From b190a043c49af4587f5e157053f909192820522a Mon Sep 17 00:00:00 2001 From: Michael Roth Date: Thu, 24 Feb 2022 10:56:18 -0600 Subject: x86/sev: Add SEV-SNP feature detection/setup Initial/preliminary detection of SEV-SNP is done via the Confidential Computing blob. Check for it prior to the normal SEV/SME feature initialization, and add some sanity checks to confirm it agrees with SEV-SNP CPUID/MSR bits. Signed-off-by: Michael Roth Signed-off-by: Brijesh Singh Signed-off-by: Borislav Petkov Link: https://lore.kernel.org/r/20220307213356.2797205-39-brijesh.singh@amd.com --- arch/x86/boot/compressed/sev.c | 27 ---------------- arch/x86/include/asm/sev.h | 2 ++ arch/x86/kernel/sev-shared.c | 27 ++++++++++++++++ arch/x86/kernel/sev.c | 64 ++++++++++++++++++++++++++++++++++++++ arch/x86/mm/mem_encrypt_identity.c | 8 +++++ 5 files changed, 101 insertions(+), 27 deletions(-) diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c index 1e4930ce2c95..82079ce7be06 100644 --- a/arch/x86/boot/compressed/sev.c +++ b/arch/x86/boot/compressed/sev.c @@ -352,33 +352,6 @@ static struct cc_blob_sev_info *find_cc_blob_efi(struct boot_params *bp) EFI_CC_BLOB_GUID); } -struct cc_setup_data { - struct setup_data header; - u32 cc_blob_address; -}; - -/* - * Search for a Confidential Computing blob passed in as a setup_data entry - * via the Linux Boot Protocol. - */ -static struct cc_blob_sev_info *find_cc_blob_setup_data(struct boot_params *bp) -{ - struct cc_setup_data *sd = NULL; - struct setup_data *hdr; - - hdr = (struct setup_data *)bp->hdr.setup_data; - - while (hdr) { - if (hdr->type == SETUP_CC_BLOB) { - sd = (struct cc_setup_data *)hdr; - return (struct cc_blob_sev_info *)(unsigned long)sd->cc_blob_address; - } - hdr = (struct setup_data *)hdr->next; - } - - return NULL; -} - /* * Initial set up of SNP relies on information provided by the * Confidential Computing blob, which can be passed to the boot kernel diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h index 31b3b10323b6..84d3d5121e9c 100644 --- a/arch/x86/include/asm/sev.h +++ b/arch/x86/include/asm/sev.h @@ -153,6 +153,7 @@ void snp_set_memory_shared(unsigned long vaddr, unsigned int npages); void snp_set_memory_private(unsigned long vaddr, unsigned int npages); void snp_set_wakeup_secondary_cpu(void); bool snp_init(struct boot_params *bp); +void snp_abort(void); #else static inline void sev_es_ist_enter(struct pt_regs *regs) { } static inline void sev_es_ist_exit(void) { } @@ -171,6 +172,7 @@ static inline void snp_set_memory_shared(unsigned long vaddr, unsigned int npage static inline void snp_set_memory_private(unsigned long vaddr, unsigned int npages) { } static inline void snp_set_wakeup_secondary_cpu(void) { } static inline bool snp_init(struct boot_params *bp) { return false; } +static inline void snp_abort(void) { } #endif #endif diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c index 0f1375164ff0..a7a1c0fb298e 100644 --- a/arch/x86/kernel/sev-shared.c +++ b/arch/x86/kernel/sev-shared.c @@ -937,3 +937,30 @@ static enum es_result vc_handle_rdtsc(struct ghcb *ghcb, return ES_OK; } + +struct cc_setup_data { + struct setup_data header; + u32 cc_blob_address; +}; + +/* + * Search for a Confidential Computing blob passed in as a setup_data entry + * via the Linux Boot Protocol. + */ +static struct cc_blob_sev_info *find_cc_blob_setup_data(struct boot_params *bp) +{ + struct cc_setup_data *sd = NULL; + struct setup_data *hdr; + + hdr = (struct setup_data *)bp->hdr.setup_data; + + while (hdr) { + if (hdr->type == SETUP_CC_BLOB) { + sd = (struct cc_setup_data *)hdr; + return (struct cc_blob_sev_info *)(unsigned long)sd->cc_blob_address; + } + hdr = (struct setup_data *)hdr->next; + } + + return NULL; +} diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c index 0c2bf39c4a8f..692da7b29127 100644 --- a/arch/x86/kernel/sev.c +++ b/arch/x86/kernel/sev.c @@ -1974,3 +1974,67 @@ fail: while (true) halt(); } + +/* + * Initial set up of SNP relies on information provided by the + * Confidential Computing blob, which can be passed to the kernel + * in the following ways, depending on how it is booted: + * + * - when booted via the boot/decompress kernel: + * - via boot_params + * + * - when booted directly by firmware/bootloader (e.g. CONFIG_PVH): + * - via a setup_data entry, as defined by the Linux Boot Protocol + * + * Scan for the blob in that order. + */ +static __init struct cc_blob_sev_info *find_cc_blob(struct boot_params *bp) +{ + struct cc_blob_sev_info *cc_info; + + /* Boot kernel would have passed the CC blob via boot_params. */ + if (bp->cc_blob_address) { + cc_info = (struct cc_blob_sev_info *)(unsigned long)bp->cc_blob_address; + goto found_cc_info; + } + + /* + * If kernel was booted directly, without the use of the + * boot/decompression kernel, the CC blob may have been passed via + * setup_data instead. + */ + cc_info = find_cc_blob_setup_data(bp); + if (!cc_info) + return NULL; + +found_cc_info: + if (cc_info->magic != CC_BLOB_SEV_HDR_MAGIC) + snp_abort(); + + return cc_info; +} + +bool __init snp_init(struct boot_params *bp) +{ + struct cc_blob_sev_info *cc_info; + + if (!bp) + return false; + + cc_info = find_cc_blob(bp); + if (!cc_info) + return false; + + /* + * The CC blob will be used later to access the secrets page. Cache + * it here like the boot kernel does. + */ + bp->cc_blob_address = (u32)(unsigned long)cc_info; + + return true; +} + +void __init snp_abort(void) +{ + sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SNP_UNSUPPORTED); +} diff --git a/arch/x86/mm/mem_encrypt_identity.c b/arch/x86/mm/mem_encrypt_identity.c index b43bc24d2bb6..f415498d3175 100644 --- a/arch/x86/mm/mem_encrypt_identity.c +++ b/arch/x86/mm/mem_encrypt_identity.c @@ -45,6 +45,7 @@ #include #include #include +#include #include "mm_internal.h" @@ -509,8 +510,11 @@ void __init sme_enable(struct boot_params *bp) bool active_by_default; unsigned long me_mask; char buffer[16]; + bool snp; u64 msr; + snp = snp_init(bp); + /* Check for the SME/SEV support leaf */ eax = 0x80000000; ecx = 0; @@ -542,6 +546,10 @@ void __init sme_enable(struct boot_params *bp) sev_status = __rdmsr(MSR_AMD64_SEV); feature_mask = (sev_status & MSR_AMD64_SEV_ENABLED) ? AMD_SEV_BIT : AMD_SME_BIT; + /* The SEV-SNP CC blob should never be present unless SEV-SNP is enabled. */ + if (snp && !(sev_status & MSR_AMD64_SEV_SNP_ENABLED)) + snp_abort(); + /* Check if memory encryption is enabled */ if (feature_mask == AMD_SME_BIT) { /* -- cgit 1.4.1