diff options
Diffstat (limited to 'arch/x86/coco/tdx/tdx.c')
| -rw-r--r-- | arch/x86/coco/tdx/tdx.c | 459 |
1 files changed, 289 insertions, 170 deletions
diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c index 928dcf7a20d9..c1cb90369915 100644 --- a/arch/x86/coco/tdx/tdx.c +++ b/arch/x86/coco/tdx/tdx.c @@ -5,21 +5,16 @@ #define pr_fmt(fmt) "tdx: " fmt #include <linux/cpufeature.h> +#include <linux/export.h> +#include <linux/io.h> #include <asm/coco.h> #include <asm/tdx.h> #include <asm/vmx.h> +#include <asm/ia32.h> #include <asm/insn.h> #include <asm/insn-eval.h> #include <asm/pgtable.h> -/* TDX module Call Leaf IDs */ -#define TDX_GET_INFO 1 -#define TDX_GET_VEINFO 3 -#define TDX_ACCEPT_PAGE 6 - -/* TDX hypercall Leaf IDs */ -#define TDVMCALL_MAP_GPA 0x10001 - /* MMIO direction */ #define EPT_READ 0 #define EPT_WRITE 1 @@ -34,46 +29,27 @@ #define VE_GET_PORT_NUM(e) ((e) >> 16) #define VE_IS_IO_STRING(e) ((e) & BIT(4)) -/* - * Wrapper for standard use of __tdx_hypercall with no output aside from - * return code. - */ -static inline u64 _tdx_hypercall(u64 fn, u64 r12, u64 r13, u64 r14, u64 r15) -{ - struct tdx_hypercall_args args = { - .r10 = TDX_HYPERCALL_STANDARD, - .r11 = fn, - .r12 = r12, - .r13 = r13, - .r14 = r14, - .r15 = r15, - }; +#define ATTR_DEBUG BIT(0) +#define ATTR_SEPT_VE_DISABLE BIT(28) - return __tdx_hypercall(&args, 0); -} +/* TDX Module call error codes */ +#define TDCALL_RETURN_CODE(a) ((a) >> 32) +#define TDCALL_INVALID_OPERAND 0xc0000100 + +#define TDREPORT_SUBTYPE_0 0 /* Called from __tdx_hypercall() for unrecoverable failure */ -void __tdx_hypercall_failed(void) +noinstr void __noreturn __tdx_hypercall_failed(void) { + instrumentation_begin(); panic("TDVMCALL failed. TDX module bug?"); } -/* - * The TDG.VP.VMCALL-Instruction-execution sub-functions are defined - * independently from but are currently matched 1:1 with VMX EXIT_REASONs. - * Reusing the KVM EXIT_REASON macros makes it easier to connect the host and - * guest sides of these calls. - */ -static u64 hcall_func(u64 exit_reason) -{ - return exit_reason; -} - #ifdef CONFIG_KVM_GUEST long tdx_kvm_hypercall(unsigned int nr, unsigned long p1, unsigned long p2, unsigned long p3, unsigned long p4) { - struct tdx_hypercall_args args = { + struct tdx_module_args args = { .r10 = nr, .r11 = p1, .r12 = p2, @@ -81,7 +57,7 @@ long tdx_kvm_hypercall(unsigned int nr, unsigned long p1, unsigned long p2, .r14 = p4, }; - return __tdx_hypercall(&args, 0); + return __tdx_hypercall(&args); } EXPORT_SYMBOL_GPL(tdx_kvm_hypercall); #endif @@ -91,17 +67,107 @@ EXPORT_SYMBOL_GPL(tdx_kvm_hypercall); * should only be used for calls that have no legitimate reason to fail * or where the kernel can not survive the call failing. */ -static inline void tdx_module_call(u64 fn, u64 rcx, u64 rdx, u64 r8, u64 r9, - struct tdx_module_output *out) +static inline void tdcall(u64 fn, struct tdx_module_args *args) { - if (__tdx_module_call(fn, rcx, rdx, r8, r9, out)) + if (__tdcall_ret(fn, args)) panic("TDCALL %lld failed (Buggy TDX module!)