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authorH. Peter Anvin <hpa@linux.intel.com>2013-07-12 16:48:12 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-08-04 16:50:53 +0800
commit6d7d28443969512be95873d2fb155f4be9261ca5 (patch)
treed158ae61ac6f8e5b18ea0d9da8c16e3353df9fb1 /arch
parent07221c8c2109ae56d9f83cd0644498069ed7cfed (diff)
x86, suspend: Handle CPUs which fail to #GP on RDMSR
commit 5ff560fd48d5b3d82fa0c3aff625c9da1a301911 upstream. There are CPUs which have errata causing RDMSR of a nonexistent MSR to not fault. We would then try to WRMSR to restore the value of that MSR, causing a crash. Specifically, some Pentium M variants would have this problem trying to save and restore the non-existent EFER, causing a crash on resume. Work around this by making sure we can write back the result at suspend time. Huge thanks to Christian Sünkenberg for finding the offending erratum that finally deciphered the mystery. Reported-and-tested-by: Johan Heinrich <onny@project-insanity.org> Debugged-by: Christian Sünkenberg <christian.suenkenberg@student.kit.edu> Acked-by: Rafael J. Wysocki <rjw@sisk.pl> Link: http://lkml.kernel.org/r/51DDC972.3010005@student.kit.edu Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/acpi/sleep.c18
1 files changed, 16 insertions, 2 deletions
diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
index b44577bc974..ec94e11807d 100644
--- a/arch/x86/kernel/acpi/sleep.c
+++ b/arch/x86/kernel/acpi/sleep.c
@@ -48,9 +48,20 @@ int acpi_suspend_lowlevel(void)
#ifndef CONFIG_64BIT
native_store_gdt((struct desc_ptr *)&header->pmode_gdt);
+ /*
+ * We have to check that we can write back the value, and not
+ * just read it. At least on 90 nm Pentium M (Family 6, Model
+ * 13), reading an invalid MSR is not guaranteed to trap, see
+ * Erratum X4 in "Intel Pentium M Processor on 90 nm Process
+ * with 2-MB L2 Cache and Intel® Processor A100 and A110 on 90
+ * nm process with 512-KB L2 Cache Specification Update".
+ */
if (!rdmsr_safe(MSR_EFER,
&header->pmode_efer_low,
- &header->pmode_efer_high))
+ &header->pmode_efer_high) &&
+ !wrmsr_safe(MSR_EFER,
+ header->pmode_efer_low,
+ header->pmode_efer_high))
header->pmode_behavior |= (1 << WAKEUP_BEHAVIOR_RESTORE_EFER);
#endif /* !CONFIG_64BIT */
@@ -61,7 +72,10 @@ int acpi_suspend_lowlevel(void)
}
if (!rdmsr_safe(MSR_IA32_MISC_ENABLE,
&header->pmode_misc_en_low,
- &header->pmode_misc_en_high))
+ &header->pmode_misc_en_high) &&
+ !wrmsr_safe(MSR_IA32_MISC_ENABLE,
+ header->pmode_misc_en_low,
+ header->pmode_misc_en_high))
header->pmode_behavior |=
(1 << WAKEUP_BEHAVIOR_RESTORE_MISC_ENABLE);
header->realmode_flags = acpi_realmode_flags;