[Xen-devel] [PATCH] x86/hvm: always expose x2APIC feature in max HVM cpuid policy

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

On hardware without x2APIC support Xen emulated local APIC will
provide such mode, and hence the feature should be set in the maximum
HVM cpuid policy.

Not exposing it in the maximum policy results in HVM domains not
getting such feature exposed unless it's also supported by the
underlying hardware.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
This is a regression, but I'm not able to identify the commit that
introduced the bogus behavior.
---
 xen/arch/x86/cpuid.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/cpuid.c b/xen/arch/x86/cpuid.c
index 7055509ed6..b1ed33d524 100644
--- a/xen/arch/x86/cpuid.c
+++ b/xen/arch/x86/cpuid.c
@@ -396,10 +396,11 @@ static void __init calculate_hvm_max_policy(void)
         hvm_featureset[i] &= hvm_featuremask[i];
 
     /*
-     * Xen can provide an APIC emulation to HVM guests even if the host's APIC
-     * isn't enabled.
+     * Xen can provide an (x2)APIC emulation to HVM guests even if the host's
+     * (x2)APIC isn't enabled.
      */
     __set_bit(X86_FEATURE_APIC, hvm_featureset);
+    __set_bit(X86_FEATURE_X2APIC, hvm_featureset);
 
     /*
      * On AMD, PV guests are entirely unable to use SYSENTER as Xen runs in
-- 
2.24.1


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