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-rw-r--r--Documentation/virt/kvm/api.rst49
-rw-r--r--arch/x86/include/asm/kvm_host.h7
-rw-r--r--arch/x86/include/asm/vmx.h7
-rw-r--r--arch/x86/include/asm/vmxfeatures.h1
-rw-r--r--arch/x86/include/uapi/asm/vmx.h4
-rw-r--r--arch/x86/kvm/vmx/capabilities.h6
-rw-r--r--arch/x86/kvm/vmx/nested.c8
-rw-r--r--arch/x86/kvm/vmx/vmx.c40
-rw-r--r--arch/x86/kvm/x86.c22
-rw-r--r--arch/x86/kvm/x86.h7
-rw-r--r--include/uapi/linux/kvm.h11
11 files changed, 158 insertions, 4 deletions
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index f67e367c4059..30e31a886422 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -6559,6 +6559,26 @@ spec refer, https://github.com/riscv/riscv-sbi-doc.
::
+ /* KVM_EXIT_NOTIFY */
+ struct {
+ #define KVM_NOTIFY_CONTEXT_INVALID (1 << 0)
+ __u32 flags;
+ } notify;
+
+Used on x86 systems. When the VM capability KVM_CAP_X86_NOTIFY_VMEXIT is
+enabled, a VM exit generated if no event window occurs in VM non-root mode
+for a specified amount of time. Once KVM_X86_NOTIFY_VMEXIT_USER is set when
+enabling the cap, it would exit to userspace with the exit reason
+KVM_EXIT_NOTIFY for further handling. The "flags" field contains more
+detailed info.
+
+The valid value for 'flags' is:
+
+ - KVM_NOTIFY_CONTEXT_INVALID -- the VM context is corrupted and not valid
+ in VMCS. It would run into unknown result if resume the target VM.
+
+::
+
/* Fix the size of the union. */
char padding[256];
};
@@ -7523,6 +7543,35 @@ if the value was set to zero or KVM_ENABLE_CAP was not invoked, KVM
uses the return value of KVM_CHECK_EXTENSION(KVM_CAP_MAX_VCPU_ID) as
the maximum APIC ID.
+7.33 KVM_CAP_X86_NOTIFY_VMEXIT
+------------------------------
+
+:Architectures: x86
+:Target: VM
+:Parameters: args[0] is the value of notify window as well as some flags
+:Returns: 0 on success, -EINVAL if args[0] contains invalid flags or notify
+ VM exit is unsupported.
+
+Bits 63:32 of args[0] are used for notify window.
+Bits 31:0 of args[0] are for some flags. Valid bits are::
+
+ #define KVM_X86_NOTIFY_VMEXIT_ENABLED (1 << 0)
+ #define KVM_X86_NOTIFY_VMEXIT_USER (1 << 1)
+
+This capability allows userspace to configure the notify VM exit on/off
+in per-VM scope during VM creation. Notify VM exit is disabled by default.
+When userspace sets KVM_X86_NOTIFY_VMEXIT_ENABLED bit in args[0], VMM will
+enable this feature with the notify window provided, which will generate
+a VM exit if no event window occurs in VM non-root mode for a specified of
+time (notify window).
+
+If KVM_X86_NOTIFY_VMEXIT_USER is set in args[0], upon notify VM exits happen,
+KVM would exit to userspace for handling.
+
+This capability is aimed to mitigate the threat that malicious VMs can
+cause CPU stuck (due to event windows don't open up) and make the CPU
+unavailable to host or other VMs.
