected = true; +} + +static void __init mmio_update_mitigation(void) +{ + if (!boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA) || cpu_mitigations_off()) + return; + + if (verw_clear_cpu_buf_mitigation_selected) + mmio_mitigation = MMIO_MITIGATION_VERW; + + if (mmio_mitigation == MMIO_MITIGATION_VERW) { + /* + * Check if the system has the right microcode. + * + * CPU Fill buffer clear mitigation is enumerated by either an explicit + * FB_CLEAR or by the presence of both MD_CLEAR and L1D_FLUSH on MDS + * affected systems. + */ + if (!((x86_arch_cap_msr & ARCH_CAP_FB_CLEAR) || + (boot_cpu_has(X86_FEATURE_MD_CLEAR) && + boot_cpu_has(X86_FEATURE_FLUSH_L1D) && + !(x86_arch_cap_msr & ARCH_CAP_MDS_NO)))) + mmio_mitigation = MMIO_MITIGATION_UCODE_NEEDED; + } + + pr_info("%s\n", mmio_strings[mmio_mitigation]); +} + +static void __init mmio_apply_mitigation(void) +{ + if (mmio_mitigation == MMIO_MITIGATION_OFF) + return; /* - * X86_FEATURE_CLEAR_CPU_BUF could be enabled by other VERW based - * mitigations, disable KVM-only mitigation in that case. + * Only enable the VMM mitigation if the CPU buffer clear mitigation is + * not being used. */ - if (boot_cpu_has(X86_FEATURE_CLEAR_CPU_BUF)) - static_branch_disable(&mmio_stale_data_clear); - else - static_branch_enable(&mmio_stale_data_clear); + if (verw_clear_cpu_buf_mitigation_selected) { + setup_force_cpu_cap(X86_FEATURE_CLEAR_CPU_BUF); + static_branch_disable(&cpu_buf_vm_clear); + } else { + static_branch_enable(&cpu_buf_vm_clear); + } /* * If Processor-MMIO-Stale-Data bug is present and Fill Buffer data can @@ -461,21 +622,6 @@ static void __init mmio_select_mitigation(void) if (!(x86_arch_cap_msr & ARCH_CAP_FBSDP_NO)) static_branch_enable(&mds_idle_clear); - /* - * Check if the system has the right microcode. - * - * CPU Fill buffer clear mitigation is enumerated by either an explicit - * FB_CLEAR or by the presence of both MD_CLEAR and L1D_FLUSH on MDS - * affected systems. - */ - if ((x86_arch_cap_msr & ARCH_CAP_FB_CLEAR) || - (boot_cpu_has(X86_FEATURE_MD_CLEAR) && - boot_cpu_has(X86_FEATURE_FLUSH_L1D) && - !(x86_arch_cap_msr & ARCH_CAP_MDS_NO))) - mmio_mitigation = MMIO_MITIGATION_VERW; - else - mmio_mitigation = MMIO_MITIGATION_UCODE_NEEDED; - if (mmio_nosmt || cpu_mitigations_auto_nosmt()) cpu_smt_disable(false); } @@ -510,22 +656,48 @@ static const char * const rfds_strings[] = { [RFDS_MITIGATION_UCODE_NEEDED] = "Vulnerable: No microcode", }; +static inline bool __init verw_clears_cpu_reg_file(void) +{ + return (x86_arch_cap_msr & ARCH_CAP_RFDS_CLEAR); +} + static void __init rfds_select_mitigation(void) { if (!boot_cpu_has_bug(X86_BUG_RFDS) || cpu_mitigations_off()) { rfds_mitigation = RFDS_MITIGATION_OFF; return; } + + if (rfds_mitigation == RFDS_MITIGATION_AUTO) + rfds_mitigation = RFDS_MITIGATION_VERW; + if (rfds_mitigation == RFDS_MITIGATION_OFF) return; - if (rfds_mitigation == RFDS_MITIGATION_AUTO) + if (verw_clears_cpu_reg_file()) + verw_clear_cpu_buf_mitigation_selected = true; +} + +static void __init rfds_update_mitigation(void) +{ + if (!boot_cpu_has_bug(X86_BUG_RFDS) || cpu_mitigations_off()) + return; + + if (verw_clear_cpu_buf_mitigation_selected) rfds_mitigation = RFDS_MITIGATION_VERW; - if (x86_arch_cap_msr & ARCH_CAP_RFDS_CLEAR) + if (rfds_mitigation == RFDS_MITIGATION_VERW) { + if (!verw_clears_cpu_reg_file()) + rfds_mitigation = RFDS_MITIGATION_UCODE_NEEDED; + } + + pr_info("%s\n", rfds_strings[rfds_mitigation]); +} + +static void __init rfds_apply_mitigation(void) +{ + if (rfds_mitigation == RFDS_MITIGATION_VERW) setup_force_cpu_cap(X86_FEATURE_CLEAR_CPU_BUF); - else - rfds_mitigation = RFDS_MITIGATION_UCODE_NEEDED; } static __init int rfds_parse_cmdline(char *str) @@ -546,76 +718,11 @@ static __init int rfds_parse_cmdline(char *str) early_param("reg_file_data_sampling", rfds_parse_cmdline); #undef pr_fmt -#define pr_fmt(fmt) "" fmt - -static void __init md_clear_update_mitigation(void) -{ - if (cpu_mitigations_off()) - return; - - if (!boot_cpu_has(X86_FEATURE_CLEAR_CPU_BUF)) - goto out; - - /* - * X86_FEATURE_CLEAR_CPU_BUF is now enabled. Update MDS, TAA and MMIO - * Stale Data mitigation, if necessary. - */ - if (mds_mitigation == MDS_MITIGATION_OFF && - boot_cpu_has_bug(X86_BUG_MDS)) { - mds_mitigation = MDS_MITIGATION_FULL; - mds_select_mitigation(); - } - if (taa_mitigation == TAA_MITIGATION_OFF && - boot_cpu_has_bug(X86_BUG_TAA)) { - taa_mitigation = TAA_MITIGATION_VERW; - taa_select_mitigation(); - } - /* - * MMIO_MITIGATION_OFF is not checked here so that mmio_stale_data_clear - * gets updated correctly as per X86_FEATURE_CLEAR_CPU_BUF state. - */ - if (boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA)) { - mmio_mitigation = MMIO_MITIGATION_VERW; - mmio_select_mitigation(); - } - if (rfds_mitigation == RFDS_MITIGATION_OFF && - boot_cpu_has_bug(X86_BUG_RFDS)) { - rfds_mitigation = RFDS_MITIGATION_VERW; - rfds_select_mitigation(); - } -out: - if (boot_cpu_has_bug(X86_BUG_MDS)) - pr_info("MDS: %s\n", mds_strings[mds_mitigation]); - if (boot_cpu_has_bug(X86_BUG_TAA)) - pr_info("TAA: %s\n", taa_strings[taa_mitigation]); - if (boot_cpu_has_bug(X86_BUG_MMIO_STALE_DATA)) - pr_info("MMIO Stale Data: %s\n", mmio_strings[mmio_mitigation]); - else if (boot_cpu_has_bug(X86_BUG_MMIO_UNKNOWN)) - pr_info("MMIO Stale Data: Unknown: No mitigations\n"); - if (boot_cpu_has_bug(X86_BUG_RFDS)) - pr_info("Register File Data Sampling: %s\n", rfds_strings[rfds_mitigation]); -} - -static void __init md_clear_select_mitigation(void) -{ - mds_select_mitigation(); - taa_select_mitigation(); - mmio_select_mitigation(); - rfds_select_mitigation(); - - /* - * As these mitigations are inter-related and