\n", fn); } -static u64 get_cc_mask(void) +/** + * tdx_mcall_get_report0() - Wrapper to get TDREPORT0 (a.k.a. TDREPORT + * subtype 0) using TDG.MR.REPORT TDCALL. + * @reportdata: Address of the input buffer which contains user-defined + * REPORTDATA to be included into TDREPORT. + * @tdreport: Address of the output buffer to store TDREPORT. + * + * Refer to section titled "TDG.MR.REPORT leaf" in the TDX Module + * v1.0 specification for more information on TDG.MR.REPORT TDCALL. + * It is used in the TDX guest driver module to get the TDREPORT0. + * + * Return 0 on success, -EINVAL for invalid operands, or -EIO on + * other TDCALL failures. + */ +int tdx_mcall_get_report0(u8 *reportdata, u8 *tdreport) +{ + struct tdx_module_args args = { + .rcx = virt_to_phys(tdreport), + .rdx = virt_to_phys(reportdata), + .r8 = TDREPORT_SUBTYPE_0, + }; + u64 ret; + + ret = __tdcall(TDG_MR_REPORT, &args); + if (ret) { + if (TDCALL_RETURN_CODE(ret) == TDCALL_INVALID_OPERAND) + return -EINVAL; + return -EIO; + } + + return 0; +} +EXPORT_SYMBOL_GPL(tdx_mcall_get_report0); + +/** + * tdx_hcall_get_quote() - Wrapper to request TD Quote using GetQuote + * hypercall. + * @buf: Address of the directly mapped shared kernel buffer which + * contains TDREPORT. The same buffer will be used by VMM to + * store the generated TD Quote output. + * @size: size of the tdquote buffer (4KB-aligned). + * + * Refer to section titled "TDG.VP.VMCALL<GetQuote>" in the TDX GHCI + * v1.0 specification for more information on GetQuote hypercall. + * It is used in the TDX guest driver module to get the TD Quote. + * + * Return 0 on success or error code on failure. + */ +u64 tdx_hcall_get_quote(u8 *buf, size_t size) +{ + /* Since buf is a shared memory, set the shared (decrypted) bits */ + return _tdx_hypercall(TDVMCALL_GET_QUOTE, cc_mkdec(virt_to_phys(buf)), size, 0, 0); +} +EXPORT_SYMBOL_GPL(tdx_hcall_get_quote); + +static void __noreturn tdx_panic(const char *msg) +{ + struct tdx_module_args args = { + .r10 = TDX_HYPERCALL_STANDARD, + .r11 = TDVMCALL_REPORT_FATAL_ERROR, + .r12 = 0, /* Error code: 0 is Panic */ + }; + union { + /* Define register order according to the GHCI */ + struct { u64 r14, r15, rbx, rdi, rsi, r8, r9, rdx; }; + + char str[64]; + } message; + + /* VMM assumes '\0' in byte 65, if the message took all 64 bytes */ + strtomem_pad(message.str, msg, '\0'); + + args.r8 = message.r8; + args.r9 = message.r9; + args.r14 = message.r14; + args.r15 = message.r15; + args.rdi = message.rdi; + args.rsi = message.rsi; + args.rbx = message.rbx; + args.rdx = message.rdx; + + /* + * This hypercall should never return and it is not safe + * to keep the guest running. Call it forever if it + * happens to return. + */ + while (1) + __tdx_hypercall(&args); +} + +static void tdx_parse_tdinfo(u64 *cc_mask) { - struct tdx_module_output out; + struct tdx_module_args args = {}; unsigned int gpa_width; + u64 td_attr; /* * TDINFO TDX module call is used to get the TD execution environment @@ -109,19 +175,34 @@ static u64 get_cc_mask(void) * information, etc. More details about the ABI can be found in TDX * Guest-Host-Communication Interface (GHCI), section 2.4.2 TDCALL * [TDG.VP.INFO]. + */ + tdcall(TDG_VP_INFO, &args); + + /* + * The highest bit of a guest physical address