[Xen-changelog] [xen staging] x86/hvm: always expose x2APIC feature in max HVM cpuid policy

[patchbot@xxxxxxx]

commit 1b4c0be707c524a28f020c584f541c667e6dc78f
Author:     Roger Pau Monne <roger.pau@xxxxxxxxxx>
AuthorDate: Tue Dec 24 11:18:10 2019 +0100
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Thu Jan 16 16:00:24 2020 +0000

    x86/hvm: always expose x2APIC feature in max HVM cpuid policy
    
    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.
    
    This was regressed by c/s 3e0c8272f20 which caused x2APIC not to be enabled
    unilaterally for HVM guests.
    
    Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 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
--
generated by git-patchbot for /home/xen/git/xen.git#staging

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