rely on VERW instruction - * to clear the microarchitural buffers, update and print their status - * after mitigation selection is done for each of these vulnerabilities. - */ - md_clear_update_mitigation(); -} - -#undef pr_fmt #define pr_fmt(fmt) "SRBDS: " fmt enum srbds_mitigations { SRBDS_MITIGATION_OFF, + SRBDS_MITIGATION_AUTO, SRBDS_MITIGATION_UCODE_NEEDED, SRBDS_MITIGATION_FULL, SRBDS_MITIGATION_TSX_OFF, @@ -623,7 +730,7 @@ enum srbds_mitigations { }; static enum srbds_mitigations srbds_mitigation __ro_after_init = - IS_ENABLED(CONFIG_MITIGATION_SRBDS) ? SRBDS_MITIGATION_FULL : SRBDS_MITIGATION_OFF; + IS_ENABLED(CONFIG_MITIGATION_SRBDS) ? SRBDS_MITIGATION_AUTO : SRBDS_MITIGATION_OFF; static const char * const srbds_strings[] = { [SRBDS_MITIGATION_OFF] = "Vulnerable", @@ -674,8 +781,13 @@ void update_srbds_msr(void) static void __init srbds_select_mitigation(void) { - if (!boot_cpu_has_bug(X86_BUG_SRBDS)) + if (!boot_cpu_has_bug(X86_BUG_SRBDS) || cpu_mitigations_off()) { + srbds_mitigation = SRBDS_MITIGATION_OFF; return; + } + + if (srbds_mitigation == SRBDS_MITIGATION_AUTO) + srbds_mitigation = SRBDS_MITIGATION_FULL; /* * Check to see if this is one of the MDS_NO systems supporting TSX that @@ -689,13 +801,17 @@ static void __init srbds_select_mitigation(void) srbds_mitigation = SRBDS_MITIGATION_HYPERVISOR; else if (!boot_cpu_has(X86_FEATURE_SRBDS_CTRL)) srbds_mitigation = SRBDS_MITIGATION_UCODE_NEEDED; - else if (cpu_mitigations_off() || srbds_off) + else if (srbds_off) srbds_mitigation = SRBDS_MITIGATION_OFF; - update_srbds_msr(); pr_info("%s\n", srbds_strings[srbds_mitigation]); } +static void __init srbds_apply_mitigation(void) +{ + update_srbds_msr(); +} + static int __init srbds_parse_cmdline(char *str) { if (!str) @@ -742,6 +858,7 @@ early_param("l1d_flush", l1d_flush_parse_cmdline); enum gds_mitigations { GDS_MITIGATION_OFF, + GDS_MITIGATION_AUTO, GDS_MITIGATION_UCODE_NEEDED, GDS_MITIGATION_FORCE, GDS_MITIGATION_FULL, @@ -750,7 +867,7 @@ enum gds_mitigations { }; static enum gds_mitigations gds_mitigation __ro_after_init = - IS_ENABLED(CONFIG_MITIGATION_GDS) ? GDS_MITIGATION_FULL : GDS_MITIGATION_OFF; + IS_ENABLED(CONFIG_MITIGATION_GDS) ? GDS_MITIGATION_AUTO : GDS_MITIGATION_OFF; static const char * const gds_strings[] = { [GDS_MITIGATION_OFF] = "Vulnerable", @@ -791,6 +908,7 @@ void update_gds_msr(void) case GDS_MITIGATION_FORCE: case GDS_MITIGATION_UCODE_NEEDED: case GDS_MITIGATION_HYPERVISOR: + case GDS_MITIGATION_AUTO: return; } @@ -814,26 +932,21 @@ static void __init gds_select_mitigation(void) if (boot_cpu_has(X86_FEATURE_HYPERVISOR)) { gds_mitigation = GDS_MITIGATION_HYPERVISOR; - goto out; + return; } if (cpu_mitigations_off()) gds_mitigation = GDS_MITIGATION_OFF; /* Will verify below that mitigation _can_ be disabled */ + if (gds_mitigation == GDS_MITIGATION_AUTO) + gds_mitigation = GDS_MITIGATION_FULL; + /* No microcode */ if (!(x86_arch_cap_msr & ARCH_CAP_GDS_CTRL)) { - if (gds_mitigation == GDS_MITIGATION_FORCE) { - /* - * This only needs to be done on the boot CPU so do it - * here rather than in update_gds_msr() - */ - setup_clear_cpu_cap(X86_FEATURE_AVX); - pr_warn("Microcode update needed! Disabling AVX as mitigation.\n"); - } else { + if (gds_mitigation != GDS_MITIGATION_FORCE) gds_mitigation = GDS_MITIGATION_UCODE_NEEDED; - } - goto out; + return; } /* Microcode has mitigation, use it */ @@ -854,9 +967,25 @@ static void __init gds_select_mitigation(void) */ gds_mitigation = GDS_MITIGATION_FULL_LOCKED; } +} + +static void __init gds_apply_mitigation(void) +{ + if (!boot_cpu_has_bug(X86_BUG_GDS)) + return; + + /* Microcode is present */ + if (x86_arch_cap_msr & ARCH_CAP_GDS_CTRL) + update_gds_msr(); + else if (gds_mitigation == GDS_MITIGATION_FORCE) { + /* + * This only needs to be done on the boot CPU so do it + * here rather than in update_gds_msr() + */ + setup_clear_cpu_cap(X86_FEATURE_AVX); + pr_warn("Microcode update needed! Disabling AVX as mitigation.\n"); + } - update_gds_msr(); -out: pr_info("%s\n", gds_strings[gds_mitigation]); } @@ -917,10 +1046,14 @@ static bool smap_works_speculatively(void) static void __init spectre_v1_select_mitigation(void) { - if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V1) || cpu_mitigations_off()) { + if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V1) || cpu_mitigations_off()) spectre_v1_mitigation = SPECTRE_V1_MITIGATION_NONE; +} + +static void __init spectre_v1_apply_mitigation(void) +{ + if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V1) || cpu_mitigations_off()) return; - } if (spectre_v1_mitigation == SPECTRE_V1_MITIGATION_AUTO) { /* @@ -975,6 +1108,7 @@ enum spectre_v2_mitigation spectre_v2_enabled __ro_after_init = SPECTRE_V2_NONE; enum retbleed_mitigation { RETBLEED_MITIGATION_NONE, + RETBLEED_MITIGATION_AUTO, RETBLEED_MITIGATION_UNRET, RETBLEED_MITIGATION_IBPB, RETBLEED_MITIGATION_IBRS, @@ -982,14 +1116,6 @@ enum retbleed_mitigation { RETBLEED_MITIGATION_STUFF, }; -enum retbleed_mitigation_cmd { - RETBLEED_CMD_OFF, - RETBLEED_CMD_AUTO, - RETBLEED_CMD_UNRET, - RETBLEED_CMD_IBPB, - RETBLEED_CMD_STUFF, -}; - static const char * const retbleed_strings[] = { [RETBLEED_MITIGATION_NONE] = "Vulnerable", [RETBLEED_MITIGATION_UNRET] = "Mitigation: untrained return thunk", @@ -1000,9 +1126,7 @@ static const char * const retbleed_strings[] = { }; static enum retbleed_mitigation retbleed_mitigation __ro_after_init = - RETBLEED_MITIGATION_NONE; -static enum retbleed_mitigation_cmd retbleed_cmd __ro_after_init = - IS_ENABLED(CONFIG_MITIGATION_RETBLEED) ? RETBLEED_CMD_AUTO : RETBLEED_CMD_OFF; + IS_ENABLED(CONFIG_MITIGATION_RETBLEED) ? RETBLEED_MITIGATION_AUTO : RETBLEED_MITIGATION_NONE; static