is the "sharing" bit. + * Set it for shared pages and clear it for private pages. * * The GPA width that comes out of this call is critical. TDX guests * can not meaningfully run without it. */ - tdx_module_call(TDX_GET_INFO, 0, 0, 0, 0, &out); - - gpa_width = out.rcx & GENMASK(5, 0); + gpa_width = args.rcx & GENMASK(5, 0); + *cc_mask = BIT_ULL(gpa_width - 1); /* - * The highest bit of a guest physical address is the "sharing" bit. - * Set it for shared pages and clear it for private pages. + * The kernel can not handle #VE's when accessing normal kernel + * memory. Ensure that no #VE will be delivered for accesses to + * TD-private memory. Only VMM-shared memory (MMIO) will #VE. */ - return BIT_ULL(gpa_width - 1); + td_attr = args.rdx; + if (!(td_attr & ATTR_SEPT_VE_DISABLE)) { + const char *msg = "TD misconfiguration: SEPT_VE_DISABLE attribute must be set."; + + /* Relax SEPT_VE_DISABLE check for debug TD. */ + if (td_attr & ATTR_DEBUG) + pr_warn("%s\n", msg); + else + tdx_panic(msg); + } } /* @@ -169,9 +250,9 @@ static int ve_instr_len(struct ve_info *ve) } } -static u64 __cpuidle __halt(const bool irq_disabled, const bool do_sti) +static u64 __cpuidle __halt(const bool irq_disabled) { - struct tdx_hypercall_args args = { + struct tdx_module_args args = { .r10 = TDX_HYPERCALL_STANDARD, .r11 = hcall_func(EXIT_REASON_HLT), .r12 = irq_disabled, @@ -189,20 +270,14 @@ static u64 __cpuidle __halt(const bool irq_disabled, const bool do_sti) * can keep the vCPU in virtual HLT, even if an IRQ is * pending, without hanging/breaking the guest. */ - return __tdx_hypercall(&args, do_sti ? TDX_HCALL_ISSUE_STI : 0); + return __tdx_hypercall(&args); } static int handle_halt(struct ve_info *ve) { - /* - * Since non safe halt is mainly used in CPU offlining - * and the guest will always stay in the halt state, don't - * call the STI instruction (set do_sti as false). - */ const bool irq_disabled = irqs_disabled(); - const bool do_sti = false; - if (__halt(irq_disabled, do_sti)) + if (__halt(irq_disabled)) return -EIO; return ve_instr_len(ve); @@ -210,24 +285,18 @@ static int handle_halt(struct ve_info *ve) void __cpuidle tdx_safe_halt(void) { - /* - * For do_sti=true case, __tdx_hypercall() function enables - * interrupts using the STI instruction before the TDCALL. So - * set irq_disabled as false. - */ const bool irq_disabled = false; - const bool do_sti = true; /* * Use WARN_ONCE() to report the failure. */ - if (__halt(irq_disabled, do_sti)) + if (__halt(irq_disabled)) WARN_ONCE(1, "HLT instruction emulation failed\n"); } static int read_msr(struct pt_regs *regs, struct ve_info *ve) { - struct tdx_hypercall_args args = { + struct tdx_module_args args = { .r10 = TDX_HYPERCALL_STANDARD, .r11 = hcall_func(EXIT_REASON_MSR_READ), .r12 = regs->cx, @@ -238,7 +307,7 @@ static int read_msr(struct pt_regs *regs, struct ve_info *ve) * can be found in TDX Guest-Host-Communication Interface * (GHCI), section titled "TDG.VP.VMCALL<Instruction.RDMSR>". */ - if (__tdx_hypercall(&args, TDX_HCALL_HAS_OUTPUT)) + if (__tdx_hypercall(&args)) return -EIO; regs->ax = lower_32_bits(args.r11); @@ -248,7 +317,7 @@ static int read_msr(struct