+
8. Other capabilities.
======================
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 4e00bca08cfa..6cf5d77d7896 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -65,6 +65,9 @@
#define KVM_BUS_LOCK_DETECTION_VALID_MODE (KVM_BUS_LOCK_DETECTION_OFF | \
KVM_BUS_LOCK_DETECTION_EXIT)
+#define KVM_X86_NOTIFY_VMEXIT_VALID_BITS (KVM_X86_NOTIFY_VMEXIT_ENABLED | \
+ KVM_X86_NOTIFY_VMEXIT_USER)
+
/* x86-specific vcpu->requests bit members */
#define KVM_REQ_MIGRATE_TIMER KVM_ARCH_REQ(0)
#define KVM_REQ_REPORT_TPR_ACCESS KVM_ARCH_REQ(1)
@@ -1178,6 +1181,9 @@ struct kvm_arch {
bool bus_lock_detection_enabled;
bool enable_pmu;
+
+ u32 notify_window;
+ u32 notify_vmexit_flags;
/*
* If exit_on_emulation_error is set, and the in-kernel instruction
* emulator fails to emulate an instruction, allow userspace
@@ -1325,6 +1331,7 @@ struct kvm_vcpu_stat {
u64 directed_yield_attempted;
u64 directed_yield_successful;
u64 guest_mode;
+ u64 notify_window_exits;
};
struct x86_instruction_info;
diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index 89d2172787c5..c371ef695fcc 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -75,6 +75,7 @@
#define SECONDARY_EXEC_TSC_SCALING VMCS_CONTROL_BIT(TSC_SCALING)
#define SECONDARY_EXEC_ENABLE_USR_WAIT_PAUSE VMCS_CONTROL_BIT(USR_WAIT_PAUSE)
#define SECONDARY_EXEC_BUS_LOCK_DETECTION VMCS_CONTROL_BIT(BUS_LOCK_DETECTION)
+#define SECONDARY_EXEC_NOTIFY_VM_EXITING VMCS_CONTROL_BIT(NOTIFY_VM_EXITING)
/*
* Definitions of Tertiary Processor-Based VM-Execution Controls.
@@ -280,6 +281,7 @@ enum vmcs_field {
SECONDARY_VM_EXEC_CONTROL = 0x0000401e,
PLE_GAP = 0x00004020,
PLE_WINDOW = 0x00004022,
+ NOTIFY_WINDOW = 0x00004024,
VM_INSTRUCTION_ERROR = 0x00004400,
VM_EXIT_REASON = 0x00004402,
VM_EXIT_INTR_INFO = 0x00004404,
@@ -565,6 +567,11 @@ enum vm_entry_failure_code {
#define EPT_VIOLATION_GVA_TRANSLATED (1 << EPT_VIOLATION_GVA_TRANSLATED_BIT)
/*
+ * Exit Qualifications for NOTIFY VM EXIT
+ */
+#define NOTIFY_VM_CONTEXT_INVALID BIT(0)
+
+/*
* VM-instruction error numbers
*/
enum vm_instruction_error_number {
diff --git a/arch/x86/include/asm/vmxfeatures.h b/arch/x86/include/asm/vmxfeatures.h
index 589608c157bf..c6a7eed03914 100644
--- a/arch/x86/include/asm/vmxfeatures.h
+++ b/arch/x86/include/asm/vmxfeatures.h
@@ -85,6 +85,7 @@
#define VMX_FEATURE_USR_WAIT_PAUSE ( 2*32+ 26) /* Enable TPAUSE, UMONITOR, UMWAIT in guest */
#define VMX_FEATURE_ENCLV_EXITING ( 2*32+ 28) /* "" VM-Exit on ENCLV (leaf dependent) */
#define VMX_FEATURE_BUS_LOCK_DETECTION ( 2*32+ 30) /* "" VM-Exit when bus lock caused */
+#define VMX_FEATURE_NOTIFY_VM_EXITING ( 2*32+ 31) /* VM-Exit when no event windows after notify window */
/* Tertiary Processor-Based VM-Execution Controls, word 3 */
#define VMX_FEATURE_IPI_VIRT ( 3*32+ 4) /* Enable IPI virtualization */
diff --git a/arch/x86/include/uapi/asm/vmx.h b/arch/x86/include/uapi/asm/vmx.h
index 946d761adbd3..a5faf6d88f1b 100644
--- a/arch/x86/include/uapi/asm/vmx.h
+++ b/arch/x86/include/uapi/asm/vmx.h
@@ -91,6 +91,7 @@
#define EXIT_REASON_UMWAIT 67
#define EXIT_REASON_TPAUSE 68
#define EXIT_REASON_BUS_LOCK 74
+#define EXIT_REASON_NOTIFY 75
#define VMX_EXIT_REASONS \
{ EXIT_REASON_EXCEPTION_NMI, "EXCEPTION_NMI" }, \
@@ -153,7 +154,8 @@
{ EXIT_REASON_XRSTORS, "XRSTORS" }, \
{ EXIT_REASON_UMWAIT, "UMWAIT" }, \
{ EXIT_REASON_TPAUSE, "TPAUSE" }, \
- { EXIT_REASON_BUS_LOCK, "BUS_LOCK" }