int __ro_after_init retbleed_nosmt = false; @@ -1019,15 +1143,15 @@ static int __init retbleed_parse_cmdline(char *str) } if (!strcmp(str, "off")) { - retbleed_cmd = RETBLEED_CMD_OFF; + retbleed_mitigation = RETBLEED_MITIGATION_NONE; } else if (!strcmp(str, "auto")) { - retbleed_cmd = RETBLEED_CMD_AUTO; + retbleed_mitigation = RETBLEED_MITIGATION_AUTO; } else if (!strcmp(str, "unret")) { - retbleed_cmd = RETBLEED_CMD_UNRET; + retbleed_mitigation = RETBLEED_MITIGATION_UNRET; } else if (!strcmp(str, "ibpb")) { - retbleed_cmd = RETBLEED_CMD_IBPB; + retbleed_mitigation = RETBLEED_MITIGATION_IBPB; } else if (!strcmp(str, "stuff")) { - retbleed_cmd = RETBLEED_CMD_STUFF; + retbleed_mitigation = RETBLEED_MITIGATION_STUFF; } else if (!strcmp(str, "nosmt")) { retbleed_nosmt = true; } else if (!strcmp(str, "force")) { @@ -1048,72 +1172,109 @@ early_param("retbleed", retbleed_parse_cmdline); static void __init retbleed_select_mitigation(void) { - bool mitigate_smt = false; - - if (!boot_cpu_has_bug(X86_BUG_RETBLEED) || cpu_mitigations_off()) - return; - - switch (retbleed_cmd) { - case RETBLEED_CMD_OFF: + if (!boot_cpu_has_bug(X86_BUG_RETBLEED) || cpu_mitigations_off()) { + retbleed_mitigation = RETBLEED_MITIGATION_NONE; return; + } - case RETBLEED_CMD_UNRET: - if (IS_ENABLED(CONFIG_MITIGATION_UNRET_ENTRY)) { - retbleed_mitigation = RETBLEED_MITIGATION_UNRET; - } else { + switch (retbleed_mitigation) { + case RETBLEED_MITIGATION_UNRET: + if (!IS_ENABLED(CONFIG_MITIGATION_UNRET_ENTRY)) { + retbleed_mitigation = RETBLEED_MITIGATION_AUTO; pr_err("WARNING: kernel not compiled with MITIGATION_UNRET_ENTRY.\n"); - goto do_cmd_auto; } break; - - case RETBLEED_CMD_IBPB: + case RETBLEED_MITIGATION_IBPB: if (!boot_cpu_has(X86_FEATURE_IBPB)) { pr_err("WARNING: CPU does not support IBPB.\n"); - goto do_cmd_auto; - } else if (IS_ENABLED(CONFIG_MITIGATION_IBPB_ENTRY)) { - retbleed_mitigation = RETBLEED_MITIGATION_IBPB; - } else { + retbleed_mitigation = RETBLEED_MITIGATION_AUTO; + } else if (!IS_ENABLED(CONFIG_MITIGATION_IBPB_ENTRY)) { pr_err("WARNING: kernel not compiled with MITIGATION_IBPB_ENTRY.\n"); - goto do_cmd_auto; + retbleed_mitigation = RETBLEED_MITIGATION_AUTO; } break; + case RETBLEED_MITIGATION_STUFF: + if (!IS_ENABLED(CONFIG_MITIGATION_CALL_DEPTH_TRACKING)) { + pr_err("WARNING: kernel not compiled with MITIGATION_CALL_DEPTH_TRACKING.\n"); + retbleed_mitigation = RETBLEED_MITIGATION_AUTO; + } else if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL) { + pr_err("WARNING: retbleed=stuff only supported for Intel CPUs.\n"); + retbleed_mitigation = RETBLEED_MITIGATION_AUTO; + } + break; + default: + break; + } - case RETBLEED_CMD_STUFF: - if (IS_ENABLED(CONFIG_MITIGATION_CALL_DEPTH_TRACKING) && - spectre_v2_enabled == SPECTRE_V2_RETPOLINE) { - retbleed_mitigation = RETBLEED_MITIGATION_STUFF; + if (retbleed_mitigation != RETBLEED_MITIGATION_AUTO) + return; - } else { - if (IS_ENABLED(CONFIG_MITIGATION_CALL_DEPTH_TRACKING)) - pr_err("WARNING: retbleed=stuff depends on spectre_v2=retpoline\n"); - else - pr_err("WARNING: kernel not compiled with MITIGATION_CALL_DEPTH_TRACKING.\n"); + /* Intel mitigation selected in retbleed_update_mitigation() */ + if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD || + boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) { + if (IS_ENABLED(CONFIG_MITIGATION_UNRET_ENTRY)) + retbleed_mitigation = RETBLEED_MITIGATION_UNRET; + else if (IS_ENABLED(CONFIG_MITIGATION_IBPB_ENTRY) && + boot_cpu_has(X86_FEATURE_IBPB)) + retbleed_mitigation = RETBLEED_MITIGATION_IBPB; + else + retbleed_mitigation = RETBLEED_MITIGATION_NONE; + } +} - goto do_cmd_auto; - } - break; +static void __init retbleed_update_mitigation(void) +{ + if (!boot_cpu_has_bug(X86_BUG_RETBLEED) || cpu_mitigations_off()) + return; + + if (retbleed_mitigation == RETBLEED_MITIGATION_NONE) + goto out; -do_cmd_auto: - case RETBLEED_CMD_AUTO: - if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD || - boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) { - if (IS_ENABLED(CONFIG_MITIGATION_UNRET_ENTRY)) - retbleed_mitigation = RETBLEED_MITIGATION_UNRET; - else if (IS_ENABLED(CONFIG_MITIGATION_IBPB_ENTRY) && - boot_cpu_has(X86_FEATURE_IBPB)) - retbleed_mitigation = RETBLEED_MITIGATION_IBPB; + /* + * retbleed=stuff is only allowed on Intel. If stuffing can't be used + * then a different mitigation will be selected below. + */ + if (retbleed_mitigation == RETBLEED_MITIGATION_STUFF) { + if (spectre_v2_enabled != SPECTRE_V2_RETPOLINE) { + pr_err("WARNING: retbleed=stuff depends on spectre_v2=retpoline\n"); + retbleed_mitigation = RETBLEED_MITIGATION_AUTO; } + } + /* + * Let IBRS trump all on Intel without affecting the effects of the + * retbleed= cmdline option except for call depth based stuffing + */ + if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) { + switch (spectre_v2_enabled) { + case SPECTRE_V2_IBRS: + retbleed_mitigation = RETBLEED_MITIGATION_IBRS; + break; + case SPECTRE_V2_EIBRS: + case SPECTRE_V2_EIBRS_RETPOLINE: + case SPECTRE_V2_EIBRS_LFENCE: + retbleed_mitigation = RETBLEED_MITIGATION_EIBRS; + break; + default: + if (retbleed_mitigation != RETBLEED_MITIGATION_STUFF) + pr_err(RETBLEED_INTEL_MSG); + } + /* If nothing has set the mitigation yet, default to NONE. */ + if (retbleed_mitigation == RETBLEED_MITIGATION_AUTO) + retbleed_mitigation = RETBLEED_MITIGATION_NONE; + } +out: + pr_info("%s\n", retbleed_strings[retbleed_mitigation]); +} - /* - * The Intel mitigation (IBRS or eIBRS) was already selected in - * spectre_v2_select_mitigation(). 