From: Jan Beulich Date: Thu, 23 May 2013 11:08:32 +0000 (+0200) Subject: x86: fix boot time APIC mode detection X-Git-Tag: 4.3.0-rc3~2^2~1 X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=234c4dde2fd4f1182fe1a6bea6bced83fe363007;p=people%2Fiwj%2Fxen.git 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 Acked-by: Keir Fraser Reviewed-by: Andrew Cooper --- diff --git a/xen/arch/x86/apic.c b/xen/arch/x86/apic.c index b28f5ed431..a52a0e881d 100644 --- a/xen/arch/x86/apic.c +++ b/xen/arch/x86/apic.c @@ -1474,7 +1474,7 @@ 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(¤t_cpu_data, X86_FEATURE_X2APIC) + if ( boot_cpu_has(X86_FEATURE_X2APIC) && (msr_contents & MSR_IA32_APICBASE_EXTD) ) return APIC_MODE_X2APIC;