+ { EXIT_REASON_BUS_LOCK, "BUS_LOCK" }, \
+ { EXIT_REASON_NOTIFY, "NOTIFY" }
#define VMX_EXIT_REASON_FLAGS \
{ VMX_EXIT_REASONS_FAILED_VMENTRY, "FAILED_VMENTRY" }
diff --git a/arch/x86/kvm/vmx/capabilities.h b/arch/x86/kvm/vmx/capabilities.h
index f14c4bef97e0..2d3f13b18714 100644
--- a/arch/x86/kvm/vmx/capabilities.h
+++ b/arch/x86/kvm/vmx/capabilities.h
@@ -436,4 +436,10 @@ static inline u64 vmx_supported_debugctl(void)
return debugctl;
}
+static inline bool cpu_has_notify_vmexit(void)
+{
+ return vmcs_config.cpu_based_2nd_exec_ctrl &
+ SECONDARY_EXEC_NOTIFY_VM_EXITING;
+}
+
#endif /* __KVM_X86_VMX_CAPS_H */
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 5c5f4e3762f5..7d8cd0ebcc75 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -2133,6 +2133,8 @@ static u64 nested_vmx_calc_efer(struct vcpu_vmx *vmx, struct vmcs12 *vmcs12)
static void prepare_vmcs02_constant_state(struct vcpu_vmx *vmx)
{
+ struct kvm *kvm = vmx->vcpu.kvm;
+
/*
* If vmcs02 hasn't been initialized, set the constant vmcs02 state
* according to L0's settings (vmcs12 is irrelevant here). Host
@@ -2175,6 +2177,9 @@ static void prepare_vmcs02_constant_state(struct vcpu_vmx *vmx)
if (cpu_has_vmx_encls_vmexit())
vmcs_write64(ENCLS_EXITING_BITMAP, INVALID_GPA);
+ if (kvm_notify_vmexit_enabled(kvm))
+ vmcs_write32(NOTIFY_WINDOW, kvm->arch.notify_window);
+
/*
* Set the MSR load/store lists to match L0's settings. Only the
* addresses are constant (for vmcs02), the counts can change based
@@ -6112,6 +6117,9 @@ static bool nested_vmx_l1_wants_exit(struct kvm_vcpu *vcpu,
SECONDARY_EXEC_ENABLE_USR_WAIT_PAUSE);
case EXIT_REASON_ENCLS:
return nested_vmx_exit_handled_encls(vcpu, vmcs12);
+ case EXIT_REASON_NOTIFY:
+ /* Notify VM exit is not exposed to L1 */
+ return false;
default:
return true;
}
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 6d631941ac1a..2e00890d752a 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2499,7 +2499,8 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf,
SECONDARY_EXEC_PT_USE_GPA |
SECONDARY_EXEC_PT_CONCEAL_VMX |
SECONDARY_EXEC_ENABLE_VMFUNC |
- SECONDARY_EXEC_BUS_LOCK_DETECTION;
+ SECONDARY_EXEC_BUS_LOCK_DETECTION |
+ SECONDARY_EXEC_NOTIFY_VM_EXITING;
if (cpu_has_sgx())
opt2 |= SECONDARY_EXEC_ENCLS_EXITING;
if (adjust_vmx_controls(min2, opt2,
@@ -4417,6 +4418,9 @@ static u32 vmx_secondary_exec_control(struct vcpu_vmx *vmx)
if (!vcpu->kvm->arch.bus_lock_detection_enabled)
exec_control &= ~SECONDARY_EXEC_BUS_LOCK_DETECTION;
+ if (!kvm_notify_vmexit_enabled(vcpu->kvm))
+ exec_control &= ~SECONDARY_EXEC_NOTIFY_VM_EXITING;
+
return exec_control;
}
@@ -4498,6 +4502,9 @@ static void init_vmcs(struct vcpu_vmx *vmx)
vmx->ple_window_dirty = true;
}
+ if (kvm_notify_vmexit_enabled(kvm))
+ vmcs_write32(NOTIFY_WINDOW, kvm->arch.notify_window);
+
vmcs_write32(PAGE_FAULT_ERROR_CODE_MASK, 0);
vmcs_write32(PAGE_FAULT_ERROR_CODE_MATCH, 0);
vmcs_write32(CR3_TARGET_COUNT, 0); /* 22.2.1 */
@@ -5784,6 +5791,32 @@ static int handle_bus_lock_vmexit(struct kvm_vcpu *vcpu)
return 1;
}
+static int handle_notify(struct kvm_vcpu *vcpu)
+{
+ unsigned long exit_qual = vmx_get_exit_qual(vcpu);
+ bool context_invalid = exit_qual & NOTIFY_VM_CONTEXT_INVALID;
+
+ ++vcpu->stat.notify_window_exits;
+
+ /*
+ * Notify VM exit happened while executing iret from NMI,
+ * "blocked by NMI" bit has to be set before next VM entry.