'retbleed_mitigation' will - * be set accordingly below. - */ - break; - } +static void __init retbleed_apply_mitigation(void) +{ + bool mitigate_smt = false; switch (retbleed_mitigation) { + case RETBLEED_MITIGATION_NONE: + return; + case RETBLEED_MITIGATION_UNRET: setup_force_cpu_cap(X86_FEATURE_RETHUNK); setup_force_cpu_cap(X86_FEATURE_UNRET); @@ -1163,28 +1324,6 @@ do_cmd_auto: if (mitigate_smt && !boot_cpu_has(X86_FEATURE_STIBP) && (retbleed_nosmt || cpu_mitigations_auto_nosmt())) cpu_smt_disable(false); - - /* - * Let IBRS trump all on Intel without affecting the effects of the - * retbleed= cmdline option except for call depth based stuffing - */ - if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) { - switch (spectre_v2_enabled) { - case SPECTRE_V2_IBRS: - retbleed_mitigation = RETBLEED_MITIGATION_IBRS; - break; - case SPECTRE_V2_EIBRS: - case SPECTRE_V2_EIBRS_RETPOLINE: - case SPECTRE_V2_EIBRS_LFENCE: - retbleed_mitigation = RETBLEED_MITIGATION_EIBRS; - break; - default: - if (retbleed_mitigation != RETBLEED_MITIGATION_STUFF) - pr_err(RETBLEED_INTEL_MSG); - } - } - - pr_info("%s\n", retbleed_strings[retbleed_mitigation]); } #undef pr_fmt @@ -1264,6 +1403,8 @@ enum spectre_v2_mitigation_cmd { SPECTRE_V2_CMD_IBRS, }; +static enum spectre_v2_mitigation_cmd spectre_v2_cmd __ro_after_init = SPECTRE_V2_CMD_AUTO; + enum spectre_v2_user_cmd { SPECTRE_V2_USER_CMD_NONE, SPECTRE_V2_USER_CMD_AUTO, @@ -1302,31 +1443,18 @@ static void __init spec_v2_user_print_cond(const char *reason, bool secure) pr_info("spectre_v2_user=%s forced on command line.\n", reason); } -static __ro_after_init enum spectre_v2_mitigation_cmd spectre_v2_cmd; - -static enum spectre_v2_user_cmd __init -spectre_v2_parse_user_cmdline(void) +static enum spectre_v2_user_cmd __init spectre_v2_parse_user_cmdline(void) { - enum spectre_v2_user_cmd mode; char arg[20]; int ret, i; - mode = IS_ENABLED(CONFIG_MITIGATION_SPECTRE_V2) ? - SPECTRE_V2_USER_CMD_AUTO : SPECTRE_V2_USER_CMD_NONE; - - switch (spectre_v2_cmd) { - case SPECTRE_V2_CMD_NONE: + if (cpu_mitigations_off() || !IS_ENABLED(CONFIG_MITIGATION_SPECTRE_V2)) return SPECTRE_V2_USER_CMD_NONE; - case SPECTRE_V2_CMD_FORCE: - return SPECTRE_V2_USER_CMD_FORCE; - default: - break; - } ret = cmdline_find_option(boot_command_line, "spectre_v2_user", arg, sizeof(arg)); if (ret < 0) - return mode; + return SPECTRE_V2_USER_CMD_AUTO; for (i = 0; i < ARRAY_SIZE(v2_user_options); i++) { if (match_option(arg, ret, v2_user_options[i].option)) { @@ -1337,7 +1465,7 @@ spectre_v2_parse_user_cmdline(void) } pr_err("Unknown user space protection option (%s). Switching to default\n", arg); - return mode; + return SPECTRE_V2_USER_CMD_AUTO; } static inline bool spectre_v2_in_ibrs_mode(enum spectre_v2_mitigation mode) @@ -1345,60 +1473,72 @@ static inline bool spectre_v2_in_ibrs_mode(enum spectre_v2_mitigation mode) return spectre_v2_in_eibrs_mode(mode) || mode == SPECTRE_V2_IBRS; } -static void __init -spectre_v2_user_select_mitigation(void) +static void __init spectre_v2_user_select_mitigation(void) { - enum spectre_v2_user_mitigation mode = SPECTRE_V2_USER_NONE; - enum spectre_v2_user_cmd cmd; - if (!boot_cpu_has(X86_FEATURE_IBPB) && !boot_cpu_has(X86_FEATURE_STIBP)) return; - cmd = spectre_v2_parse_user_cmdline(); - switch (cmd) { + switch (spectre_v2_parse_user_cmdline()) { case SPECTRE_V2_USER_CMD_NONE: - goto set_mode; + return; case SPECTRE_V2_USER_CMD_FORCE: - mode = SPECTRE_V2_USER_STRICT; + spectre_v2_user_ibpb = SPECTRE_V2_USER_STRICT; + spectre_v2_user_stibp = SPECTRE_V2_USER_STRICT; break; case SPECTRE_V2_USER_CMD_AUTO: case SPECTRE_V2_USER_CMD_PRCTL: + spectre_v2_user_ibpb = SPECTRE_V2_USER_PRCTL; + spectre_v2_user_stibp = SPECTRE_V2_USER_PRCTL; + break; case SPECTRE_V2_USER_CMD_PRCTL_IBPB: - mode = SPECTRE_V2_USER_PRCTL; + spectre_v2_user_ibpb = SPECTRE_V2_USER_STRICT; + spectre_v2_user_stibp = SPECTRE_V2_USER_PRCTL; break; case SPECTRE_V2_USER_CMD_SECCOMP: + if (IS_ENABLED(CONFIG_SECCOMP)) + spectre_v2_user_ibpb = SPECTRE_V2_USER_SECCOMP; + else + spectre_v2_user_ibpb = SPECTRE_V2_USER_PRCTL; + spectre_v2_user_stibp = spectre_v2_user_ibpb; + break; case SPECTRE_V2_USER_CMD_SECCOMP_IBPB: + spectre_v2_user_ibpb = SPECTRE_V2_USER_STRICT; if (IS_ENABLED(CONFIG_SECCOMP)) - mode = SPECTRE_V2_USER_SECCOMP; + spectre_v2_user_stibp = SPECTRE_V2_USER_SECCOMP; else - mode = SPECTRE_V2_USER_PRCTL; + spectre_v2_user_stibp = SPECTRE_V2_USER_PRCTL; break; } - /* Initialize Indirect Branch Prediction Barrier */ - if (boot_cpu_has(X86_FEATURE_IBPB)) { - static_branch_enable(&switch_vcpu_ibpb); + /* + * At this point, an STIBP mode other than "off" has been set. + * If STIBP support is not being forced, check if STIBP always-on + * is preferred. + */ + if ((spectre_v2_user_stibp == SPECTRE_V2_USER_PRCTL || + spectre_v2_user_stibp == SPECTRE_V2_USER_SECCOMP) && + boot_cpu_has(X86_FEATURE_AMD_STIBP_ALWAYS_ON)) + spectre_v2_user_stibp = SPECTRE_V2_USER_STRICT_PREFERRED; - spectre_v2_user_ibpb = mode; - switch (cmd) { - case SPECTRE_V2_USER_CMD_NONE: - break; - case SPECTRE_V2_USER_CMD_FORCE: - case SPECTRE_V2_USER_CMD_PRCTL_IBPB: - case SPECTRE_V2_USER_CMD_SECCOMP_IBPB: - static_branch_enable(&switch_mm_always_ibpb); - spectre_v2_user_ibpb = SPECTRE_V2_USER_STRICT; - break; - case SPECTRE_V2_USER_CMD_PRCTL: - case SPECTRE_V2_USER_CMD_AUTO: - case SPECTRE_V2_USER_CMD_SECCOMP: - static_branch_enable(&switch_mm_cond_ibpb); - break; - } + if (!boot_cpu_has(X86_FEATURE_IBPB)) + spectre_v2_user_ibpb = SPECTRE_V2_USER_NONE; - pr_info("mitigation: Enabling %s Indirect Branch Prediction Barrier\n", - static_key_enabled(&switch_mm_always_ibpb) ? - "always-on" : "conditional"); + if (!boot_cpu_has(X86_FEATURE_STIBP)) + spectre_v2_user_stibp = SPECTRE_V2_USER_NONE; +} + +static void __init