Messages in this thread Patch in this message | | | Date | Wed, 15 Jun 2011 17:28:13 -0700 | From | Greg KH <> | Subject | [17/85] x86, amd: Use _safe() msr access for GartTlbWlk disable code |
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2.6.33-longterm review patch. If anyone has any objections, please let us know.
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From: "Roedel, Joerg" <Joerg.Roedel@amd.com>
commit d47cc0db8fd6011de2248df505fc34990b7451bf upstream.
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> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- arch/x86/kernel/cpu/amd.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
--- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -585,10 +585,13 @@ static void __cpuinit init_amd(struct cp * 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); + } } }
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