pt_regs *regs, struct ve_info *ve) static int write_msr(struct pt_regs *regs, struct ve_info *ve) { - struct tdx_hypercall_args args = { + struct tdx_module_args args = { .r10 = TDX_HYPERCALL_STANDARD, .r11 = hcall_func(EXIT_REASON_MSR_WRITE), .r12 = regs->cx, @@ -260,7 +329,7 @@ static int write_msr(struct pt_regs *regs, struct ve_info *ve) * can be found in TDX Guest-Host-Communication Interface * (GHCI) section titled "TDG.VP.VMCALL<Instruction.WRMSR>". */ - if (__tdx_hypercall(&args, 0)) + if (__tdx_hypercall(&args)) return -EIO; return ve_instr_len(ve); @@ -268,7 +337,7 @@ static int write_msr(struct pt_regs *regs, struct ve_info *ve) static int handle_cpuid(struct pt_regs *regs, struct ve_info *ve) { - struct tdx_hypercall_args args = { + struct tdx_module_args args = { .r10 = TDX_HYPERCALL_STANDARD, .r11 = hcall_func(EXIT_REASON_CPUID), .r12 = regs->ax, @@ -292,7 +361,7 @@ static int handle_cpuid(struct pt_regs *regs, struct ve_info *ve) * ABI can be found in TDX Guest-Host-Communication Interface * (GHCI), section titled "VP.VMCALL<Instruction.CPUID>". */ - if (__tdx_hypercall(&args, TDX_HCALL_HAS_OUTPUT)) + if (__tdx_hypercall(&args)) return -EIO; /* @@ -310,7 +379,7 @@ static int handle_cpuid(struct pt_regs *regs, struct ve_info *ve) static bool mmio_read(int size, unsigned long addr, unsigned long *val) { - struct tdx_hypercall_args args = { + struct tdx_module_args args = { .r10 = TDX_HYPERCALL_STANDARD, .r11 = hcall_func(EXIT_REASON_EPT_VIOLATION), .r12 = size, @@ -319,8 +388,9 @@ static bool mmio_read(int size, unsigned long addr, unsigned long *val) .r15 = *val, }; - if (__tdx_hypercall(&args, TDX_HCALL_HAS_OUTPUT)) + if (__tdx_hypercall(&args)) return false; + *val = args.r11; return true; } @@ -335,8 +405,8 @@ static int handle_mmio(struct pt_regs *regs, struct ve_info *ve) { unsigned long *reg, val, vaddr; char buffer[MAX_INSN_SIZE]; + enum insn_mmio_type mmio; struct insn insn = {}; - enum mmio_type mmio; int size, extend_size; u8 extend_val = 0; @@ -351,10 +421,10 @@ static int handle_mmio(struct pt_regs *regs, struct ve_info *ve) return -EINVAL; mmio = insn_decode_mmio(&insn, &size); - if (WARN_ON_ONCE(mmio == MMIO_DECODE_FAILED)) + if (WARN_ON_ONCE(mmio == INSN_MMIO_DECODE_FAILED)) return -EINVAL; - if (mmio != MMIO_WRITE_IMM && mmio != MMIO_MOVS) { + if (mmio != INSN_MMIO_WRITE_IMM && mmio != INSN_MMIO_MOVS) { reg = insn_get_modrm_reg_ptr(&insn, regs); if (!reg) return -EINVAL; @@ -375,23 +445,23 @@ static int handle_mmio(struct pt_regs *regs, struct ve_info *ve) /* Handle writes first */ switch (mmio) { - case MMIO_WRITE: + case INSN_MMIO_WRITE: memcpy(&val, reg, size); if (!mmio_write(size, ve->gpa, val)) return -EIO; return insn.length; - case MMIO_WRITE_IMM: + case INSN_MMIO_WRITE_IMM: val = insn.immediate.value; if (!mmio_write(size, ve->gpa, val)) return -EIO; return insn.length; - case MMIO_READ: - case MMIO_READ_ZERO_EXTEND: - case MMIO_READ_SIGN_EXTEND: + case INSN_MMIO_READ: + case INSN_MMIO_READ_ZERO_EXTEND: + case INSN_MMIO_READ_SIGN_EXTEND: /* Reads are handled below */ break; - case MMIO_MOVS: - case MMIO_DECODE_FAILED: + case INSN_MMIO_MOVS: + case INSN_MMIO_DECODE_FAILED: /* * MMIO was accessed with an instruction that could not be * decoded or handled properly. It was likely not using io.h @@ -408,15 +478,15 @@ static int handle_mmio(struct pt_regs *regs, struct ve_info *ve) return -EIO; switch (mmio) { - case MMIO_READ: + case INSN_MMIO_READ: /* Zero-extend for 32-bit operation */ extend_size = size == 4 ? sizeof(*reg) : 0; break; - case MMIO_READ_ZERO_EXTEND: + case INSN_MMIO_READ_ZERO_EXTEND: /* Zero extend based on operand size */ extend_size = insn.opnd_bytes; break; - case MMIO_READ_SIGN_EXTEND: + case INSN_MMIO_READ_SIGN_EXTEND: /* Sign extend based on operand size */ extend_size = insn.opnd_bytes; if (size == 1 && val & BIT(7)) @@ -438,7 +508,7 @@ static int handle_mmio(struct pt_regs *regs, struct ve_info *ve) static bool handle_in(struct pt_regs *regs, int size, int port) { - struct tdx_hypercall_args args = { + struct tdx_module_args args = { .r10 = TDX_HYPERCALL_STANDARD, .r11 = hcall_func(EXIT_REASON_IO_INSTRUCTION), .r12 = size, @@ -453,7 +523,7 @@ static bool handle_in(struct pt_regs *regs, int size, int port) * in TDX Guest-Host-Communication Interface (GHCI) section titled * "TDG.VP.VMCALL<Instruction.IO>". */ - success = !__tdx_hypercall(&args, TDX_HCALL_HAS_OUTPUT); + success = !__tdx_hypercall(&args); /* Update part of the register affected by the emulated instruction */ regs->ax &= ~mask; @@ -532,7 +602,7 @@ __init bool tdx_early_handle_ve(struct pt_regs *regs) void tdx_get_ve_info(struct ve_info *ve) { - struct tdx_module_output out; + struct tdx_module_args args = {}; /* * Called during #VE handling to retrieve the #VE info from the @@ -549,15 +619,15 @@ void tdx_get_ve_info(struct ve_info *ve) * Note, the TDX module treats virtual NMIs as inhibited if the #VE * valid flag is set. It means that NMI=>#VE will not result in a #DF. */ - tdx_module_call(TDX_GET_VEINFO, 0, 0, 0, 0, &out); + tdcall(TDG_VP_VEINFO_GET, &args); /* Transfer the output parameters */ - ve->exit_reason = out.rcx; - ve->exit_qual = out.rdx; - ve->gla = out.r8; - ve->gpa = out.r9; - ve->instr_len = lower_32_bits(out.r10); - ve->instr_info = upper_32_bits(out.r10); + ve->exit_reason = args.rcx; + ve->exit_qual = args.rdx; + ve->gla = args.r8; + ve->gpa = args.r9; + ve->instr_len = lower_32_bits(args.r10); + ve->instr_info = upper_32_bits(args.r10); } /* @@ -577,6 +647,11 @@ static int virt_exception_user(struct pt_regs *regs, struct ve_info *ve) } } +static inline bool is_private_gpa(u64 gpa) +{ + return gpa == cc_mkenc(gpa); +} + /* * Handle the kernel #VE. * @@ -595,6 +670,8 @@ static int virt_exception_kernel(struct pt_regs *regs, struct ve_info *ve) case EXIT_REASON_CPUID: return handle_cpuid(regs, ve); case EXIT_REASON_EPT_VIOLATION: + if (is_private_gpa(ve->gpa)) + panic("Unexpected EPT-violation on private memory."); return handle_mmio(regs, ve); case EXIT_REASON_IO_INSTRUCTION: return handle_io(regs, ve); @@ -650,45 +727,55 @@ static bool tdx_cache_flush_required(void) return true; } -static bool try_accept_one(phys_addr_t *start, unsigned long len, - enum pg_level pg_level) +/* + * Notify the VMM about page mapping conversion. More info about ABI + * can be found