[PATCH] KVM: SVM: Propagate error from snp_guest_req_init() to userspace

[PATCH] KVM: SVM: Propagate error from snp_guest_req_init() to userspace

[Sean Christopherson]

If snp_guest_req_init() fails, return the provided error code up the
stack to userspace, e.g. so that userspace can log that KVM_SEV_INIT2
failed, as opposed to some random operation later in VM setup failing
because SNP wasn't actually enabled for the VM.

Note, KVM itself doesn't consult the return value from __sev_guest_init(),
i.e. the fallout is purely that userspace may be confused.

Fixes: 88caf544c930 ("KVM: SEV: Provide support for SNP_GUEST_REQUEST NAE event")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/r/202410192220.MeTyHPxI-lkp@intel.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/svm/sev.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index c6c852485900..9cfa953088ce 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -450,8 +450,11 @@ static int __sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp,
 		goto e_free;
 
 	/* This needs to happen after SEV/SNP firmware initialization. */
-	if (vm_type == KVM_X86_SNP_VM && snp_guest_req_init(kvm))
-		goto e_free;
+	if (vm_type == KVM_X86_SNP_VM) {
+		ret = snp_guest_req_init(kvm);
+		if (ret)
+			goto e_free;
+	}
 
 	INIT_LIST_HEAD(&sev->regions_list);
 	INIT_LIST_HEAD(&sev->mirror_vms);

base-commit: e466901b947d529f7b091a3b00b19d2bdee206ee
-- 
2.47.0.163.g1226f6d8fa-goog

Re: [PATCH] KVM: SVM: Propagate error from snp_guest_req_init() to userspace

[Sean Christopherson]

On Thu, 31 Oct 2024 13:32:14 -0700, Sean Christopherson wrote:
> If snp_guest_req_init() fails, return the provided error code up the
> stack to userspace, e.g. so that userspace can log that KVM_SEV_INIT2
> failed, as opposed to some random operation later in VM setup failing
> because SNP wasn't actually enabled for the VM.
> 
> Note, KVM itself doesn't consult the return value from __sev_guest_init(),
> i.e. the fallout is purely that userspace may be confused.
> 
> [...]

Applied to kvm-x86 fixes (yesterday, I forgot to send the thank you mail).

[1/1] KVM: SVM: Propagate error from snp_guest_req_init() to userspace
      https://github.com/kvm-x86/linux/commit/e5d253c60e96

--
https://github.com/kvm-x86/linux/tree/next