spectre_v2_user_update_mitigation(void) +{ + if (!boot_cpu_has(X86_FEATURE_IBPB) && !boot_cpu_has(X86_FEATURE_STIBP)) + return; + + /* The spectre_v2 cmd line can override spectre_v2_user options */ + if (spectre_v2_cmd == SPECTRE_V2_CMD_NONE) { + spectre_v2_user_ibpb = SPECTRE_V2_USER_NONE; + spectre_v2_user_stibp = SPECTRE_V2_USER_NONE; + } else if (spectre_v2_cmd == SPECTRE_V2_CMD_FORCE) { + spectre_v2_user_ibpb = SPECTRE_V2_USER_STRICT; + spectre_v2_user_stibp = SPECTRE_V2_USER_STRICT; } /* @@ -1416,30 +1556,44 @@ spectre_v2_user_select_mitigation(void) if (!boot_cpu_has(X86_FEATURE_STIBP) || !cpu_smt_possible() || (spectre_v2_in_eibrs_mode(spectre_v2_enabled) && - !boot_cpu_has(X86_FEATURE_AUTOIBRS))) + !boot_cpu_has(X86_FEATURE_AUTOIBRS))) { + spectre_v2_user_stibp = SPECTRE_V2_USER_NONE; return; + } - /* - * At this point, an STIBP mode other than "off" has been set. - * If STIBP support is not being forced, check if STIBP always-on - * is preferred. - */ - if (mode != SPECTRE_V2_USER_STRICT && - boot_cpu_has(X86_FEATURE_AMD_STIBP_ALWAYS_ON)) - mode = SPECTRE_V2_USER_STRICT_PREFERRED; - - if (retbleed_mitigation == RETBLEED_MITIGATION_UNRET || - retbleed_mitigation == RETBLEED_MITIGATION_IBPB) { - if (mode != SPECTRE_V2_USER_STRICT && - mode != SPECTRE_V2_USER_STRICT_PREFERRED) + if (spectre_v2_user_stibp != SPECTRE_V2_USER_NONE && + (retbleed_mitigation == RETBLEED_MITIGATION_UNRET || + retbleed_mitigation == RETBLEED_MITIGATION_IBPB)) { + if (spectre_v2_user_stibp != SPECTRE_V2_USER_STRICT && + spectre_v2_user_stibp != SPECTRE_V2_USER_STRICT_PREFERRED) pr_info("Selecting STIBP always-on mode to complement retbleed mitigation\n"); - mode = SPECTRE_V2_USER_STRICT_PREFERRED; + spectre_v2_user_stibp = SPECTRE_V2_USER_STRICT_PREFERRED; } + pr_info("%s\n", spectre_v2_user_strings[spectre_v2_user_stibp]); +} + +static void __init spectre_v2_user_apply_mitigation(void) +{ + /* Initialize Indirect Branch Prediction Barrier */ + if (spectre_v2_user_ibpb != SPECTRE_V2_USER_NONE) { + static_branch_enable(&switch_vcpu_ibpb); - spectre_v2_user_stibp = mode; + switch (spectre_v2_user_ibpb) { + case SPECTRE_V2_USER_STRICT: + static_branch_enable(&switch_mm_always_ibpb); + break; + case SPECTRE_V2_USER_PRCTL: + case SPECTRE_V2_USER_SECCOMP: + static_branch_enable(&switch_mm_cond_ibpb); + break; + default: + break; + } -set_mode: - pr_info("%s\n", spectre_v2_user_strings[mode]); + pr_info("mitigation: Enabling %s Indirect Branch Prediction Barrier\n", + static_key_enabled(&switch_mm_always_ibpb) ? + "always-on" : "conditional"); + } } static const char * const spectre_v2_strings[] = { @@ -1659,12 +1813,13 @@ static bool __init spec_ctrl_bhi_dis(void) enum bhi_mitigations { BHI_MITIGATION_OFF, + BHI_MITIGATION_AUTO, BHI_MITIGATION_ON, BHI_MITIGATION_VMEXIT_ONLY, }; static enum bhi_mitigations bhi_mitigation __ro_after_init = - IS_ENABLED(CONFIG_MITIGATION_SPECTRE_BHI) ? BHI_MITIGATION_ON : BHI_MITIGATION_OFF; + IS_ENABLED(CONFIG_MITIGATION_SPECTRE_BHI) ? BHI_MITIGATION_AUTO : BHI_MITIGATION_OFF; static int __init spectre_bhi_parse_cmdline(char *str) { @@ -1686,6 +1841,25 @@ early_param("spectre_bhi", spectre_bhi_parse_cmdline); static void __init bhi_select_mitigation(void) { + if (!boot_cpu_has(X86_BUG_BHI) || cpu_mitigations_off()) + bhi_mitigation = BHI_MITIGATION_OFF; + + if (bhi_mitigation == BHI_MITIGATION_AUTO) + bhi_mitigation = BHI_MITIGATION_ON; +} + +static void __init bhi_update_mitigation(void) +{ + if (spectre_v2_cmd == SPECTRE_V2_CMD_NONE) + bhi_mitigation = BHI_MITIGATION_OFF; + + if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2) && + spectre_v2_cmd == SPECTRE_V2_CMD_AUTO) + bhi_mitigation = BHI_MITIGATION_OFF; +} + +static void __init bhi_apply_mitigation(void) +{ if (bhi_mitigation == BHI_MITIGATION_OFF) return; @@ -1717,75 +1891,80 @@ static void __init bhi_select_mitigation(void) static void __init spectre_v2_select_mitigation(void) { - enum spectre_v2_mitigation_cmd cmd = spectre_v2_parse_cmdline(); - enum spectre_v2_mitigation mode = SPECTRE_V2_NONE; + spectre_v2_cmd = spectre_v2_parse_cmdline(); - /* - * If the CPU is not affected and the command line mode is NONE or AUTO - * then nothing to do. - */ if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2) && - (cmd == SPECTRE_V2_CMD_NONE || cmd == SPECTRE_V2_CMD_AUTO)) + (spectre_v2_cmd == SPECTRE_V2_CMD_NONE || spectre_v2_cmd == SPECTRE_V2_CMD_AUTO)) return; - switch (cmd) { + switch (spectre_v2_cmd) { case SPECTRE_V2_CMD_NONE: return; case SPECTRE_V2_CMD_FORCE: case SPECTRE_V2_CMD_AUTO: if (boot_cpu_has(X86_FEATURE_IBRS_ENHANCED)) { - mode = SPECTRE_V2_EIBRS; - break; - } - - if (IS_ENABLED(CONFIG_MITIGATION_IBRS_ENTRY) && - boot_cpu_has_bug(X86_BUG_RETBLEED) && - retbleed_cmd != RETBLEED_CMD_OFF && - retbleed_cmd != RETBLEED_CMD_STUFF && - boot_cpu_has(X86_FEATURE_IBRS) && - boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) { - mode = SPECTRE_V2_IBRS; + spectre_v2_enabled = SPECTRE_V2_EIBRS; break; } - mode = spectre_v2_select_retpoline(); + spectre_v2_enabled = spectre_v2_select_retpoline(); break; case SPECTRE_V2_CMD_RETPOLINE_LFENCE: pr_err(SPECTRE_V2_LFENCE_MSG); - mode = SPECTRE_V2_LFENCE; + spectre_v2_enabled = SPECTRE_V2_LFENCE; break; case SPECTRE_V2_CMD_RETPOLINE_GENERIC: - mode = SPECTRE_V2_RETPOLINE; + spectre_v2_enabled = SPECTRE_V2_RETPOLINE; break; case SPECTRE_V2_CMD_RETPOLINE: - mode = spectre_v2_select_retpoline(); + spectre_v2_enabled = spectre_v2_select_retpoline(); break; case SPECTRE_V2_CMD_IBRS: - mode = SPECTRE_V2_IBRS; + spectre_v2_enabled = SPECTRE_V2_IBRS; break; case SPECTRE_V2_CMD_EIBRS: - mode = SPECTRE_V2_EIBRS; + spectre_v2_enabled = SPECTRE_V2_EIBRS; break; case