+ */
+ if (enable_vnmi && (exit_qual & INTR_INFO_UNBLOCK_NMI))
+ vmcs_set_bits(GUEST_INTERRUPTIBILITY_INFO,
+ GUEST_INTR_STATE_NMI);
+
+ if (vcpu->kvm->arch.notify_vmexit_flags & KVM_X86_NOTIFY_VMEXIT_USER ||
+ context_invalid) {
+ vcpu->run->exit_reason = KVM_EXIT_NOTIFY;
+ vcpu->run->notify.flags = context_invalid ?
+ KVM_NOTIFY_CONTEXT_INVALID : 0;
+ return 0;
+ }
+
+ return 1;
+}
+
/*
* The exit handlers return 1 if the exit was handled fully and guest execution
* may resume. Otherwise they set the kvm_run parameter to indicate what needs
@@ -5841,6 +5874,7 @@ static int (*kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = {
[EXIT_REASON_PREEMPTION_TIMER] = handle_preemption_timer,
[EXIT_REASON_ENCLS] = handle_encls,
[EXIT_REASON_BUS_LOCK] = handle_bus_lock_vmexit,
+ [EXIT_REASON_NOTIFY] = handle_notify,
};
static const int kvm_vmx_max_exit_handlers =
@@ -6214,7 +6248,8 @@ static int __vmx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t exit_fastpath)
exit_reason.basic != EXIT_REASON_EPT_VIOLATION &&
exit_reason.basic != EXIT_REASON_PML_FULL &&
exit_reason.basic != EXIT_REASON_APIC_ACCESS &&
- exit_reason.basic != EXIT_REASON_TASK_SWITCH)) {
+ exit_reason.basic != EXIT_REASON_TASK_SWITCH &&
+ exit_reason.basic != EXIT_REASON_NOTIFY)) {
int ndata = 3;
vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
@@ -8137,6 +8172,7 @@ static __init int hardware_setup(void)
kvm_caps.max_tsc_scaling_ratio = KVM_VMX_TSC_MULTIPLIER_MAX;
kvm_caps.tsc_scaling_ratio_frac_bits = 48;
kvm_caps.has_bus_lock_exit = cpu_has_vmx_bus_lock_detection();
+ kvm_caps.has_notify_vmexit = cpu_has_notify_vmexit();
set_bit(0, vmx_vpid_bitmap); /* 0 is reserved for host */
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 53e5f2ad2422..a8014233fd57 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -284,7 +284,8 @@ const struct _kvm_stats_desc kvm_vcpu_stats_desc[] = {
STATS_DESC_COUNTER(VCPU, nested_run),
STATS_DESC_COUNTER(VCPU, directed_yield_attempted),
STATS_DESC_COUNTER(VCPU, directed_yield_successful),
- STATS_DESC_ICOUNTER(VCPU, guest_mode)
+ STATS_DESC_ICOUNTER(VCPU, guest_mode),
+ STATS_DESC_COUNTER(VCPU, notify_window_exits),
};
const struct kvm_stats_header kvm_vcpu_stats_header = {
@@ -4402,6 +4403,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
case KVM_CAP_DISABLE_QUIRKS2:
r = KVM_X86_VALID_QUIRKS;
break;
+ case KVM_CAP_X86_NOTIFY_VMEXIT:
+ r = kvm_caps.has_notify_vmexit;
+ break;
default:
break;
}
@@ -6125,6 +6129,22 @@ split_irqchip_unlock:
