From: Roman Bolshakov <r.bolshakov@yadro.com>

virQEMUCapsFormatCache/virQEMUCapsLoadCache adds/reads KVM CPUs to/from
capabilities cache regardless of QEMU_CAPS_KVM. That can cause undesired
side-effects when KVM CPUs are present in the cache on a platform that
doesn't support it, e.g. macOS or Linux without KVM support.

Signed-off-by: Roman Bolshakov <r.bolshakov@yadro.com>
Signed-off-by: Andrea Bolognani <abologna@redhat.com>
Tested-by: Brad Laue <brad@brad-x.com>
---
 src/qemu/qemu_capabilities.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
index a71d3b912f..c2d56dfc9d 100644
--- a/src/qemu/qemu_capabilities.c
+++ b/src/qemu/qemu_capabilities.c
@@ -4423,8 +4423,11 @@ virQEMUCapsLoadCache(virArch hostArch,
             return -1;
     }
 
-    if (virQEMUCapsLoadAccel(qemuCaps, ctxt, VIR_DOMAIN_VIRT_KVM) < 0 ||
-        virQEMUCapsLoadAccel(qemuCaps, ctxt, VIR_DOMAIN_VIRT_QEMU) < 0)
+    if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_KVM) &&
+        virQEMUCapsLoadAccel(qemuCaps, ctxt, VIR_DOMAIN_VIRT_KVM) < 0) {
+        return -1;
+    }
+    if (virQEMUCapsLoadAccel(qemuCaps, ctxt, VIR_DOMAIN_VIRT_QEMU) < 0)
         return -1;
 
     if (virQEMUCapsParseGIC(qemuCaps, ctxt) < 0)
@@ -4433,7 +4436,8 @@ virQEMUCapsLoadCache(virArch hostArch,
     if (virQEMUCapsParseSEVInfo(qemuCaps, ctxt) < 0)
         return -1;
 
-    virQEMUCapsInitHostCPUModel(qemuCaps, hostArch, VIR_DOMAIN_VIRT_KVM);
+    if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_KVM))
+        virQEMUCapsInitHostCPUModel(qemuCaps, hostArch, VIR_DOMAIN_VIRT_KVM);
     virQEMUCapsInitHostCPUModel(qemuCaps, hostArch, VIR_DOMAIN_VIRT_QEMU);
 
     if (virXPathBoolean("boolean(./kvmSupportsNesting)", ctxt) > 0)
@@ -4666,7 +4670,8 @@ virQEMUCapsFormatCache(virQEMUCaps *qemuCaps)
     virBufferAsprintf(&buf, "<arch>%s</arch>\n",
                       virArchToString(qemuCaps->arch));
 
-    virQEMUCapsFormatAccel(qemuCaps, &buf, VIR_DOMAIN_VIRT_KVM);
+    if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_KVM))
+        virQEMUCapsFormatAccel(qemuCaps, &buf, VIR_DOMAIN_VIRT_KVM);
     virQEMUCapsFormatAccel(qemuCaps, &buf, VIR_DOMAIN_VIRT_QEMU);
 
     for (i = 0; i < qemuCaps->ngicCapabilities; i++) {
@@ -5520,7 +5525,8 @@ virQEMUCapsNewForBinaryInternal(virArch hostArch,
     qemuCaps->libvirtCtime = virGetSelfLastChanged();
     qemuCaps->libvirtVersion = LIBVIR_VERSION_NUMBER;
 
-    virQEMUCapsInitHostCPUModel(qemuCaps, hostArch, VIR_DOMAIN_VIRT_KVM);
+    if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_KVM))
+        virQEMUCapsInitHostCPUModel(qemuCaps, hostArch, VIR_DOMAIN_VIRT_KVM);
     virQEMUCapsInitHostCPUModel(qemuCaps, hostArch, VIR_DOMAIN_VIRT_QEMU);
 
     if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_KVM)) {
-- 
2.34.1

On Mon, Jan 17, 2022 at 11:52:42AM +0100, Andrea Bolognani wrote:
> From: Roman Bolshakov <r.bolshakov@yadro.com>
> 
> virQEMUCapsFormatCache/virQEMUCapsLoadCache adds/reads KVM CPUs to/from
> capabilities cache regardless of QEMU_CAPS_KVM. That can cause undesired
> side-effects when KVM CPUs are present in the cache on a platform that
> doesn't support it, e.g. macOS or Linux without KVM support.
> 
> Signed-off-by: Roman Bolshakov <r.bolshakov@yadro.com>
> Signed-off-by: Andrea Bolognani <abologna@redhat.com>
> Tested-by: Brad Laue <brad@brad-x.com>
> ---
>  src/qemu/qemu_capabilities.c | 16 +++++++++++-----
>  1 file changed, 11 insertions(+), 5 deletions(-)

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>


Regards,
Daniel
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