SPECTRE_V2_CMD_EIBRS_LFENCE: - mode = SPECTRE_V2_EIBRS_LFENCE; + spectre_v2_enabled = SPECTRE_V2_EIBRS_LFENCE; break; case SPECTRE_V2_CMD_EIBRS_RETPOLINE: - mode = SPECTRE_V2_EIBRS_RETPOLINE; + spectre_v2_enabled = SPECTRE_V2_EIBRS_RETPOLINE; break; } +} + +static void __init spectre_v2_update_mitigation(void) +{ + if (spectre_v2_cmd == SPECTRE_V2_CMD_AUTO) { + if (IS_ENABLED(CONFIG_MITIGATION_IBRS_ENTRY) && + boot_cpu_has_bug(X86_BUG_RETBLEED) && + retbleed_mitigation != RETBLEED_MITIGATION_NONE && + retbleed_mitigation != RETBLEED_MITIGATION_STUFF && + boot_cpu_has(X86_FEATURE_IBRS) && + boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) { + spectre_v2_enabled = SPECTRE_V2_IBRS; + } + } - if (mode == SPECTRE_V2_EIBRS && unprivileged_ebpf_enabled()) + if (boot_cpu_has_bug(X86_BUG_SPECTRE_V2) && !cpu_mitigations_off()) + pr_info("%s\n", spectre_v2_strings[spectre_v2_enabled]); +} + +static void __init spectre_v2_apply_mitigation(void) +{ + if (spectre_v2_enabled == SPECTRE_V2_EIBRS && unprivileged_ebpf_enabled()) pr_err(SPECTRE_V2_EIBRS_EBPF_MSG); - if (spectre_v2_in_ibrs_mode(mode)) { + if (spectre_v2_in_ibrs_mode(spectre_v2_enabled)) { if (boot_cpu_has(X86_FEATURE_AUTOIBRS)) { msr_set_bit(MSR_EFER, _EFER_AUTOIBRS); } else { @@ -1794,8 +1973,10 @@ static void __init spectre_v2_select_mitigation(void) } } - switch (mode) { + switch (spectre_v2_enabled) { case SPECTRE_V2_NONE: + return; + case SPECTRE_V2_EIBRS: break; @@ -1821,18 +2002,12 @@ static void __init spectre_v2_select_mitigation(void) * JMPs gets protection against BHI and Intramode-BTI, but RET * prediction from a non-RSB predictor is still a risk. */ - if (mode == SPECTRE_V2_EIBRS_LFENCE || - mode == SPECTRE_V2_EIBRS_RETPOLINE || - mode == SPECTRE_V2_RETPOLINE) + if (spectre_v2_enabled == SPECTRE_V2_EIBRS_LFENCE || + spectre_v2_enabled == SPECTRE_V2_EIBRS_RETPOLINE || + spectre_v2_enabled == SPECTRE_V2_RETPOLINE) spec_ctrl_disable_kernel_rrsba(); - if (boot_cpu_has(X86_BUG_BHI)) - bhi_select_mitigation(); - - spectre_v2_enabled = mode; - pr_info("%s\n", spectre_v2_strings[mode]); - - spectre_v2_select_rsb_mitigation(mode); + spectre_v2_select_rsb_mitigation(spectre_v2_enabled); /* * Retpoline protects the kernel, but doesn't protect firmware. IBRS @@ -1840,28 +2015,26 @@ static void __init spectre_v2_select_mitigation(void) * firmware calls only when IBRS / Enhanced / Automatic IBRS aren't * otherwise enabled. * - * Use "mode" to check Enhanced IBRS instead of boot_cpu_has(), because - * the user might select retpoline on the kernel command line and if - * the CPU supports Enhanced IBRS, kernel might un-intentionally not - * enable IBRS around firmware calls. + * Use "spectre_v2_enabled" to check Enhanced IBRS instead of + * boot_cpu_has(), because the user might select retpoline on the kernel + * command line and if the CPU supports Enhanced IBRS, kernel might + * un-intentionally not enable IBRS around firmware calls. */ if (boot_cpu_has_bug(X86_BUG_RETBLEED) && boot_cpu_has(X86_FEATURE_IBPB) && (boot_cpu_data.x86_vendor == X86_VENDOR_AMD || boot_cpu_data.x86_vendor == X86_VENDOR_HYGON)) { - if (retbleed_cmd != RETBLEED_CMD_IBPB) { + if (retbleed_mitigation != RETBLEED_MITIGATION_IBPB) { setup_force_cpu_cap(X86_FEATURE_USE_IBPB_FW); pr_info("Enabling Speculation Barrier for firmware calls\n"); } - } else if (boot_cpu_has(X86_FEATURE_IBRS) && !spectre_v2_in_ibrs_mode(mode)) { + } else if (boot_cpu_has(X86_FEATURE_IBRS) && + !spectre_v2_in_ibrs_mode(spectre_v2_enabled)) { setup_force_cpu_cap(X86_FEATURE_USE_IBRS_FW); pr_info("Enabling Restricted Speculation for firmware calls\n"); } - - /* Set up IBPB and STIBP depending on the general spectre V2 command */ - spectre_v2_cmd = cmd; } static void update_stibp_msr(void * __unused) @@ -2050,19 +2223,18 @@ static enum ssb_mitigation_cmd __init ssb_parse_cmdline(void) return cmd; } -static enum ssb_mitigation __init __ssb_select_mitigation(void) +static void __init ssb_select_mitigation(void) { - enum ssb_mitigation mode = SPEC_STORE_BYPASS_NONE; enum ssb_mitigation_cmd cmd; if (!boot_cpu_has(X86_FEATURE_SSBD)) - return mode; + goto out; cmd = ssb_parse_cmdline(); if (!boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS) && (cmd == SPEC_STORE_BYPASS_CMD_NONE || cmd == SPEC_STORE_BYPASS_CMD_AUTO)) - return mode; + return; switch (cmd) { case SPEC_STORE_BYPASS_CMD_SECCOMP: @@ -2071,28 +2243,35 @@ static enum ssb_mitigation __init __ssb_select_mitigation(void) * enabled. */ if (IS_ENABLED(CONFIG_SECCOMP)) - mode = SPEC_STORE_BYPASS_SECCOMP; + ssb_mode = SPEC_STORE_BYPASS_SECCOMP; else - mode = SPEC_STORE_BYPASS_PRCTL; + ssb_mode = SPEC_STORE_BYPASS_PRCTL; break; case SPEC_STORE_BYPASS_CMD_ON: - mode = SPEC_STORE_BYPASS_DISABLE; + ssb_mode = SPEC_STORE_BYPASS_DISABLE; break; case SPEC_STORE_BYPASS_CMD_AUTO: case SPEC_STORE_BYPASS_CMD_PRCTL: - mode = SPEC_STORE_BYPASS_PRCTL; + ssb_mode = SPEC_STORE_BYPASS_PRCTL; break; case SPEC_STORE_BYPASS_CMD_NONE: break; } +out: + if (boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS)) + pr_info("%s\n", ssb_strings[ssb_mode]); +} + +static void __init ssb_apply_mitigation(void) +{ /* * We have three CPU feature flags that are in play here: * - X86_BUG_SPEC_STORE_BYPASS - CPU is susceptible. * - X86_FEATURE_SSBD - CPU is able to turn off speculative store bypass * - X86_FEATURE_SPEC_STORE_BYPASS_DISABLE - engage the mitigation */ - if (mode == SPEC_STORE_BYPASS_DISABLE) { + if (ssb_mode == SPEC_STORE_BYPASS_DISABLE) { setup_force_cpu_cap(X86_FEATURE_SPEC_STORE_BYPASS_DISABLE); /* * Intel uses the SPEC CTRL MSR Bit(2) for this, while AMD may @@ -2106,16 +2285,6 @@ static enum ssb_mitigation __init __ssb_select_mitigation(void) update_spec_ctrl(x86_spec_ctrl_base); } } - - return mode; -} - -static void ssb_select_mitigation(void) -{ - ssb_mode = __ssb_select_mitigation(); - - if (boot_cpu_has_bug(X86_BUG_SPEC_STORE_BYPASS)) - pr_info("%s\n", ssb_strings[ssb_mode]); } #undef pr_fmt @@ -2371,7 +2540,7 @@ EXPORT_SYMBOL_GPL(itlb_multihit_kvm_mitigation); /* Default mitigation for L1TF-affected CPUs */ enum l1tf_mitigations l1tf_mitigation __ro_after_init = - IS_ENABLED(CONFIG_MITIGATION_L1TF) ? L1TF_MITIGATION_FLUSH : L1TF_MITIGATION_OFF; + IS_ENABLED(CONFIG_MITIGATION_L1TF) ? L1TF_MITIGATION_AUTO : L1TF_MITIGATION_OFF; #if IS_ENABLED(CONFIG_KVM_INTEL) EXPORT_SYMBOL_GPL(l1tf_mitigation); #endif @@ -2419,22 +2588,33 @@ static void override_cache_bits(struct cpuinfo_x86 *c) static void __init l1tf_select_mitigation(void) { + if (!boot_cpu_has_bug(X86_BUG_L1TF) || cpu_mitigations_off()) { + l1tf_mitigation = L1TF_MITIGATION_OFF; + return; + } + + if (l1tf_mitigation == L1TF_MITIGATION_AUTO) { + if (cpu_mitigations_auto_nosmt()) + l1tf_mitigation = L1TF_MITIGATION_FLUSH_NOSMT; + else + l1tf_mitigation = L1TF_MITIGATION_FLUSH; + } +} + +static void __init l1tf_apply_mitigation(void) +{ u64 half_pa; if (!boot_cpu_has_bug(X86_BUG_L1TF)) return; - if (cpu_mitigations_off()) - l1tf_mitigation = L1TF_MITIGATION_OFF; - else if (cpu_mitigations_auto_nosmt()) - l1tf_mitigation = L1TF_MITIGATION_FLUSH_NOSMT; - override_cache_bits(&boot_cpu_data); switch (l1tf_mitigation) { case L1TF_MITIGATION_OFF: case L1TF_MITIGATION_FLUSH_NOWARN: case L1TF_MITIGATION_FLUSH: + case L1TF_MITIGATION_AUTO: break; case L1TF_MITIGATION_FLUSH_NOSMT: case L1TF_MITIGATION_FULL: @@ -2494,6 +2674,7 @@ early_param("l1tf", l1tf_cmdline); enum srso_mitigation { SRSO_MITIGATION_NONE, + SRSO_MITIGATION_AUTO, SRSO_MITIGATION_UCODE_NEEDED, SRSO_MITIGATION_SAFE_RET_UCODE_NEEDED, SRSO_MITIGATION_MICROCODE, @@ -2503,14 +2684,6 @@ enum srso_mitigation { SRSO_MITIGATION_BP_SPEC_REDUCE, }; -enum srso_mitigation_cmd { - SRSO_CMD_OFF, - SRSO_CMD_MICROCODE, - SRSO_CMD_SAFE_RET, - SRSO_CMD_IBPB, - SRSO_CMD_IBPB_ON_VMEXIT, -}; - static const char * const srso_strings[] = { [SRSO_MITIGATION_NONE] = "Vulnerable", [SRSO_MITIGATION_UCODE_NEEDED] = "Vulnerable: No microcode", @@ -2522,8 +2695,7 @@ static const char * const srso_strings[] = { [SRSO_MITIGATION_BP_SPEC_REDUCE] = "Mitigation: Reduced Speculation" }; -static enum srso_mitigation srso_mitigation __ro_after_init = SRSO_MITIGATION_NONE; -static enum srso_mitigation_cmd srso_cmd __ro_after_init = SRSO_CMD_SAFE_RET; +static enum srso_mitigation srso_mitigation __ro_after_init = SRSO_MITIGATION_AUTO; static int __init srso_parse_cmdline(char *str) { @@ -2531,15 +2703,15 @@ static int __init srso_parse_cmdline(char *str) return -EINVAL; if (!strcmp(str, "off")) - srso_cmd = SRSO_CMD_OFF; + srso_mitigation = SRSO_MITIGATION_NONE; else if (!strcmp(str, "microcode")) - srso_cmd = SRSO_CMD_MICROCODE; + srso_mitigation = SRSO_MITIGATION_MICROCODE; else if (!strcmp(str, "safe-ret")) - srso_cmd = SRSO_CMD_SAFE_RET; + srso_mitigation = SRSO_MITIGATION_SAFE_RET; else if (!strcmp(str, "ibpb")) - srso_cmd = SRSO_CMD_IBPB; + srso_mitigation = SRSO_MITIGATION_IBPB; else if (!strcmp(str, "ibpb-vmexit")) - srso_cmd = SRSO_CMD_IBPB_ON_VMEXIT; + srso_mitigation = SRSO_MITIGATION_IBPB_ON_VMEXIT; else pr_err("Ignoring unknown SRSO option (%s).", str); @@ -2551,132 +2723,83 @@ early_param("spec_rstack_overflow", srso_parse_cmdline); static void __init srso_select_mitigation(void) { - bool has_microcode = boot_cpu_has(X86_FEATURE_IBPB_BRTYPE); + bool has_microcode; - if (!boot_cpu_has_bug(X86_BUG_SRSO) || - cpu_mitigations_off() || - srso_cmd == SRSO_CMD_OFF) { - if (boot_cpu_has(X86_FEATURE_SBPB)) - x86_pred_cmd = PRED_CMD_SBPB; - goto out; - } + if (!boot_cpu_has_bug(X86_BUG_SRSO) || cpu_mitigations_off()) + srso_mitigation = SRSO_MITIGATION_NONE; + + if (srso_mitigation == SRSO_MITIGATION_NONE) + return; + if (srso_mitigation == SRSO_MITIGATION_AUTO) + srso_mitigation = SRSO_MITIGATION_SAFE_RET; + + has_microcode = boot_cpu_has(X86_FEATURE_IBPB_BRTYPE); if (has_microcode) { /* * Zen1/2 with SMT off aren't vulnerable after the right * IBPB microcode has been applied. - * - * Zen1/2 don't have SBPB, no need to try to enable it here. */ if (boot_cpu_data.x86 < 0x19 && !cpu_smt_possible()) { setup_force_cpu_cap(X86_FEATURE_SRSO_NO); - goto out; - } - - if (retbleed_mitigation == RETBLEED_MITIGATION_IBPB) { - srso_mitigation = SRSO_MITIGATION_IBPB; - goto out; + srso_mitigation = SRSO_MITIGATION_NONE; + return; } } else { pr_warn("IBPB-extending microcode not applied!\n"); pr_warn(SRSO_NOTICE); - - /* may be overwritten by SRSO_CMD_SAFE_RET below */ - srso_mitigation = SRSO_MITIGATION_UCODE_NEEDED; } - switch (srso_cmd) { - case SRSO_CMD_MICROCODE: - if (has_microcode) { - srso_mitigation = SRSO_MITIGATION_MICROCODE; - pr_warn(SRSO_NOTICE); - } - break; - - case SRSO_CMD_SAFE_RET: - if (boot_cpu_has(X86_FEATURE_SRSO_USER_KERNEL_NO)) + switch (srso_mitigation) { + case SRSO_MITIGATION_SAFE_RET: + if (boot_cpu_has(X86_FEATURE_SRSO_USER_KERNEL_NO)) { + srso_mitigation = SRSO_MITIGATION_IBPB_ON_VMEXIT; goto ibpb_on_vmexit; + } - if (IS_ENABLED(CONFIG_MITIGATION_SRSO)) { - /* - * Enable the return thunk for generated code - * like ftrace, static_call, etc. - */ - setup_force_cpu_cap(X86_FEATURE_RETHUNK); - setup_force_cpu_cap(X86_FEATURE_UNRET); - - if (boot_cpu_data.x86 == 0x19) { - setup_force_cpu_cap(X86_FEATURE_SRSO_ALIAS); - x86_return_thunk = srso_alias_return_thunk; - } else { - setup_force_cpu_cap(X86_FEATURE_SRSO); - x86_return_thunk = srso_return_thunk; - } - if (has_microcode) - srso_mitigation = SRSO_MITIGATION_SAFE_RET; - else - srso_mitigation = SRSO_MITIGATION_SAFE_RET_UCODE_NEEDED; - } else { + if (!IS_ENABLED(CONFIG_MITIGATION_SRSO)) { pr_err("WARNING: kernel not compiled with MITIGATION_SRSO.