linux-kernel - [PATCH v14 23/22] [SQUASH] KVM: SEV: Add support to handle GHCB GPA register VMGEXIT

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Date: Tue, 23 Apr 2024 11:21:38 -0500
From: Michael Roth <michael.roth@....com>
To: <kvm@...r.kernel.org>
CC: <linux-coco@...ts.linux.dev>, <linux-mm@...ck.org>,
	<linux-crypto@...r.kernel.org>, <x86@...nel.org>,
	<linux-kernel@...r.kernel.org>, <tglx@...utronix.de>, <mingo@...hat.com>,
	<jroedel@...e.de>, <thomas.lendacky@....com>, <hpa@...or.com>,
	<ardb@...nel.org>, <pbonzini@...hat.com>, <seanjc@...gle.com>,
	<vkuznets@...hat.com>, <jmattson@...gle.com>, <luto@...nel.org>,
	<dave.hansen@...ux.intel.com>, <slp@...hat.com>, <pgonda@...gle.com>,
	<peterz@...radead.org>, <srinivas.pandruvada@...ux.intel.com>,
	<rientjes@...gle.com>, <dovmurik@...ux.ibm.com>, <tobin@....com>,
	<bp@...en8.de>, <vbabka@...e.cz>, <kirill@...temov.name>,
	<ak@...ux.intel.com>, <tony.luck@...el.com>,
	<sathyanarayanan.kuppuswamy@...ux.intel.com>, <alpergun@...gle.com>,
	<jarkko@...nel.org>, <ashish.kalra@....com>, <nikunj.dadhania@....com>,
	<pankaj.gupta@....com>, <liam.merwick@...cle.com>
Subject: [PATCH v14 23/22] [SQUASH] KVM: SEV: Add support to handle GHCB GPA register VMGEXIT

Terminate if an non-SNP guest attempts to register a GHCB page; this
is an SNP-only GHCB request.

Signed-off-by: Michael Roth <michael.roth@....com>
---
 arch/x86/kvm/svm/sev.c | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 1cec466e593b..088eca85a6ac 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -3970,6 +3970,9 @@ static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm *svm)
 				  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,
@@ -3978,6 +3981,9 @@ static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm *svm)
 	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);
 
@@ -4004,12 +4010,7 @@ 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 */
@@ -4020,6 +4021,14 @@ 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)
-- 
2.25.1