in TDX Guest-Host-Communication Interface (GHCI), + * section "TDG.VP.VMCALL<MapGPA>". + */ +static bool tdx_map_gpa(phys_addr_t start, phys_addr_t end, bool enc) { - unsigned long accept_size = page_level_size(pg_level); - u64 tdcall_rcx; - u8 page_size; + /* Retrying the hypercall a second time should succeed; use 3 just in case */ + const int max_retries_per_page = 3; + int retry_count = 0; - if (!IS_ALIGNED(*start, accept_size)) - return false; + if (!enc) { + /* Set the shared (decrypted) bits: */ + start |= cc_mkdec(0); + end |= cc_mkdec(0); + } - if (len < accept_size) - return false; + while (retry_count < max_retries_per_page) { + struct tdx_module_args args = { + .r10 = TDX_HYPERCALL_STANDARD, + .r11 = TDVMCALL_MAP_GPA, + .r12 = start, + .r13 = end - start }; - /* - * Pass the page physical address to the TDX module to accept the - * pending, private page. - * - * Bits 2:0 of RCX encode page size: 0 - 4K, 1 - 2M, 2 - 1G. - */ - switch (pg_level) { - case PG_LEVEL_4K: - page_size = 0; - break; - case PG_LEVEL_2M: - page_size = 1; - break; - case PG_LEVEL_1G: - page_size = 2; - break; - default: - return false; - } + u64 map_fail_paddr; + u64 ret = __tdx_hypercall(&args); - tdcall_rcx = *start | page_size; - if (__tdx_module_call(TDX_ACCEPT_PAGE, tdcall_rcx, 0, 0, 0, NULL)) - return false; + if (ret != TDVMCALL_STATUS_RETRY) + return !ret; + /* + * The guest must retry the operation for the pages in the + * region starting at the GPA specified in R11. R11 comes + * from the untrusted VMM. Sanity check it. + */ + map_fail_paddr = args.r11; + if (map_fail_paddr < start || map_fail_paddr >= end) + return false; - *start += accept_size; - return true; + /* "Consume" a retry without forward progress */ + if (map_fail_paddr == start) { + retry_count++; + continue; + } + + start = map_fail_paddr; + retry_count = 0; + } + + return false; } /* @@ -701,52 +788,46 @@ static bool tdx_enc_status_changed(unsigned long vaddr, int numpages, bool enc) phys_addr_t start = __pa(vaddr); phys_addr_t end = __pa(vaddr + numpages * PAGE_SIZE); - if (!enc) { - /* Set the shared (decrypted) bits: */ - start |= cc_mkdec(0); - end |= cc_mkdec(0); - } - - /* - * Notify the VMM about page mapping conversion. More info about ABI - * can be found in TDX Guest-Host-Communication Interface (GHCI), - * section "TDG.VP.VMCALL<MapGPA>" - */ - if (_tdx_hypercall(TDVMCALL_MAP_GPA, start, end - start, 0, 0)) + if (!tdx_map_gpa(start, end, enc)) return false; - /* private->shared conversion requires only MapGPA call */ - if (!enc) - return true; + /* shared->private conversion requires memory to be accepted before use */ + if (enc) + return tdx_accept_memory(start, end); + + return true; +} +static bool tdx_enc_status_change_prepare(unsigned long vaddr, int numpages, + bool enc) +{ /* - * For shared->private conversion, accept the page using - * TDX_ACCEPT_PAGE TDX module call. + * Only handle shared->private conversion here. + * See the comment in tdx_early_init(). */ - while (start < end) { - unsigned long len = end - start; - - /* - * Try larger accepts first. It gives chance to VMM to keep - * 1G/2M SEPT entries where possible and