From: Brijesh Singh <brijesh.singh@xxxxxxx>
SEV-SNP guests are required to perform a GHCB GPA registration. Before
using a GHCB GPA for a vCPU the first time, a guest must register the
vCPU GHCB GPA. If hypervisor can work with the guest requested GPA then
it must respond back with the same GPA otherwise return -1.
On VMEXIT, verify that the GHCB GPA matches with the registered value.
If a mismatch is detected, then abort the guest.
Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
Signed-off-by: Ashish Kalra <ashish.kalra@xxxxxxx>
Signed-off-by: Michael Roth <michael.roth@xxxxxxx>
Message-ID: <20240501085210.2213060-9-michael.roth@xxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
arch/x86/include/asm/sev-common.h | 8 ++++++
arch/x86/kvm/svm/sev.c | 48 +++++++++++++++++++++++++++----
arch/x86/kvm/svm/svm.h | 7 +++++
3 files changed, 57 insertions(+), 6 deletions(-)
diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h
index 5a8246dd532f..1006bfffe07a 100644
--- a/arch/x86/include/asm/sev-common.h
+++ b/arch/x86/include/asm/sev-common.h
@@ -59,6 +59,14 @@
#define GHCB_MSR_AP_RESET_HOLD_RESULT_POS 12
#define GHCB_MSR_AP_RESET_HOLD_RESULT_MASK GENMASK_ULL(51, 0)
+/* Preferred GHCB GPA Request */
+#define GHCB_MSR_PREF_GPA_REQ 0x010
+#define GHCB_MSR_GPA_VALUE_POS 12
+#define GHCB_MSR_GPA_VALUE_MASK GENMASK_ULL(51, 0)
+
+#define GHCB_MSR_PREF_GPA_RESP 0x011
+#define GHCB_MSR_PREF_GPA_NONE 0xfffffffffffff
+
/* GHCB GPA Register */
#define GHCB_MSR_REG_GPA_REQ 0x012
#define GHCB_MSR_REG_GPA_REQ_VAL(v) \
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 208bb8170d3f..557f462fde04 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -3540,6 +3540,32 @@ static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm *svm)
set_ghcb_msr_bits(svm, GHCB_MSR_HV_FT_RESP,
GHCB_MSR_INFO_MASK, GHCB_MSR_INFO_POS);
break;
+ case GHCB_MSR_PREF_GPA_REQ:
+ if (!sev_snp_guest(vcpu->kvm))
+ goto out_terminate;
+
+ set_ghcb_msr_bits(svm, GHCB_MSR_PREF_GPA_NONE, GHCB_MSR_GPA_VALUE_MASK,
+ GHCB_MSR_GPA_VALUE_POS);
+ set_ghcb_msr_bits(svm, GHCB_MSR_PREF_GPA_RESP, GHCB_MSR_INFO_MASK,
+ GHCB_MSR_INFO_POS);
+ break;
+ case GHCB_MSR_REG_GPA_REQ: {
+ u64 gfn;
+
+ if (!sev_snp_guest(vcpu->kvm))
+ goto out_terminate;
+
+ gfn = get_ghcb_msr_bits(svm, GHCB_MSR_GPA_VALUE_MASK,
+ GHCB_MSR_GPA_VALUE_POS);
+
+ svm->sev_es.ghcb_registered_gpa = gfn_to_gpa(gfn);
+
+ set_ghcb_msr_bits(svm, gfn, GHCB_MSR_GPA_VALUE_MASK,
+ GHCB_MSR_GPA_VALUE_POS);
+ set_ghcb_msr_bits(svm, GHCB_MSR_REG_GPA_RESP, GHCB_MSR_INFO_MASK,
+ GHCB_MSR_INFO_POS);
+ break;
+ }
case GHCB_MSR_TERM_REQ: {
u64 reason_set, reason_code;
@@ -3552,12 +3578,7 @@ static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm *svm)
pr_info("SEV-ES guest requested termination: %#llx:%#llx\n",
reason_set, reason_code);
- vcpu->run->exit_reason = KVM_EXIT_SYSTEM_EVENT;
- vcpu->run->system_event.type = KVM_SYSTEM_EVENT_SEV_TERM;
- vcpu->run->system_event.ndata = 1;
- vcpu->run->system_event.data[0] = control->ghcb_gpa;
-
- return 0;
+ goto out_terminate;
}
default:
/* Error, keep GHCB MSR value as-is */
@@ -3568,6 +3589,14 @@ static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm *svm)
control->ghcb_gpa, ret);
return ret;
+
+out_terminate:
+ vcpu->run->exit_reason = KVM_EXIT_SYSTEM_EVENT;
+ vcpu->run->system_event.type = KVM_SYSTEM_EVENT_SEV_TERM;
+ vcpu->run->system_event.ndata = 1;
+ vcpu->run->system_event.data[0] = control->ghcb_gpa;
+
+ return 0;
}
int sev_handle_vmgexit(struct kvm_vcpu *vcpu)
@@ -3603,6 +3632,13 @@ int sev_handle_vmgexit(struct kvm_vcpu *vcpu)
trace_kvm_vmgexit_enter(vcpu->vcpu_id, svm->sev_es.ghcb);
sev_es_sync_from_ghcb(svm);
+
+ /* SEV-SNP guest requires that the GHCB GPA must be registered */
+ if (sev_snp_guest(svm->vcpu.kvm) && !ghcb_gpa_is_registered(svm, ghcb_gpa)) {
+ vcpu_unimpl(&svm->vcpu, "vmgexit: GHCB GPA [%#llx] is not registered.\n", ghcb_gpa);
+ return -EINVAL;
+ }
+
ret = sev_es_validate_vmgexit(svm);
if (ret)
return ret;
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 305772d36490..202ac5494c19 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -209,6 +209,8 @@ struct vcpu_sev_es_state {
u32 ghcb_sa_len;
bool ghcb_sa_sync;
bool ghcb_sa_free;
+
+ u64 ghcb_registered_gpa;
};
struct vcpu_svm {
@@ -362,6 +364,11 @@ static __always_inline bool sev_snp_guest(struct kvm *kvm)
#endif
}
+static inline bool ghcb_gpa_is_registered(struct vcpu_svm *svm, u64 val)
+{
+ return svm->sev_es.ghcb_registered_gpa == val;
+}
+
static inline void vmcb_mark_all_dirty(struct vmcb *vmcb)
{
vmcb->control.clean = 0;
--
2.25.1
