debuggers.hg

changeset 20999:220e4996f0e8

Mask AMD CPUID masks in software before writing them to the MSRs

Mask AMD CPUID masks in software before writing them to the MSRs.
Setting bits in the CPUID mask MSR that are not set in the unmasked
CPUID response can cause those bits to be set in the masked response.
Avoid that by explicitly masking in software.

Signed-off-by: Tim Deegan <Tim.Deegan@citrix.com>
author Keir Fraser <keir.fraser@citrix.com>
date Wed Feb 17 12:05:45 2010 +0000 (2010-02-17)
parents 50ea24db1f88
children b4041e7bbe1b
files xen/arch/x86/cpu/amd.c
line diff
     1.1 --- a/xen/arch/x86/cpu/amd.c	Wed Feb 17 12:04:50 2010 +0000
     1.2 +++ b/xen/arch/x86/cpu/amd.c	Wed Feb 17 12:05:45 2010 +0000
     1.3 @@ -130,6 +130,14 @@ static void __devinit set_cpuidmask(stru
     1.4  		return;
     1.5  	}
     1.6  
     1.7 +        /* Setting bits in the CPUID mask MSR that are not set in the
     1.8 +         * unmasked CPUID response can cause those bits to be set in the
     1.9 +         * masked response.  Avoid that by explicitly masking in software. */
    1.10 +        feat_ecx &= cpuid_ecx(0x00000001);
    1.11 +        feat_edx &= cpuid_edx(0x00000001);
    1.12 +        extfeat_ecx &= cpuid_ecx(0x80000001);
    1.13 +        extfeat_edx &= cpuid_edx(0x80000001);
    1.14 +
    1.15  	status = set_mask;
    1.16  	printk("Writing CPUID feature mask ECX:EDX -> %08Xh:%08Xh\n", 
    1.17  	       feat_ecx, feat_edx);