speeds up process by - * cutting number of hypercalls (if successful). - */ - - if (try_accept_one(&start, len, PG_LEVEL_1G)) - continue; - - if (try_accept_one(&start, len, PG_LEVEL_2M)) - continue; - - if (!try_accept_one(&start, len, PG_LEVEL_4K)) - return false; - } + if (enc) + return tdx_enc_status_changed(vaddr, numpages, enc); + return true; +} +static bool tdx_enc_status_change_finish(unsigned long vaddr, int numpages, + bool enc) +{ + /* + * Only handle private->shared conversion here. + * See the comment in tdx_early_init(). + */ + if (!enc) + return tdx_enc_status_changed(vaddr, numpages, enc); return true; } void __init tdx_early_init(void) { + struct tdx_module_args args = { + .rdx = TDCS_NOTIFY_ENABLES, + .r9 = -1ULL, + }; u64 cc_mask; u32 eax, sig[3]; @@ -757,10 +838,16 @@ void __init tdx_early_init(void) setup_force_cpu_cap(X86_FEATURE_TDX_GUEST); - cc_set_vendor(CC_VENDOR_INTEL); - cc_mask = get_cc_mask(); + /* TSC is the only reliable clock in TDX guest */ + setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE); + + cc_vendor = CC_VENDOR_INTEL; + tdx_parse_tdinfo(&cc_mask); cc_set_mask(cc_mask); + /* Kernel does not use NOTIFY_ENABLES and does not need random #VEs */ + tdcall(TDG_VM_WR, &args); + /* * All bits above GPA width are reserved and kernel treats shared bit * as flag, not as part of physical address. @@ -769,9 +856,41 @@ void __init tdx_early_init(void) */ physical_mask &= cc_mask - 1; - x86_platform.guest.enc_cache_flush_required = tdx_cache_flush_required; - x86_platform.guest.enc_tlb_flush_required = tdx_tlb_flush_required; - x86_platform.guest.enc_status_change_finish = tdx_enc_status_changed; + /* + * The kernel mapping should match the TDX metadata for the page. + * load_unaligned_zeropad() can touch memory *adjacent* to that which is + * owned by the caller and can catch even _momentary_ mismatches. Bad + * things happen on mismatch: + * + * - Private mapping => Shared Page == Guest shutdown + * - Shared mapping => Private Page == Recoverable #VE + * + * guest.enc_status_change_prepare() converts the page from + * shared=>private before the mapping becomes private. + * + * guest.enc_status_change_finish() converts the page from + * private=>shared after the mapping becomes private. + * + * In both cases there is a temporary shared mapping to a private page, + * which can result in a #VE. But, there is never a private mapping to + * a shared page. + */ + x86_platform.guest.enc_status_change_prepare = tdx_enc_status_change_prepare; + x86_platform.guest.enc_status_change_finish = tdx_enc_status_change_finish; + + x86_platform.guest.enc_cache_flush_required = tdx_cache_flush_required; + x86_platform.guest.enc_tlb_flush_required = tdx_tlb_flush_required; + + /* + * TDX intercepts the RDMSR to read the X2APIC ID in the parallel + * bringup low level code. That raises #VE which cannot be handled + * there. + * + * Intel-TDX has a secure RDMSR hypercall, but that needs to be + * implemented separately in the low level startup ASM code. + * Until that is in place, disable parallel bringup for TDX. + */ + x86_cpuinit.parallel_bringup = false; pr_info("Guest detected\n"); } |