linux-kernel - [PATCH v13 07/26] KVM: SEV: Add GHCB handling for Hypervisor Feature Support requests

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Date: Thu, 18 Apr 2024 14:41:14 -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>, Brijesh Singh
	<brijesh.singh@....com>
Subject: [PATCH v13 07/26] KVM: SEV: Add GHCB handling for Hypervisor Feature Support requests

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

Version 2 of the GHCB specification introduced advertisement of features
that are supported by the Hypervisor.

Now that KVM supports version 2 of the GHCB specification, bump the
maximum supported protocol version.

Signed-off-by: Brijesh Singh <brijesh.singh@....com>
Signed-off-by: Ashish Kalra <ashish.kalra@....com>
Signed-off-by: Michael Roth <michael.roth@....com>
---
 arch/x86/include/asm/sev-common.h |  2 ++
 arch/x86/kvm/svm/sev.c            | 16 +++++++++++++++-
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h
index 01261f7054ad..5a8246dd532f 100644
--- a/arch/x86/include/asm/sev-common.h
+++ b/arch/x86/include/asm/sev-common.h
@@ -101,6 +101,8 @@ enum psc_op {
 /* GHCB Hypervisor Feature Request/Response */
 #define GHCB_MSR_HV_FT_REQ		0x080
 #define GHCB_MSR_HV_FT_RESP		0x081
+#define GHCB_MSR_HV_FT_POS		12
+#define GHCB_MSR_HV_FT_MASK		GENMASK_ULL(51, 0)
 #define GHCB_MSR_HV_FT_RESP_VAL(v)			\
 	/* GHCBData[63:12] */				\
 	(((u64)(v) & GENMASK_ULL(63, 12)) >> 12)
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 6e31cb408dd8..1d2264e93afe 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -33,9 +33,11 @@
 #include "cpuid.h"
 #include "trace.h"
 
-#define GHCB_VERSION_MAX	1ULL
+#define GHCB_VERSION_MAX	2ULL
 #define GHCB_VERSION_MIN	1ULL
 
+#define GHCB_HV_FT_SUPPORTED	GHCB_HV_FT_SNP
+
 /* enable/disable SEV support */
 static bool sev_enabled = true;
 module_param_named(sev, sev_enabled, bool, 0444);
@@ -2701,6 +2703,7 @@ 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_HV_FEATURES:
 		break;
 	default:
 		reason = GHCB_ERR_INVALID_EVENT;
@@ -2961,6 +2964,12 @@ static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm *svm)
 				  GHCB_MSR_INFO_MASK,
 				  GHCB_MSR_INFO_POS);
 		break;
+	case GHCB_MSR_HV_FT_REQ:
+		set_ghcb_msr_bits(svm, GHCB_HV_FT_SUPPORTED,
+				  GHCB_MSR_HV_FT_MASK, GHCB_MSR_HV_FT_POS);
+		set_ghcb_msr_bits(svm, GHCB_MSR_HV_FT_RESP,
+				  GHCB_MSR_INFO_MASK, GHCB_MSR_INFO_POS);
+		break;
 	case GHCB_MSR_TERM_REQ: {
 		u64 reason_set, reason_code;
 
@@ -3085,6 +3094,11 @@ int sev_handle_vmgexit(struct kvm_vcpu *vcpu)
 		ret = 1;
 		break;
 	}
+	case SVM_VMGEXIT_HV_FEATURES:
+		ghcb_set_sw_exit_info_2(svm->sev_es.ghcb, GHCB_HV_FT_SUPPORTED);
+
+		ret = 1;
+		break;
 	case SVM_VMGEXIT_UNSUPPORTED_EVENT:
 		vcpu_unimpl(vcpu,
 			    "vmgexit: unsupported event - exit_info_1=%#llx, exit_info_2=%#llx\n",
-- 
2.25.1