[OE-core][PATCH] qemuboot-x86: add qemux86 kvm workaround

[OE-core][PATCH] qemuboot-x86: add qemux86 kvm workaround

[Trevor Gamblin]

[YOCTO #16074]

As per the bug listed, investigation of an intermittent failure with
KVM-enabled qemux86 VMs has shown that there is a possible issue with a
spectre v2 retpoline mitigation when running on hosts with certain Intel
CPUs, e.g. the Intel Ultra 7 265. We have confirmed that disabling the
KVM paravirtualized clock prevents the failure; so for now, avoid it by
specifying '-cpu IvyBridge,kvmclock=off' instead of simply '-cpu
IvyBridge' in qemuboot-x86 for the KVM case.

Note that this issue does not affect qemux86-64.

Signed-off-by: Trevor Gamblin <tgamblin@baylibre.com>
---
 meta/conf/machine/include/x86/qemuboot-x86.inc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/meta/conf/machine/include/x86/qemuboot-x86.inc b/meta/conf/machine/include/x86/qemuboot-x86.inc
index 82ef4a0b73..abdbc12fa1 100644
--- a/meta/conf/machine/include/x86/qemuboot-x86.inc
+++ b/meta/conf/machine/include/x86/qemuboot-x86.inc
@@ -2,7 +2,7 @@
 IMAGE_CLASSES += "qemuboot"
 QB_SMP ?= "-smp 4"
 QB_CPU:x86 ?= "-cpu IvyBridge -machine q35,i8042=off"
-QB_CPU_KVM:x86 ?= "-cpu IvyBridge -machine q35,i8042=off"
+QB_CPU_KVM:x86 ?= "-cpu IvyBridge,kvmclock=off -machine q35,i8042=off"
 
 QB_CPU:x86-64 ?= "-cpu Skylake-Client -machine q35,i8042=off"
 QB_CPU_KVM:x86-64 ?= "-cpu Skylake-Client -machine q35,i8042=off"
-- 
2.53.0