KVM: SEV: Add initial SEV-SNP support

SEV-SNP builds upon existing SEV and SEV-ES functionality while adding
new hardware-based security protection. SEV-SNP adds strong memory
encryption and integrity protection to help prevent malicious
hypervisor-based attacks such as data replay, memory re-mapping, and
more, to create an isolated execution environment.

Define a new KVM_X86_SNP_VM type which makes use of these capabilities
and extend the KVM_SEV_INIT2 ioctl to support it. Also add a basic
helper to check whether SNP is enabled and set PFERR_PRIVATE_ACCESS for
private #NPFs so they are handled appropriately by KVM MMU.

Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Co-developed-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20240501085210.2213060-5-michael.roth@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
index 728c98175b9cb8fd5a229dfdf0ac32f294a06b52..544a43c1cf1123e163a550d0371be6a20035300e 100644 (file)
--- a/arch/x86/include/asm/svm.h
+++ b/arch/x86/include/asm/svm.h
@@ -285,7 +285,8 @@ static_assert((X2AVIC_MAX_PHYSICAL_ID & AVIC_PHYSICAL_MAX_INDEX_MASK) == X2AVIC_
 
 #define AVIC_HPA_MASK  ~((0xFFFULL << 52) | 0xFFF)
 
-#define SVM_SEV_FEAT_DEBUG_SWAP                        BIT(5)
+#define SVM_SEV_FEAT_SNP_ACTIVE                                BIT(0)
+#define SVM_SEV_FEAT_DEBUG_SWAP                                BIT(5)
 
 struct vmcb_seg {
        u16 selector;

diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
index 9fae1b73b529caf53c5c7dd1823fd7a3f320637c..d2ae5fcc02759813a3a2f9981c3afd437b92f24a 100644 (file)
--- a/arch/x86/include/uapi/asm/kvm.h
+++ b/arch/x86/include/uapi/asm/kvm.h
@@ -874,5 +874,6 @@ struct kvm_hyperv_eventfd {
 #define KVM_X86_SW_PROTECTED_VM        1
 #define KVM_X86_SEV_VM         2
 #define KVM_X86_SEV_ES_VM      3
+#define KVM_X86_SNP_VM         4
 
 #endif /* _ASM_X86_KVM_H */

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 0623cfaa7bb0ee9f9ca3ec142e99feb41254533b..b3345d45b989ad08803864ce768eadef97ae24c4 100644 (file)
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -47,6 +47,9 @@ module_param_named(sev, sev_enabled, bool, 0444);
 static bool sev_es_enabled = true;
 module_param_named(sev_es, sev_es_enabled, bool, 0444);
 
+/* enable/disable SEV-SNP support */
+static bool sev_snp_enabled;
+
 /* enable/disable SEV-ES DebugSwap support */
 static bool sev_es_debug_swap_enabled = true;
 module_param_named(debug_swap, sev_es_debug_swap_enabled, bool, 0444);
@@ -288,6 +291,9 @@ static int __sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp,
        if (sev->es_active && !sev->ghcb_version)
                sev->ghcb_version = GHCB_VERSION_DEFAULT;
 
+       if (vm_type == KVM_X86_SNP_VM)
+               sev->vmsa_features |= SVM_SEV_FEAT_SNP_ACTIVE;
+
        ret = sev_asid_new(sev);
        if (ret)
                goto e_no_asid;
@@ -348,7 +354,8 @@ static int sev_guest_init2(struct kvm *kvm, struct kvm_sev_cmd *argp)
                return -EINVAL;
 
        if (kvm->arch.vm_type != KVM_X86_SEV_VM &&
-           kvm->arch.vm_type != KVM_X86_SEV_ES_VM)
+           kvm->arch.vm_type != KVM_X86_SEV_ES_VM &&
+           kvm->arch.vm_type != KVM_X86_SNP_VM)
                return -EINVAL;
 
        if (copy_from_user(&data, u64_to_user_ptr(argp->data), sizeof(data)))
@@ -2328,11 +2335,16 @@ void __init sev_set_cpu_caps(void)
                kvm_cpu_cap_set(X86_FEATURE_SEV_ES);
                kvm_caps.supported_vm_types |= BIT(KVM_X86_SEV_ES_VM);
        }
+       if (sev_snp_enabled) {
+               kvm_cpu_cap_set(X86_FEATURE_SEV_SNP);
+               kvm_caps.supported_vm_types |= BIT(KVM_X86_SNP_VM);
+       }
 }
 
 void __init sev_hardware_setup(void)
 {
        unsigned int eax, ebx, ecx, edx, sev_asid_count, sev_es_asid_count;
+       bool sev_snp_supported = false;
        bool sev_es_supported = false;
        bool sev_supported = false;
 