\n"); + srso_mitigation = SRSO_MITIGATION_NONE; } - break; - case SRSO_CMD_IBPB: - if (IS_ENABLED(CONFIG_MITIGATION_IBPB_ENTRY)) { - if (has_microcode) { - setup_force_cpu_cap(X86_FEATURE_ENTRY_IBPB); - setup_force_cpu_cap(X86_FEATURE_IBPB_ON_VMEXIT); - srso_mitigation = SRSO_MITIGATION_IBPB; - - /* - * IBPB on entry already obviates the need for - * software-based untraining so clear those in case some - * other mitigation like Retbleed has selected them. - */ - setup_clear_cpu_cap(X86_FEATURE_UNRET); - setup_clear_cpu_cap(X86_FEATURE_RETHUNK); - - /* - * There is no need for RSB filling: write_ibpb() ensures - * all predictions, including the RSB, are invalidated, - * regardless of IBPB implementation. - */ - setup_clear_cpu_cap(X86_FEATURE_RSB_VMEXIT); - } - } else { - pr_err("WARNING: kernel not compiled with MITIGATION_IBPB_ENTRY.\n"); - } + if (!has_microcode) + srso_mitigation = SRSO_MITIGATION_SAFE_RET_UCODE_NEEDED; break; - ibpb_on_vmexit: - case SRSO_CMD_IBPB_ON_VMEXIT: + case SRSO_MITIGATION_IBPB_ON_VMEXIT: if (boot_cpu_has(X86_FEATURE_SRSO_BP_SPEC_REDUCE)) { pr_notice("Reducing speculation to address VM/HV SRSO attack vector.\n"); srso_mitigation = SRSO_MITIGATION_BP_SPEC_REDUCE; break; } - - if (IS_ENABLED(CONFIG_MITIGATION_IBPB_ENTRY)) { - if (has_microcode) { - setup_force_cpu_cap(X86_FEATURE_IBPB_ON_VMEXIT); - srso_mitigation = SRSO_MITIGATION_IBPB_ON_VMEXIT; - - /* - * There is no need for RSB filling: write_ibpb() ensures - * all predictions, including the RSB, are invalidated, - * regardless of IBPB implementation. - */ - setup_clear_cpu_cap(X86_FEATURE_RSB_VMEXIT); - } - } else { + fallthrough; + case SRSO_MITIGATION_IBPB: + if (!IS_ENABLED(CONFIG_MITIGATION_IBPB_ENTRY)) { pr_err("WARNING: kernel not compiled with MITIGATION_IBPB_ENTRY.\n"); + srso_mitigation = SRSO_MITIGATION_NONE; } + + if (!has_microcode) + srso_mitigation = SRSO_MITIGATION_UCODE_NEEDED; break; default: break; } +} -out: +static void __init srso_update_mitigation(void) +{ + /* If retbleed is using IBPB, that works for SRSO as well */ + if (retbleed_mitigation == RETBLEED_MITIGATION_IBPB && + boot_cpu_has(X86_FEATURE_IBPB_BRTYPE)) + srso_mitigation = SRSO_MITIGATION_IBPB; + + if (boot_cpu_has_bug(X86_BUG_SRSO) && !cpu_mitigations_off()) + pr_info("%s\n", srso_strings[srso_mitigation]); +} + +static void __init srso_apply_mitigation(void) +{ /* * Clear the feature flag if this mitigation is not selected as that * feature flag controls the BpSpecReduce MSR bit toggling in KVM. @@ -2684,8 +2807,52 @@ out: if (srso_mitigation != SRSO_MITIGATION_BP_SPEC_REDUCE) setup_clear_cpu_cap(X86_FEATURE_SRSO_BP_SPEC_REDUCE); - if (srso_mitigation != SRSO_MITIGATION_NONE) - pr_info("%s\n", srso_strings[srso_mitigation]); + if (srso_mitigation == SRSO_MITIGATION_NONE) { + if (boot_cpu_has(X86_FEATURE_SBPB)) + x86_pred_cmd = PRED_CMD_SBPB; + return; + } + + switch (srso_mitigation) { + case SRSO_MITIGATION_SAFE_RET: + case SRSO_MITIGATION_SAFE_RET_UCODE_NEEDED: + /* + * Enable the return thunk for generated code + * like ftrace, static_call, etc. + */ + setup_force_cpu_cap(X86_FEATURE_RETHUNK); + setup_force_cpu_cap(X86_FEATURE_UNRET); + + if (boot_cpu_data.x86 == 0x19) { + setup_force_cpu_cap(X86_FEATURE_SRSO_ALIAS); + x86_return_thunk = srso_alias_return_thunk; + } else { + setup_force_cpu_cap(X86_FEATURE_SRSO); + x86_return_thunk = srso_return_thunk; + } + break; + case SRSO_MITIGATION_IBPB: + setup_force_cpu_cap(X86_FEATURE_ENTRY_IBPB); + /* + * IBPB on entry already obviates the need for + * software-based untraining so clear those in case some + * other mitigation like Retbleed has selected them. + */ + setup_clear_cpu_cap(X86_FEATURE_UNRET); + setup_clear_cpu_cap(X86_FEATURE_RETHUNK); + fallthrough; + case SRSO_MITIGATION_IBPB_ON_VMEXIT: + setup_force_cpu_cap(X86_FEATURE_IBPB_ON_VMEXIT); + /* + * There is no need for RSB filling: entry_ibpb() ensures + * all predictions, including the RSB, are invalidated, + * regardless of IBPB implementation. + */ + setup_clear_cpu_cap(X86_FEATURE_RSB_VMEXIT); + break; + default: + break; + } } #undef pr_fmt diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 5c5766467a61..0aba4719ae0a 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -273,6 +273,7 @@ static int vmx_setup_l1d_flush(enum vmx_l1d_flush_state l1tf) case L1TF_MITIGATION_OFF: l1tf = VMENTER_L1D_FLUSH_NEVER; break; + case L1TF_MITIGATION_AUTO: case L1TF_MITIGATION_FLUSH_NOWARN: case L1TF_MITIGATION_FLUSH: case L1TF_MITIGATION_FLUSH_NOSMT: @@ -7358,10 +7359,14 @@ static noinstr void vmx_vcpu_enter_exit(struct kvm_vcpu *vcpu, * mitigation for MDS is done late in VMentry and is still * executed in spite of L1D Flush. This is because an extra VERW * should not matter much after the big hammer L1D Flush. + * + * cpu_buf_vm_clear is used when system is not vulnerable to MDS/TAA, + * and is affected by MMIO Stale Data. In such cases mitigation in only + * needed against an MMIO capable guest. */ if (static_branch_unlikely(&vmx_l1d_should_flush)) vmx_l1d_flush(vcpu); - else if (static_branch_unlikely(&mmio_stale_data_clear) && + else if (static_branch_unlikely(&cpu_buf_vm_clear) && kvm_arch_has_assigned_device(vcpu->kvm)) mds_clear_cpu_buffers(); @@ -7700,6 +7705,7 @@ int vmx_vm_init(struct kvm *kvm) case L1TF_MITIGATION_FLUSH_NOWARN: /* 'I explicitly don't care' is set */ break; + case L1TF_MITIGATION_AUTO: case L1TF_MITIGATION_FLUSH: case L1TF_MITIGATION_FLUSH_NOSMT: case L1TF_MITIGATION_FULL: |