[PATCH v5 5/6] KVM: SVM: Add support for Hypervisor Feature support MSR protocol

Joerg Roedel
2021-10-20T12:44:48Z

From: Brijesh Singh <brijesh.singh@amd.com>

Version 2 of the GHCB specification introduced advertisement of
supported Hypervisor SEV features. This request is required to support
a the GHCB version 2 protocol.

Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
arch/x86/include/uapi/asm/svm.h | 1 +
arch/x86/kvm/svm/sev.c | 23 +++++++++++++++++++++++
2 files changed, 24 insertions(+)

diff --git a/arch/x86/include/uapi/asm/svm.h b/arch/x86/include/uapi/asm/svm.h
index efa969325ede..67cf153fe580 100644
--- a/arch/x86/include/uapi/asm/svm.h
+++ b/arch/x86/include/uapi/asm/svm.h
@@ -108,6 +108,7 @@
#define SVM_VMGEXIT_AP_JUMP_TABLE 0x80000005
#define SVM_VMGEXIT_SET_AP_JUMP_TABLE 0
#define SVM_VMGEXIT_GET_AP_JUMP_TABLE 1
+#define SVM_VMGEXIT_HYPERVISOR_FEATURES 0x8000fffd
#define SVM_VMGEXIT_UNSUPPORTED_EVENT 0x8000ffff

/* Exit code reserved for hypervisor/software use */
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 10af4ac83971..0c673291e905 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -2216,6 +2216,7 @@ static int sev_es_validate_vmgexit(struct vcpu_svm *svm)
case SVM_VMGEXIT_AP_HLT_LOOP:
case SVM_VMGEXIT_AP_JUMP_TABLE:
case SVM_VMGEXIT_UNSUPPORTED_EVENT:
+ case SVM_VMGEXIT_HYPERVISOR_FEATURES:
break;
default:
goto vmgexit_err;
@@ -2423,6 +2424,20 @@ static u64 ghcb_msr_ap_rst_resp(u64 value)
return (u64)GHCB_MSR_AP_RESET_HOLD_RESP | (value << GHCB_DATA_LOW);
}

+/* Hypervisor GHCB Features supported by KVM */
+#define KVM_SUPPORTED_GHCB_HV_FEATURES 0UL
+
+static u64 ghcb_msr_hv_feat_resp(void)
+{
+ u64 msr;
+
+ msr = GHCB_MSR_HV_FT_RESP;
+ msr |= (KVM_SUPPORTED_GHCB_HV_FEATURES << GHCB_DATA_LOW);
+
+ return msr;
+}
+
+
static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm *svm)
{
struct vmcb_control_area *control = &svm->vmcb->control;
@@ -2478,6 +2493,9 @@ static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm *svm)
*/
svm->vmcb->control.ghcb_gpa = ghcb_msr_ap_rst_resp(0);

+ break;
+ case GHCB_MSR_HV_FT_REQ:
+ svm->vmcb->control.ghcb_gpa = ghcb_msr_hv_feat_resp();
break;
case GHCB_MSR_TERM_REQ: {
u64 reason_set, reason_code;
@@ -2591,6 +2609,11 @@ int sev_handle_vmgexit(struct kvm_vcpu *vcpu)
ret = 1;
break;
}
+ case SVM_VMGEXIT_HYPERVISOR_FEATURES:
+ ghcb_set_sw_exit_info_2(ghcb, KVM_SUPPORTED_GHCB_HV_FEATURES);
+
+ ret = 1;
+ break;
case SVM_VMGEXIT_UNSUPPORTED_EVENT:
vcpu_unimpl(vcpu,
"vmgexit: unsupported event - exit_info_1=%#llx, exit_info_2=%#llx\n",
--
2.33.1