[PATCH 23/24] KVM: SEV: Turn sev_es_validate_vmgexit() into a dedicated predicate

[Paolo Bonzini]

From: Sean Christopherson <seanjc@xxxxxxxxxx>

Now that sev_es_validate_vmgexit() is only responsible for checking that
all required GHCB fields are marked valid, turn it into a predicate whose
name reflects exactly that.

No functional change intended.

Reviewed-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
Reviewed-by: Michael Roth <michael.roth@xxxxxxx>
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Message-ID: <20260501202250.2115252-24-seanjc@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
 arch/x86/kvm/svm/sev.c | 112 +++++++++++++++--------------------------
 1 file changed, 41 insertions(+), 71 deletions(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 864d6aea544b..bb70df2bf1a4 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -3410,7 +3410,7 @@ static void sev_es_sync_from_ghcb(struct vcpu_svm *svm)
 	memset(ghcb->save.valid_bitmap, 0, sizeof(ghcb->save.valid_bitmap));
 }
 
-static int sev_es_validate_vmgexit(struct vcpu_svm *svm)
+static bool sev_es_are_required_ghcb_fields_valid(struct vcpu_svm *svm)
 {
 	struct vmcb_control_area *control = &svm->vmcb->control;
 	struct kvm_vcpu *vcpu = &svm->vcpu;
@@ -3418,92 +3418,53 @@ static int sev_es_validate_vmgexit(struct vcpu_svm *svm)
 	if (!kvm_ghcb_sw_exit_code_is_valid(svm) ||
 	    !kvm_ghcb_sw_exit_info_1_is_valid(svm) ||
 	    !kvm_ghcb_sw_exit_info_2_is_valid(svm))
-		goto vmgexit_err;
+		return false;
 
