[PATCH 6/6] KVM: SVM: Enable restricted injection for an SEV-SNP guest

Melody Wang
2024-08-07T01:05:27Z

Enable the restricted injection in an SEV-SNP guest by setting the restricted
injection bit in the VMSA SEV features field (SEV_FEATURES[3]) from QEMU.

Add the restricted injection supporting the hypervisor advertised features.

Co-developed-by: Thomas Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Thomas Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Melody Wang <huibo.wang@amd.com>
---
arch/x86/include/asm/cpufeatures.h | 1 +
arch/x86/include/asm/sev-common.h | 1 +
arch/x86/kvm/svm/sev.c | 26 +++++++++++++++++++++++++-
3 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index dd4682857c12..ff8466405409 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -446,6 +446,7 @@
#define X86_FEATURE_SEV_SNP (19*32+ 4) /* "sev_snp" 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_RESTRICTED_INJECTION (19*32+12) /* AMD SEV Restricted Injection */
#define X86_FEATURE_DEBUG_SWAP (19*32+14) /* "debug_swap" AMD SEV-ES full debug state swap support */
#define X86_FEATURE_SVSM (19*32+28) /* "svsm" SVSM present */

diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h
index 98726c2b04f8..f409893ad1a5 100644
--- a/arch/x86/include/asm/sev-common.h
+++ b/arch/x86/include/asm/sev-common.h
@@ -136,6 +136,7 @@ enum psc_op {

#define GHCB_HV_FT_SNP BIT_ULL(0)
#define GHCB_HV_FT_SNP_AP_CREATION BIT_ULL(1)
+#define GHCB_HV_FT_SNP_RINJ (BIT_ULL(2) | GHCB_HV_FT_SNP_AP_CREATION)
#define GHCB_HV_FT_SNP_MULTI_VMPL BIT_ULL(5)

/*
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 87c493bad93a..038a1c8a5ad7 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -39,7 +39,9 @@
#define GHCB_VERSION_DEFAULT 2ULL
#define GHCB_VERSION_MIN 1ULL

-#define GHCB_HV_FT_SUPPORTED (GHCB_HV_FT_SNP | GHCB_HV_FT_SNP_AP_CREATION)
+#define GHCB_HV_FT_SUPPORTED (GHCB_HV_FT_SNP | \
+ GHCB_HV_FT_SNP_AP_CREATION | \
+ GHCB_HV_FT_SNP_RINJ)

/* enable/disable SEV support */
static bool sev_enabled = true;
@@ -56,6 +58,10 @@ module_param_named(sev_snp, sev_snp_enabled, bool, 0444);
/* 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);
+
+/* enable/disable SEV-SNP Restricted Injection support */
+static bool sev_snp_restricted_injection_enabled = true;
+module_param_named(restricted_injection, sev_snp_restricted_injection_enabled, bool, 0444);
static u64 sev_supported_vmsa_features;

#define AP_RESET_HOLD_NONE 0
@@ -3078,6 +3084,12 @@ void __init sev_hardware_setup(void)
sev_supported_vmsa_features = 0;
if (sev_es_debug_swap_enabled)
sev_supported_vmsa_features |= SVM_SEV_FEAT_DEBUG_SWAP;
+
+ if (!sev_snp_enabled || !cpu_feature_enabled(X86_FEATURE_RESTRICTED_INJECTION))
+ sev_snp_restricted_injection_enabled = false;
+
+ if (sev_snp_restricted_injection_enabled)
+ sev_supported_vmsa_features |= SVM_SEV_FEAT_RESTRICTED_INJECTION;
}

void sev_hardware_unsetup(void)
@@ -4555,6 +4567,15 @@ void sev_vcpu_after_set_cpuid(struct vcpu_svm *svm)
sev_es_vcpu_after_set_cpuid(svm);
}

+static void sev_snp_init_vmcb(struct vcpu_svm *svm)
+{
+ struct kvm_sev_info *sev = &to_kvm_svm(svm->vcpu.kvm)->sev_info;
+
+ /* V_NMI is not supported when Restricted Injection is enabled */
+ if (sev->vmsa_features & SVM_SEV_FEAT_RESTRICTED_INJECTION)
+ svm->vmcb->control.int_ctl &= ~V_NMI_ENABLE_MASK;
+}
+
static void sev_es_init_vmcb(struct vcpu_svm *svm)
{
struct vmcb *vmcb = svm->vmcb01.ptr;
@@ -4612,6 +4633,9 @@ static void sev_es_init_vmcb(struct vcpu_svm *svm)
/* Clear intercepts on selected MSRs */
set_msr_interception(vcpu, svm->msrpm, MSR_EFER, 1, 1);
set_msr_interception(vcpu, svm->msrpm, MSR_IA32_CR_PAT, 1, 1);
+
+ if (sev_snp_guest(vcpu->kvm))
+ sev_snp_init_vmcb(svm);
}

void sev_init_vmcb(struct vcpu_svm *svm)
--
2.34.1