[Xen-changelog] [xen stable-4.2] x86: fix boot time APIC mode detection

[patchbot@xxxxxxx]

commit 857e2b43715ba86ee660924cfe1d772fa052c54d
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Fri May 31 12:23:30 2013 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri May 31 12:23:30 2013 +0200

    x86: fix boot time APIC mode detection
    
    current_cpu_data becomes valid only relatively late in the boot
    process, so looking there for a particular feature early in the game
    would generally give the appearance of the feature being unavailable.
    
    Getting this wrong means that at kexec time the system would get
    returned to xAPIC mode, causing disconnect_bsp_APIC() to try to access
    the APIC page, which on systems with x2APIC pre-enabled will never get
    set up.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Keir Fraser <keir@xxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    master commit: 234c4dde2fd4f1182fe1a6bea6bced83fe363007
    master date: 2013-05-23 13:08:32 +0200
---
 xen/arch/x86/apic.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/xen/arch/x86/apic.c b/xen/arch/x86/apic.c
index 50430d2..00b25f0 100644
--- a/xen/arch/x86/apic.c
+++ b/xen/arch/x86/apic.c
@@ -1473,7 +1473,7 @@ enum apic_mode current_local_apic_mode(void)
 
     /* Reading EXTD bit from the MSR is only valid if CPUID
      * says so, else reserved */
-    if ( cpu_has(&current_cpu_data, X86_FEATURE_X2APIC)
+    if ( boot_cpu_has(X86_FEATURE_X2APIC)
          && (msr_contents & MSR_IA32_APICBASE_EXTD) )
         return APIC_MODE_X2APIC;
 
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.2

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