The following commit has been merged into the x86/sev branch of tip: Commit-ID: b6e0f6666f74f0794530e3557f5b0a4ce37bd556 Gitweb: https://git.kernel.org/tip/b6e0f6666f74f0794530e3557f5b0a4ce37bd556 Author: Brijesh Singh <brijesh.singh@xxxxxxx> AuthorDate: Thu, 25 Jan 2024 22:11:01 -06:00 Committer: Borislav Petkov (AMD) <bp@xxxxxxxxx> CommitterDate: Mon, 29 Jan 2024 17:13:16 +01:00 x86/cpufeatures: Add SEV-SNP CPU feature Add CPU feature detection for Secure Encrypted Virtualization with Secure Nested Paging. This feature adds a strong memory integrity protection to help prevent malicious hypervisor-based attacks like data replay, memory re-mapping, and more. Since enabling the SNP CPU feature imposes a number of additional requirements on host initialization and handling legacy firmware APIs for SEV/SEV-ES guests, only introduce the CPU feature bit so that the relevant handling can be added, but leave it disabled via a disabled-features mask. Once all the necessary changes needed to maintain legacy SEV/SEV-ES support are introduced in subsequent patches, the SNP feature bit will be unmasked/enabled. Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx> Signed-off-by: Jarkko Sakkinen <jarkko@xxxxxxxxxxx> Signed-off-by: Ashish Kalra <Ashish.Kalra@xxxxxxx> Signed-off-by: Michael Roth <michael.roth@xxxxxxx> Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx> Link: https://lore.kernel.org/r/20240126041126.1927228-2-michael.roth@xxxxxxx --- arch/x86/include/asm/cpufeatures.h | 1 + arch/x86/include/asm/disabled-features.h | 4 +++- arch/x86/kernel/cpu/amd.c | 5 +++-- tools/arch/x86/include/asm/cpufeatures.h | 1 + 4 files changed, 8 insertions(+), 3 deletions(-) diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h index fdf723b..0fa7026 100644 --- a/arch/x86/include/asm/cpufeatures.h +++ b/arch/x86/include/asm/cpufeatures.h @@ -440,6 +440,7 @@ #define X86_FEATURE_SEV (19*32+ 1) /* AMD Secure Encrypted Virtualization */ #define X86_FEATURE_VM_PAGE_FLUSH (19*32+ 2) /* "" VM Page Flush MSR is supported */ #define X86_FEATURE_SEV_ES (19*32+ 3) /* AMD Secure Encrypted Virtualization - Encrypted State */ +#define X86_FEATURE_SEV_SNP (19*32+ 4) /* AMD Secure Encrypted Virtualization - Secure Nested Paging */ #define X86_FEATURE_V_TSC_AUX (19*32+ 9) /* "" Virtual TSC_AUX */ #define X86_FEATURE_SME_COHERENT (19*32+10) /* "" AMD hardware-enforced cache coherency */ #define X86_FEATURE_DEBUG_SWAP (19*32+14) /* AMD SEV-ES full debug state swap support */ diff --git a/arch/x86/include/asm/disabled-features.h b/arch/x86/include/asm/disabled-features.h index 702d93f..fc13bf7 100644 --- a/arch/x86/include/asm/disabled-features.h +++ b/arch/x86/include/asm/disabled-features.h @@ -117,6 +117,8 @@ #define DISABLE_IBT (1 << (X86_FEATURE_IBT & 31)) #endif +#define DISABLE_SEV_SNP (1 << (X86_FEATURE_SEV_SNP & 31)) + /* * Make sure to add features to the correct mask */ @@ -141,7 +143,7 @@ DISABLE_ENQCMD) #define DISABLED_MASK17 0 #define DISABLED_MASK18 (DISABLE_IBT) -#define DISABLED_MASK19 0 +#define DISABLED_MASK19 (DISABLE_SEV_SNP) #define DISABLED_MASK20 0 #define DISABLED_MASK_CHECK BUILD_BUG_ON_ZERO(NCAPINTS != 21) diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index f3abca3..4baba69 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -605,8 +605,8 @@ static void early_detect_mem_encrypt(struct cpuinfo_x86 *c) * SME feature (set in scattered.c). * If the kernel has not enabled SME via any means then * don't advertise the SME feature. - * For SEV: If BIOS has not enabled SEV then don't advertise the - * SEV and SEV_ES feature (set in scattered.c). + * For SEV: If BIOS has not enabled SEV then don't advertise SEV and + * any additional functionality based on it. * * In all cases, since support for SME and SEV requires long mode, * don't advertise the feature under CONFIG_X86_32. @@ -641,6 +641,7 @@ clear_all: clear_sev: setup_clear_cpu_cap(X86_FEATURE_SEV); setup_clear_cpu_cap(X86_FEATURE_SEV_ES); + setup_clear_cpu_cap(X86_FEATURE_SEV_SNP); } } diff --git a/tools/arch/x86/include/asm/cpufeatures.h b/tools/arch/x86/include/asm/cpufeatures.h index f4542d2..e58bd69 100644 --- a/tools/arch/x86/include/asm/cpufeatures.h +++ b/tools/arch/x86/include/asm/cpufeatures.h @@ -437,6 +437,7 @@ #define X86_FEATURE_SEV (19*32+ 1) /* AMD Secure Encrypted Virtualization */ #define X86_FEATURE_VM_PAGE_FLUSH (19*32+ 2) /* "" VM Page Flush MSR is supported */ #define X86_FEATURE_SEV_ES (19*32+ 3) /* AMD Secure Encrypted Virtualization - Encrypted State */ +#define X86_FEATURE_SEV_SNP (19*32+ 4) /* AMD Secure Encrypted Virtualization - Secure Nested Paging */ #define X86_FEATURE_V_TSC_AUX (19*32+ 9) /* "" Virtual TSC_AUX */ #define X86_FEATURE_SME_COHERENT (19*32+10) /* "" AMD hardware-enforced cache coherency */ #define X86_FEATURE_DEBUG_SWAP (19*32+14) /* AMD SEV-ES full debug state swap support */
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