KVM: SEV: use mutex guard in snp_handle_guest_req()

Simplify the error paths in snp_handle_guest_req() by using a mutex
guard, allowing early return instead of using gotos.

Signed-off-by: Carlos López <clopez@suse.de>
Link: https://patch.msgid.link/20260120201013.3931334-8-clopez@suse.de
Link: https://patch.msgid.link/20260310234829.2608037-20-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 1cb9aa9f748cf86daa496533b80174c909b9b2ac..4bf7b2c6b148e22bd81da22856daacff606ee00b 100644 (file)
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -4171,12 +4171,10 @@ static int snp_handle_guest_req(struct vcpu_svm *svm, gpa_t req_gpa, gpa_t resp_
        if (!is_sev_snp_guest(&svm->vcpu))
                return -EINVAL;
 
-       mutex_lock(&sev->guest_req_mutex);
+       guard(mutex)(&sev->guest_req_mutex);
 
-       if (kvm_read_guest(kvm, req_gpa, sev->guest_req_buf, PAGE_SIZE)) {
-               ret = -EIO;
-               goto out_unlock;
-       }
+       if (kvm_read_guest(kvm, req_gpa, sev->guest_req_buf, PAGE_SIZE))
+               return -EIO;
 
        data.gctx_paddr = __psp_pa(sev->snp_context);
        data.req_paddr = __psp_pa(sev->guest_req_buf);
@@ -4189,21 +4187,16 @@ static int snp_handle_guest_req(struct vcpu_svm *svm, gpa_t req_gpa, gpa_t resp_
         */
        ret = sev_issue_cmd(kvm, SEV_CMD_SNP_GUEST_REQUEST, &data, &fw_err);
        if (ret && !fw_err)
-               goto out_unlock;
+               return ret;
 
-       if (kvm_write_guest(kvm, resp_gpa, sev->guest_resp_buf, PAGE_SIZE)) {
-               ret = -EIO;
-               goto out_unlock;
-       }
+       if (kvm_write_guest(kvm, resp_gpa, sev->guest_resp_buf, PAGE_SIZE))
+               return -EIO;
 
        /* No action is requested *from KVM* if there was a firmware error. */
        svm_vmgexit_no_action(svm, SNP_GUEST_ERR(0, fw_err));
 
-       ret = 1; /* resume guest */
-
-out_unlock:
-       mutex_unlock(&sev->guest_req_mutex);
-       return ret;
+       /* resume guest */
+       return 1;
 }
 
 static int snp_req_certs_err(struct vcpu_svm *svm, u32 vmm_error)