| From d47cc0db8fd6011de2248df505fc34990b7451bf Mon Sep 17 00:00:00 2001 |
| From: "Roedel, Joerg" <Joerg.Roedel@amd.com> |
| Date: Thu, 19 May 2011 11:13:39 +0200 |
| Subject: x86, amd: Use _safe() msr access for GartTlbWlk disable code |
| MIME-Version: 1.0 |
| Content-Type: text/plain; charset=UTF-8 |
| Content-Transfer-Encoding: 8bit |
| |
| 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); |
| + } |
| } |
| } |
| |