From 4b28f0846ef6521b47ee95ea7d77c9d40a7baf29 Mon Sep 17 00:00:00 2001 From: Tycho Andersen Date: Thu, 16 Apr 2026 16:23:24 -0700 Subject: crypto/ccp: export firmware supported vm types In some configurations, the firmware does not support all VM types. The SEV firmware has an entry in the TCB_VERSION structure referred to as the Security Version Number in the SEV-SNP firmware specification and referred to as the "SPL" in SEV firmware release notes. The SEV firmware release notes say: On every SEV firmware release where a security mitigation has been added, the SNP SPL gets increased by 1. This is to let users know that it is important to update to this version. The SEV firmware release that fixed CVE-2025-48514 by disabling SEV-ES support on vulnerable platforms has this SVN increased to reflect the fix. The SVN is platform-specific, as is the structure of TCB_VERSION. Check CURRENT_TCB instead of REPORTED_TCB, since the firmware behaves with the CURRENT_TCB SVN level and will reject SEV-ES VMs accordingly. Parse the SVN, and mask off the SEV_ES supported VM type from the list of supported types if it is above the per-platform threshold for the relevant platforms. Signed-off-by: Tycho Andersen (AMD) Acked-by: Herbert Xu Reviewed-by: Tom Lendacky Tested-by: Tycho Andersen (AMD) Link: https://patch.msgid.link/20260416232329.3408497-3-seanjc@google.com Signed-off-by: Sean Christopherson --- include/linux/psp-sev.h | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) (limited to 'include/linux') diff --git a/include/linux/psp-sev.h b/include/linux/psp-sev.h index d5099a2baca5..ce16bbc0b308 100644 --- a/include/linux/psp-sev.h +++ b/include/linux/psp-sev.h @@ -902,6 +902,42 @@ struct snp_feature_info { /* Feature bits in EBX */ #define SNP_SEV_TIO_SUPPORTED BIT(1) +/** + * struct sev_snp_tcb_version_genoa_milan + * + * @boot_loader: SVN of PSP bootloader + * @tee: SVN of PSP operating system + * @reserved: reserved + * @snp: SVN of SNP firmware + * @microcode: Lowest current patch level of all cores + */ +struct sev_snp_tcb_version_genoa_milan { + u8 boot_loader; + u8 tee; + u8 reserved[4]; + u8 snp; + u8 microcode; +}; + +/** + * struct sev_snp_tcb_version_turin + * + * @fmc: SVN of FMC firmware + * @boot_loader: SVN of PSP bootloader + * @tee: SVN of PSP operating system + * @snp: SVN of SNP firmware + * @reserved: reserved + * @microcode: Lowest current patch level of all cores + */ +struct sev_snp_tcb_version_turin { + u8 fmc; + u8 boot_loader; + u8 tee; + u8 snp; + u8 reserved[3]; + u8 microcode; +}; + #ifdef CONFIG_CRYPTO_DEV_SP_PSP /** @@ -1048,6 +1084,7 @@ void snp_free_firmware_page(void *addr); void sev_platform_shutdown(void); bool sev_is_snp_ciphertext_hiding_supported(void); u64 sev_get_snp_policy_bits(void); +int sev_firmware_supported_vm_types(void); #else /* !CONFIG_CRYPTO_DEV_SP_PSP */ -- cgit v1.2.3 From f13e900599089b10113ceb36013423f0837c6792 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Fri, 22 May 2026 15:46:06 -0700 Subject: KVM: SEV: Pin source page for write when adding CPUID data for SNP guest When populating a guest_memfd instance with the initial CPUID data for an SNP guest, acquire a writable pin on the source page as KVM will write back the "correct" CPUID information if the userspace provided data is rejected by trusted firmware. Because KVM writes to the source page using a kernel mapping, pinning for read could result in KVM clobbering read-only memory. Note, well-behaved VMMs are unlikely to be affected, as CPUID information is almost always dynamically generated by userspace, i.e. it's unlikely for the CPUID information to be backed by a read-only mapping. Fixes: 2a62345b30529 ("KVM: guest_memfd: GUP source pages prior to populating guest memory") Cc: stable@vger.kernel.org Signed-off-by: Ackerley Tng Link: https://patch.msgid.link/20260522-fix-sev-gmem-post-populate-v2-1-3f196bfad5a1@google.com [sean: rewrite shortlog and changelog, tag for stable@] Signed-off-by: Sean Christopherson --- arch/x86/kvm/svm/sev.c | 1 + arch/x86/kvm/vmx/tdx.c | 2 +- include/linux/kvm_host.h | 3 ++- virt/kvm/guest_memfd.c | 6 ++++-- 4 files changed, 8 insertions(+), 4 deletions(-) (limited to 'include/linux') diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 37d4cfa5d980..c73c028d72c1 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -2456,6 +2456,7 @@ static int snp_launch_update(struct kvm *kvm, struct kvm_sev_cmd *argp) sev_populate_args.type = params.type; count = kvm_gmem_populate(kvm, params.gfn_start, src, npages, + params.type == KVM_SEV_SNP_PAGE_TYPE_CPUID, sev_gmem_post_populate, &sev_populate_args); if (count < 0) { argp->error = sev_populate_args.fw_error; diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c index b8c3d3d8bbfe..00dcfcbc47f6 100644 --- a/arch/x86/kvm/vmx/tdx.c +++ b/arch/x86/kvm/vmx/tdx.c @@ -3185,7 +3185,7 @@ static int tdx_vcpu_init_mem_region(struct kvm_vcpu *vcpu, struct kvm_tdx_cmd *c }; gmem_ret = kvm_gmem_populate(kvm, gpa_to_gfn(region.gpa), u64_to_user_ptr(region.source_addr), - 1, tdx_gmem_post_populate, &arg); + 1, false, tdx_gmem_post_populate, &arg); if (gmem_ret < 0) { ret = gmem_ret; break; diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 4c14aee1fb06..2c5ad9a6d5ce 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -2596,7 +2596,8 @@ int kvm_arch_gmem_prepare(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn, int max_ord typedef int (*kvm_gmem_populate_cb)(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn, struct page *page, void *opaque); -long kvm_gmem_populate(struct kvm *kvm, gfn_t gfn, void __user *src, long npages, +long kvm_gmem_populate(struct kvm *kvm, gfn_t start_gfn, void __user *src, + long npages, bool may_writeback_src, kvm_gmem_populate_cb post_populate, void *opaque); #endif diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c index 69c9d6d546b2..07d8db344872 100644 --- a/virt/kvm/guest_memfd.c +++ b/virt/kvm/guest_memfd.c @@ -858,7 +858,8 @@ out_unlock: return ret; } -long kvm_gmem_populate(struct kvm *kvm, gfn_t start_gfn, void __user *src, long npages, +long kvm_gmem_populate(struct kvm *kvm, gfn_t start_gfn, void __user *src, + long npages, bool may_writeback_src, kvm_gmem_populate_cb post_populate, void *opaque) { struct kvm_memory_slot *slot; @@ -892,8 +893,9 @@ long kvm_gmem_populate(struct kvm *kvm, gfn_t start_gfn, void __user *src, long if (src) { unsigned long uaddr = (unsigned long)src + i * PAGE_SIZE; + unsigned int flags = may_writeback_src ? FOLL_WRITE : 0; - ret = get_user_pages_fast(uaddr, 1, 0, &src_page); + ret = get_user_pages_fast(uaddr, 1, flags, &src_page); if (ret < 0) break; if (ret != 1) { -- cgit v1.2.3