Merge tag 'for-upstream' of https://gitlab.com/bonzini/qemu into staging

Bugfixes.

# gpg: Signature made Mon 21 Mar 2022 14:57:57 GMT
# gpg:                using RSA key F13338574B662389866C7682BFFBD25F78C7AE83
# gpg:                issuer "pbonzini@redhat.com"
# gpg: Good signature from "Paolo Bonzini <bonzini@gnu.org>" [full]
# gpg:                 aka "Paolo Bonzini <pbonzini@redhat.com>" [full]
# Primary key fingerprint: 46F5 9FBD 57D6 12E7 BFD4  E2F7 7E15 100C CD36 69B1
#      Subkey fingerprint: F133 3857 4B66 2389 866C  7682 BFFB D25F 78C7 AE83

* tag 'for-upstream' of https://gitlab.com/bonzini/qemu

:
  hw/i386/amd_iommu: Fix maybe-uninitialized error with GCC 12
  target/i386: kvm: do not access uninitialized variable on older kernels

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/i386/amd_iommu.c

@@ -913,7 +913,7 @@ static void amdvi_page_walk(AMDVIAddressSpace *as, uint64_t *dte,
         }
 
         /* we are at the leaf page table or page table encodes a huge page */
-        while (level > 0) {
+        do {
             pte_perms = amdvi_get_perms(pte);
             present = pte & 1;
             if (!present || perms != (perms & pte_perms)) {
@@ -932,10 +932,7 @@ static void amdvi_page_walk(AMDVIAddressSpace *as, uint64_t *dte,
             }
             oldlevel = level;
             level = get_pte_translation_mode(pte);
-            if (level == 0x7) {
-                break;
-            }
-        }
+        } while (level > 0 && level < 7);
 
         if (level == 0x7) {
             page_mask = pte_override_page_mask(pte);

target/i386/kvm/kvm.c

@@ -411,6 +411,12 @@ uint32_t kvm_arch_get_supported_cpuid(KVMState *s, uint32_t function,
         }
     } else if (function == 0xd && index == 0 &&
                (reg == R_EAX || reg == R_EDX)) {
+        /*
+         * The value returned by KVM_GET_SUPPORTED_CPUID does not include
+         * features that still have to be enabled with the arch_prctl
+         * system call.  QEMU needs the full value, which is retrieved
+         * with KVM_GET_DEVICE_ATTR.
+         */
         struct kvm_device_attr attr = {
             .group = 0,
             .attr = KVM_X86_XCOMP_GUEST_SUPP,
@@ -419,13 +425,16 @@ uint32_t kvm_arch_get_supported_cpuid(KVMState *s, uint32_t function,
 
         bool sys_attr = kvm_check_extension(s, KVM_CAP_SYS_ATTRIBUTES);
         if (!sys_attr) {
-            warn_report("cannot get sys attribute capabilities %d", sys_attr);
+            return ret;
         }
 
         int rc = kvm_ioctl(s, KVM_GET_DEVICE_ATTR, &attr);
-        if (rc == -1 && (errno == ENXIO || errno == EINVAL)) {
-            warn_report("KVM_GET_DEVICE_ATTR(0, KVM_X86_XCOMP_GUEST_SUPP) "
-                        "error: %d", rc);
+        if (rc < 0) {
+            if (rc != -ENXIO) {
+                warn_report("KVM_GET_DEVICE_ATTR(0, KVM_X86_XCOMP_GUEST_SUPP) "
+                            "error: %d", rc);
+            }
+            return ret;
         }
         ret = (reg == R_EAX) ? bitmask : bitmask >> 32;
     } else if (function == 0x80000001 && reg == R_ECX) {