 	switch (control->exit_code) {
 	case SVM_EXIT_WRITE_DR7:
-		if (!kvm_ghcb_rax_is_valid(svm))
-			goto vmgexit_err;
-		break;
+		return kvm_ghcb_rax_is_valid(svm);
 	case SVM_EXIT_RDPMC:
-		if (!kvm_ghcb_rcx_is_valid(svm))
-			goto vmgexit_err;
-		break;
+		return kvm_ghcb_rcx_is_valid(svm);
 	case SVM_EXIT_CPUID:
 		if (!kvm_ghcb_rax_is_valid(svm) ||
 		    !kvm_ghcb_rcx_is_valid(svm))
-			goto vmgexit_err;
-		if (vcpu->arch.regs[VCPU_REGS_RAX] == 0xd)
-			if (!kvm_ghcb_xcr0_is_valid(svm))
-				goto vmgexit_err;
-		break;
+			return false;
+
+		return vcpu->arch.regs[VCPU_REGS_RAX] != 0xd ||
+		       kvm_ghcb_xcr0_is_valid(svm);
 	case SVM_EXIT_IOIO:
-		if (control->exit_info_1 & SVM_IOIO_STR_MASK) {
-			if (!kvm_ghcb_sw_scratch_is_valid(svm))
-				goto vmgexit_err;
-		} else {
-			if (!(control->exit_info_1 & SVM_IOIO_TYPE_MASK))
-				if (!kvm_ghcb_rax_is_valid(svm))
-					goto vmgexit_err;
-		}
-		break;
+		if (control->exit_info_1 & SVM_IOIO_STR_MASK)
+			return kvm_ghcb_sw_scratch_is_valid(svm);
+
+		if (!(control->exit_info_1 & SVM_IOIO_TYPE_MASK))
+			return kvm_ghcb_rax_is_valid(svm);
+
+		return true;
 	case SVM_EXIT_MSR:
 		if (!kvm_ghcb_rcx_is_valid(svm))
-			goto vmgexit_err;
-		if (control->exit_info_1) {
-			if (!kvm_ghcb_rax_is_valid(svm) ||
-			    !kvm_ghcb_rdx_is_valid(svm))
-				goto vmgexit_err;
-		}
-		break;
+			return false;
+
+		return !control->exit_info_1 ||
+		       (kvm_ghcb_rax_is_valid(svm) && kvm_ghcb_rdx_is_valid(svm));
 	case SVM_EXIT_VMMCALL:
-		if (!kvm_ghcb_rax_is_valid(svm) ||
-		    !kvm_ghcb_cpl_is_valid(svm))
-			goto vmgexit_err;
-		break;
+		return kvm_ghcb_rax_is_valid(svm) && kvm_ghcb_cpl_is_valid(svm);
 	case SVM_EXIT_MONITOR:
-		if (!kvm_ghcb_rax_is_valid(svm) ||
-		    !kvm_ghcb_rcx_is_valid(svm) ||
-		    !kvm_ghcb_rdx_is_valid(svm))
-			goto vmgexit_err;
-		break;
+		return kvm_ghcb_rax_is_valid(svm) &&
+		       kvm_ghcb_rcx_is_valid(svm) &&
+		       kvm_ghcb_rdx_is_valid(svm);
 	case SVM_EXIT_MWAIT:
-		if (!kvm_ghcb_rax_is_valid(svm) ||
-		    !kvm_ghcb_rcx_is_valid(svm))
-			goto vmgexit_err;
+		return kvm_ghcb_rax_is_valid(svm) && kvm_ghcb_rcx_is_valid(svm);
+	case SVM_VMGEXIT_AP_CREATION:
+		return kvm_ghcb_rax_is_valid(svm) ||
+		       lower_32_bits(control->exit_info_1) == SVM_VMGEXIT_AP_DESTROY;
 		break;
 	case SVM_VMGEXIT_MMIO_READ:
 	case SVM_VMGEXIT_MMIO_WRITE:
-		if (!kvm_ghcb_sw_scratch_is_valid(svm))
-			goto vmgexit_err;
-		break;
-	case SVM_VMGEXIT_AP_CREATION:
-		if (lower_32_bits(control->exit_info_1) != SVM_VMGEXIT_AP_DESTROY)
-			if (!kvm_ghcb_rax_is_valid(svm))
-				goto vmgexit_err;
-		break;
 	case SVM_VMGEXIT_PSC:
-		if (!kvm_ghcb_sw_scratch_is_valid(svm))
-			goto vmgexit_err;
-		break;
+		return kvm_ghcb_sw_scratch_is_valid(svm);
 	default:
-		break;
+		return true;
 	}
-
-	return 0;
-
-vmgexit_err:
-	/*
-	 * Print the exit code even though it may not be marked valid as it
-	 * could help with debugging.
-	 */
-	vcpu_unimpl(vcpu, "vmgexit: exit code %#llx input is not valid\n",
-		    control->exit_code);
-	dump_ghcb(svm);
-	svm_vmgexit_bad_input(svm, GHCB_ERR_MISSING_INPUT);
-
-	/* Resume the guest to "return" the error code. */
-	return 1;
 }
 
 static void __sev_es_unmap_ghcb(struct vcpu_svm *svm)
@@ -4510,9 +4471,17 @@ int sev_handle_vmgexit(struct kvm_vcpu *vcpu)
 		return 1;
 	}
 
-	ret = sev_es_validate_vmgexit(svm);
-	if (ret)
-		return ret;
+	if (!sev_es_are_required_ghcb_fields_valid(svm)) {
+		/*
+		 * Print the exit code even though it may not be marked valid
+		 * as it could help with debugging.
+		 */
+		vcpu_unimpl(vcpu, "vmgexit: exit code %#llx input is not valid\n",
+			    control->exit_code);
+		dump_ghcb(svm);
+		svm_vmgexit_bad_input(svm, GHCB_ERR_MISSING_INPUT);
+		return 1;
+	}
 
 	svm_vmgexit_success(svm, 0);
 
@@ -4599,6 +4568,7 @@ int sev_handle_vmgexit(struct kvm_vcpu *vcpu)
 		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;
+		ret = 0;
 		break;
 	case SVM_VMGEXIT_PSC:
 		ret = setup_vmgexit_scratch(svm, true, sizeof(struct psc_hdr));
-- 
2.54.0