linux-kernel - [PATCH v3 2/2] KVM: SEV: Restrict userspace return codes for KVM_HC_MAP_GPA

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Message-ID: <20260206222829.3758171-3-sagis@google.com>
Date: Fri,  6 Feb 2026 22:28:29 +0000
From: Sagi Shahar <sagis@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, Kiryl Shutsemau <kas@...nel.org>, 
	Rick Edgecombe <rick.p.edgecombe@...el.com>
Cc: Thomas Gleixner <tglx@...nel.org>, Borislav Petkov <bp@...en8.de>, "H. Peter Anvin" <hpa@...or.com>, 
	Michael Roth <michael.roth@....com>, Tom Lendacky <thomas.lendacky@....com>, x86@...nel.org, 
	kvm@...r.kernel.org, linux-kernel@...r.kernel.org, linux-coco@...ts.linux.dev, 
	Sagi Shahar <sagis@...gle.com>
Subject: [PATCH v3 2/2] KVM: SEV: Restrict userspace return codes for KVM_HC_MAP_GPA_RANGE

To align with the updated TDX api that allows userspace to request
that guests retry MAP_GPA operations, make sure that userspace is only
returning EINVAL or EAGAIN as possible error codes.

Signed-off-by: Sagi Shahar <sagis@...gle.com>
---
 arch/x86/kvm/svm/sev.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index f59c65abe3cf..5f78e4c3eb5d 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -3722,9 +3722,13 @@ static int snp_rmptable_psmash(kvm_pfn_t pfn)
 
 static int snp_complete_psc_msr(struct kvm_vcpu *vcpu)
 {
+	u64 hypercall_ret = READ_ONCE(vcpu->run->hypercall.ret);
 	struct vcpu_svm *svm = to_svm(vcpu);
 
-	if (vcpu->run->hypercall.ret)
+	if (!kvm_is_valid_map_gpa_range_ret(hypercall_ret))
+		return -EINVAL;
+
+	if (hypercall_ret)
 		set_ghcb_msr(svm, GHCB_MSR_PSC_RESP_ERROR);
 	else
 		set_ghcb_msr(svm, GHCB_MSR_PSC_RESP);
@@ -3815,10 +3819,14 @@ static void __snp_complete_one_psc(struct vcpu_svm *svm)
 
 static int snp_complete_one_psc(struct kvm_vcpu *vcpu)
 {
+	u64 hypercall_ret = READ_ONCE(vcpu->run->hypercall.ret);
 	struct vcpu_svm *svm = to_svm(vcpu);
 	struct psc_buffer *psc = svm->sev_es.ghcb_sa;
 
-	if (vcpu->run->hypercall.ret) {
+	if (!kvm_is_valid_map_gpa_range_ret(hypercall_ret))
+		return -EINVAL;
+
+	if (hypercall_ret) {
 		snp_complete_psc(svm, VMGEXIT_PSC_ERROR_GENERIC);
 		return 1; /* resume guest */
 	}
-- 
2.53.0.rc2.204.g2597b5adb4-goog