@@ -2413,6 +2425,7 @@ void __init sev_hardware_setup(void)
        sev_es_asid_count = min_sev_asid - 1;
        WARN_ON_ONCE(misc_cg_set_capacity(MISC_CG_RES_SEV_ES, sev_es_asid_count));
        sev_es_supported = true;
+       sev_snp_supported = sev_snp_enabled && cc_platform_has(CC_ATTR_HOST_SEV_SNP);
 
 out:
        if (boot_cpu_has(X86_FEATURE_SEV))
@@ -2425,9 +2438,15 @@ out:
                pr_info("SEV-ES %s (ASIDs %u - %u)\n",
                        sev_es_supported ? "enabled" : "disabled",
                        min_sev_asid > 1 ? 1 : 0, min_sev_asid - 1);
+       if (boot_cpu_has(X86_FEATURE_SEV_SNP))
+               pr_info("SEV-SNP %s (ASIDs %u - %u)\n",
+                       sev_snp_supported ? "enabled" : "disabled",
+                       min_sev_asid > 1 ? 1 : 0, min_sev_asid - 1);
 
        sev_enabled = sev_supported;
        sev_es_enabled = sev_es_supported;
+       sev_snp_enabled = sev_snp_supported;
+
        if (!sev_es_enabled || !cpu_feature_enabled(X86_FEATURE_DEBUG_SWAP) ||
            !cpu_feature_enabled(X86_FEATURE_NO_NESTED_DATA_BP))
                sev_es_debug_swap_enabled = false;

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index c8dc25886c16581c2e89e94b685fa6c95ad4fc7a..66d5e2e46a66c0e67b3d78b52dcacb4e2ebb4048 100644 (file)
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -2057,6 +2057,9 @@ static int npf_interception(struct kvm_vcpu *vcpu)
        if (WARN_ON_ONCE(error_code & PFERR_SYNTHETIC_MASK))
                error_code &= ~PFERR_SYNTHETIC_MASK;
 
+       if (sev_snp_guest(vcpu->kvm) && (error_code & PFERR_GUEST_ENC_MASK))
+               error_code |= PFERR_PRIVATE_ACCESS;
+
        trace_kvm_page_fault(vcpu, fault_address, error_code);
        return kvm_mmu_page_fault(vcpu, fault_address, error_code,
                        static_cpu_has(X86_FEATURE_DECODEASSISTS) ?
@@ -4902,8 +4905,11 @@ static int svm_vm_init(struct kvm *kvm)
 
        if (type != KVM_X86_DEFAULT_VM &&
            type != KVM_X86_SW_PROTECTED_VM) {
-               kvm->arch.has_protected_state = (type == KVM_X86_SEV_ES_VM);
+               kvm->arch.has_protected_state =
+                       (type == KVM_X86_SEV_ES_VM || type == KVM_X86_SNP_VM);
                to_kvm_sev_info(kvm)->need_init = true;
+
+               kvm->arch.has_private_mem = (type == KVM_X86_SNP_VM);
        }
 
        if (!pause_filter_count || !pause_filter_thresh)

diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index be57213cd295935f055bf46d3856393944108061..583e035d38f80d1339fd340029d2397defdf894a 100644 (file)
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -349,6 +349,18 @@ static __always_inline bool sev_es_guest(struct kvm *kvm)
 #endif
 }
 
+static __always_inline bool sev_snp_guest(struct kvm *kvm)
+{
+#ifdef CONFIG_KVM_AMD_SEV
+       struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
+
+       return (sev->vmsa_features & SVM_SEV_FEAT_SNP_ACTIVE) &&
+              !WARN_ON_ONCE(!sev_es_guest(kvm));
+#else
+       return false;
+#endif
+}
+
 static inline void vmcb_mark_all_dirty(struct vmcb *vmcb)
 {
        vmcb->control.clean = 0;