[PATCH v4 2/2] KVM: SEV: Restrict userspace return codes for KVM_HC_MAP_GPA_RANGE

[Sagi Shahar <sagis@google.com>]

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.

Reviewed-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Sagi Shahar <sagis@google.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 3f9c1aa39a0a..04076262f087 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -3718,9 +3718,13 @@ 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);
@@ -3811,10 +3815,14 @@ 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 */
 	}
-- 
2.53.0.473.g4a7958ca14-goog