AMD EPYC 5th generation processors have introduced a feature that allows
the hypervisor to control the SEV_FEATURES that are set for, or by, a
guest [1]. ALLOWED_SEV_FEATURES can be used by the hypervisor to enforce
that SEV-ES and SEV-SNP guests cannot enable features that the
hypervisor does not want to be enabled.
Always enable ALLOWED_SEV_FEATURES. A VMRUN will fail if any
non-reserved bits are 1 in SEV_FEATURES but are 0 in
ALLOWED_SEV_FEATURES.
Some SEV_FEATURES - currently PmcVirtualization and SecureAvic
(see Appendix B, Table B-4) - require an opt-in via ALLOWED_SEV_FEATURES,
i.e. are off-by-default, whereas all other features are effectively
on-by-default, but still honor ALLOWED_SEV_FEATURES.
[1] Section 15.36.20 "Allowed SEV Features", AMD64 Architecture
Programmer's Manual, Pub. 24593 Rev. 3.42 - March 2024:
https://bugzilla.kernel.org/attachment.cgi?id=306250
Co-developed-by: Kishon Vijay Abraham I <kvijayab@xxxxxxx>
Signed-off-by: Kishon Vijay Abraham I <kvijayab@xxxxxxx>
Reviewed-by: Pankaj Gupta <pankaj.gupta@xxxxxxx>
Signed-off-by: Kim Phillips <kim.phillips@xxxxxxx>
---
arch/x86/include/asm/svm.h | 7 ++++++-
arch/x86/kvm/svm/sev.c | 5 +++++
arch/x86/kvm/svm/svm.c | 2 ++
3 files changed, 13 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
index 9b7fa99ae951..b382fd251e5b 100644
--- a/arch/x86/include/asm/svm.h
+++ b/arch/x86/include/asm/svm.h
@@ -159,7 +159,10 @@ struct __attribute__ ((__packed__)) vmcb_control_area {
u64 avic_physical_id; /* Offset 0xf8 */
u8 reserved_7[8];
u64 vmsa_pa; /* Used for an SEV-ES guest */
- u8 reserved_8[720];
+ u8 reserved_8[40];
+ u64 allowed_sev_features; /* Offset 0x138 */
+ u64 guest_sev_features; /* Offset 0x140 */
+ u8 reserved_9[664];
/*
* Offset 0x3e0, 32 bytes reserved
* for use by hypervisor/software.
@@ -291,6 +294,8 @@ static_assert((X2AVIC_MAX_PHYSICAL_ID & AVIC_PHYSICAL_MAX_INDEX_MASK) == X2AVIC_
#define SVM_SEV_FEAT_ALTERNATE_INJECTION BIT(4)
#define SVM_SEV_FEAT_DEBUG_SWAP BIT(5)
+#define VMCB_ALLOWED_SEV_FEATURES_VALID BIT_ULL(63)
+
struct vmcb_seg {
u16 selector;
u16 attrib;
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 0bc708ee2788..f9ec139901ef 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -4449,6 +4449,7 @@ void sev_vcpu_after_set_cpuid(struct vcpu_svm *svm)
static void sev_es_init_vmcb(struct vcpu_svm *svm)
{
+ struct kvm_sev_info *sev = to_kvm_sev_info(svm->vcpu.kvm);
struct vmcb *vmcb = svm->vmcb01.ptr;
struct kvm_vcpu *vcpu = &svm->vcpu;
@@ -4464,6 +4465,10 @@ static void sev_es_init_vmcb(struct vcpu_svm *svm)
if (svm->sev_es.vmsa && !svm->sev_es.snp_has_guest_vmsa)
svm->vmcb->control.vmsa_pa = __pa(svm->sev_es.vmsa);
+ if (cpu_feature_enabled(X86_FEATURE_ALLOWED_SEV_FEATURES))
+ svm->vmcb->control.allowed_sev_features = sev->vmsa_features |
+ VMCB_ALLOWED_SEV_FEATURES_VALID;
+
/* Can't intercept CR register access, HV can't modify CR registers */
svm_clr_intercept(svm, INTERCEPT_CR0_READ);
svm_clr_intercept(svm, INTERCEPT_CR4_READ);
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 8abeab91d329..bff6e9c34586 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -3435,6 +3435,8 @@ static void dump_vmcb(struct kvm_vcpu *vcpu)
pr_err("%-20s%016llx\n", "avic_logical_id:", control->avic_logical_id);
pr_err("%-20s%016llx\n", "avic_physical_id:", control->avic_physical_id);
pr_err("%-20s%016llx\n", "vmsa_pa:", control->vmsa_pa);
+ pr_err("%-20s%016llx\n", "allowed_sev_features:", control->allowed_sev_features);
+ pr_err("%-20s%016llx\n", "guest_sev_features:", control->guest_sev_features);
pr_err("VMCB State Save Area:\n");
pr_err("%-5s s: %04x a: %04x l: %08x b: %016llx\n",
"es:",
--
2.43.0
