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authorRoedel, Joerg <Joerg.Roedel@amd.com>2011-05-19 11:13:39 +0200
committerIngo Molnar <mingo@elte.hu>2011-05-20 12:57:18 +0200
commitd47cc0db8fd6011de2248df505fc34990b7451bf (patch)
treea019570daeba6e6f9ad3410b9adf2d0c2760223b /arch/x86/kernel
parent257313b2a87795e07a0bdf58d0fffbdba8b31051 (diff)
x86, amd: Use _safe() msr access for GartTlbWlk disable code
The workaround for Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=33012 introduced a read and a write to the MC4 mask msr. Unfortunatly this MSR is not emulated by the KVM hypervisor so that the kernel will get a #GP and crashes when applying this workaround when running inside KVM. This issue was reported as: https://bugzilla.kernel.org/show_bug.cgi?id=35132 and is fixed with this patch. The change just let the kernel ignore any #GP it gets while accessing this MSR by using the _safe msr access methods. Reported-by: Török Edwin <edwintorok@gmail.com> Signed-off-by: Joerg Roedel <joerg.roedel@amd.com> Cc: Rafael J. Wysocki <rjw@sisk.pl> Cc: Maciej Rutecki <maciej.rutecki@gmail.com> Cc: Avi Kivity <avi@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: <stable@kernel.org> # .39.x Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/kernel')
-rw-r--r--arch/x86/kernel/cpu/amd.c9
1 files changed, 6 insertions, 3 deletions
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 6f9d1f6063e..8f5cabb3c5b 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -629,10 +629,13 @@ static void __cpuinit init_amd(struct cpuinfo_x86 *c)
* Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=33012
*/
u64 mask;
+ int err;
- rdmsrl(MSR_AMD64_MCx_MASK(4), mask);
- mask |= (1 << 10);
- wrmsrl(MSR_AMD64_MCx_MASK(4), mask);
+ err = rdmsrl_safe(MSR_AMD64_MCx_MASK(4), &mask);
+ if (err == 0) {
+ mask |= (1 << 10);
+ checking_wrmsrl(MSR_AMD64_MCx_MASK(4), mask);
+ }
}
}