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KVM: SEV: Add initial SEV-SNP support

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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>
This commit is contained in:
Brijesh Singh 2024-05-01 03:51:54 -05:00 committed by Paolo Bonzini
parent a8e3198333
commit 1dfe571c12
5 changed files with 42 additions and 3 deletions
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3
arch/x86/include/asm/svm.h
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@ -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;

1
arch/x86/include/uapi/asm/kvm.h
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@ -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 */

21
arch/x86/kvm/svm/sev.c
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@ -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;

8
arch/x86/kvm/svm/svm.c
View File

@ -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)

12
arch/x86/kvm/svm/svm.h
View File

@ -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;