[RFC Part2 PATCH 28/30] KVM: SVM: add support to handle Page State Change VMGEXIT

[Brijesh Singh <brijesh.singh@amd.com>]

SEV-SNP VMs can ask the hypervisor to change the page state in the RMP
table to be private or shared using the Page State Change NAE event
as defined in the GHCB specification section 4.1.6.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Wanpeng Li <wanpengli@tencent.com>
Cc: Jim Mattson <jmattson@google.com>
Cc: x86@kernel.org
Cc: kvm@vger.kernel.org
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
---
 arch/x86/kvm/svm/sev.c | 58 ++++++++++++++++++++++++++++++++++++++++++
 arch/x86/kvm/svm/svm.h |  4 +++
 2 files changed, 62 insertions(+)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 8f046b45c424..35e7a7bbf878 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -2141,6 +2141,7 @@ 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_PAGE_STATE_CHANGE:
 		break;
 	default:
 		goto vmgexit_err;
@@ -2425,6 +2426,7 @@ static int __snp_handle_page_state_change(struct kvm_vcpu *vcpu, int op, gpa_t g
 		case SNP_PAGE_STATE_PRIVATE:
 			rc = snp_make_page_private(vcpu, gpa, pfn, level);
 			break;
+		/* TODO: Add USMASH and PSMASH support */
 		default:
 			rc = -EINVAL;
 			break;
@@ -2445,6 +2447,53 @@ static int __snp_handle_page_state_change(struct kvm_vcpu *vcpu, int op, gpa_t g
 	return rc;
 }
 
+static unsigned long snp_handle_page_state_change(struct vcpu_svm *svm, struct ghcb *ghcb)
+{
+	struct snp_page_state_entry *entry;
+	struct kvm_vcpu *vcpu = &svm->vcpu;
+	struct snp_page_state_change *info;
+	unsigned long rc;
+	int level, op;
+	gpa_t gpa;
+
+	if (!sev_snp_guest(vcpu->kvm))
+		return -ENXIO;
+
+	if (!setup_vmgexit_scratch(svm, true, sizeof(ghcb->save.sw_scratch))) {
+		pr_err("vmgexit: scratch area is not setup.\n");
+		return -EINVAL;
+	}
+
+	info = (struct snp_page_state_change *)svm->ghcb_sa;
+	entry = &info->entry[info->header.cur_entry];
+
+	if ((info->header.cur_entry >= SNP_PAGE_STATE_CHANGE_MAX_ENTRY) ||
+	    (info->header.end_entry >= SNP_PAGE_STATE_CHANGE_MAX_ENTRY) ||
+	    (info->header.cur_entry > info->header.end_entry))
+		return VMGEXIT_PAGE_STATE_INVALID_HEADER;
+
+	while (info->header.cur_entry <= info->header.end_entry) {
+		entry = &info->entry[info->header.cur_entry];
+		gpa = gfn_to_gpa(entry->gfn);
+		level = RMP_X86_PG_LEVEL(entry->pagesize);
+		op = entry->operation;
+
+		if (!IS_ALIGNED(gpa, page_level_size(level))) {
+			rc = VMGEXIT_PAGE_STATE_INVALID_ENTRY;
+			goto out;
+		}
+
+		rc = __snp_handle_page_state_change(vcpu, op, gpa, level);
+		if (rc)
+			goto out;
+
+		info->header.cur_entry++;
+	}
+
+out:
+	return rc;
+}
+
 static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm *svm)
 {
 	struct vmcb_control_area *control = &svm->vmcb->control;
@@ -2667,6 +2716,15 @@ int sev_handle_vmgexit(struct vcpu_svm *svm)
 		ret = 1;
 		break;
 	}
+	case SVM_VMGEXIT_PAGE_STATE_CHANGE: {
+		unsigned long rc;
+
+		ret = 1;
+
+		rc = snp_handle_page_state_change(svm, ghcb);
+		ghcb_set_sw_exit_info_2(ghcb, rc);
+		break;
+	}
 	case SVM_VMGEXIT_UNSUPPORTED_EVENT:
 		vcpu_unimpl(&svm->vcpu,
 			    "vmgexit: unsupported event - exit_info_1=%#llx, exit_info_2=%#llx\n",
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 31bc9cc12c44..9fcfceb4d71e 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -600,6 +600,10 @@ void svm_vcpu_unblocking(struct kvm_vcpu *vcpu);
 #define	GHCB_MSR_PAGE_STATE_CHANGE_RSVD_POS	12
 #define	GHCB_MSR_PAGE_STATE_CHANGE_RSVD_MASK	0xfffff
 
+#define VMGEXIT_PAGE_STATE_INVALID_HEADER	0x100000001
+#define VMGEXIT_PAGE_STATE_INVALID_ENTRY	0x100000002
+#define VMGEXIT_PAGE_STATE_FIRMWARE_ERROR(x)	((x & 0xffffffff) | 0x200000000)
+
 #define GHCB_MSR_TERM_REQ		0x100
 #define GHCB_MSR_TERM_REASON_SET_POS	12
 #define GHCB_MSR_TERM_REASON_SET_MASK	0xf
-- 
2.17.1