}
mutex_unlock(&kvm->lock);
break;
+ case KVM_CAP_X86_NOTIFY_VMEXIT:
+ r = -EINVAL;
+ if ((u32)cap->args[0] & ~KVM_X86_NOTIFY_VMEXIT_VALID_BITS)
+ break;
+ if (!kvm_caps.has_notify_vmexit)
+ break;
+ if (!((u32)cap->args[0] & KVM_X86_NOTIFY_VMEXIT_ENABLED))
+ break;
+ mutex_lock(&kvm->lock);
+ if (!kvm->created_vcpus) {
+ kvm->arch.notify_window = cap->args[0] >> 32;
+ kvm->arch.notify_vmexit_flags = (u32)cap->args[0];
+ r = 0;
+ }
+ mutex_unlock(&kvm->lock);
+ break;
default:
r = -EINVAL;
break;
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index 359d0454ad28..501b884b8cc4 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -21,6 +21,8 @@ struct kvm_caps {
u64 default_tsc_scaling_ratio;
/* bus lock detection supported? */
bool has_bus_lock_exit;
+ /* notify VM exit supported? */
+ bool has_notify_vmexit;
u64 supported_mce_cap;
u64 supported_xcr0;
@@ -364,6 +366,11 @@ static inline bool kvm_cstate_in_guest(struct kvm *kvm)
return kvm->arch.cstate_in_guest;
}
+static inline bool kvm_notify_vmexit_enabled(struct kvm *kvm)
+{
+ return kvm->arch.notify_vmexit_flags & KVM_X86_NOTIFY_VMEXIT_ENABLED;
+}
+
enum kvm_intr_type {
/* Values are arbitrary, but must be non-zero. */
KVM_HANDLING_IRQ = 1,
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index ca799319acfd..7569b4ec199c 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -270,6 +270,7 @@ struct kvm_xen_exit {
#define KVM_EXIT_X86_BUS_LOCK 33
#define KVM_EXIT_XEN 34
#define KVM_EXIT_RISCV_SBI 35
+#define KVM_EXIT_NOTIFY 36
/* For KVM_EXIT_INTERNAL_ERROR */
/* Emulate instruction failed. */
@@ -496,6 +497,11 @@ struct kvm_run {
unsigned long args[6];
unsigned long ret[2];
} riscv_sbi;
+ /* KVM_EXIT_NOTIFY */
+ struct {
+#define KVM_NOTIFY_CONTEXT_INVALID (1 << 0)
+ __u32 flags;
+ } notify;
/* Fix the size of the union. */
char padding[256];
};
@@ -1159,6 +1165,7 @@ struct kvm_ppc_resize_hpt {
#define KVM_CAP_ARM_SYSTEM_SUSPEND 216
#define KVM_CAP_S390_PROTECTED_DUMP 217
#define KVM_CAP_X86_TRIPLE_FAULT_EVENT 218
+#define KVM_CAP_X86_NOTIFY_VMEXIT 219
#ifdef KVM_CAP_IRQ_ROUTING
@@ -2174,4 +2181,8 @@ struct kvm_stats_desc {
/* Available with KVM_CAP_S390_PROTECTED_DUMP */
#define KVM_S390_PV_CPU_COMMAND _IOWR(KVMIO, 0xd0, struct kvm_pv_cmd)
+/* Available with KVM_CAP_X86_NOTIFY_VMEXIT */
+#define KVM_X86_NOTIFY_VMEXIT_ENABLED (1ULL << 0)
+#define KVM_X86_NOTIFY_VMEXIT_USER (1ULL << 1)
+
#endif /* __LINUX_KVM_H */
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.