This is a note to let you know that I've just added the patch titled
x86, suspend: Handle CPUs which fail to #GP on RDMSR
to the 3.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-suspend-handle-cpus-which-fail-to-gp-on-rdmsr.patch
and it can be found in the queue-3.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 5ff560fd48d5b3d82fa0c3aff625c9da1a301911 Mon Sep 17 00:00:00 2001
From: "H. Peter Anvin" <[email protected]>
Date: Fri, 12 Jul 2013 16:48:12 -0700
Subject: x86, suspend: Handle CPUs which fail to #GP on RDMSR
From: "H. Peter Anvin" <[email protected]>
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 <[email protected]>
Debugged-by: Christian Sünkenberg <[email protected]>
Acked-by: Rafael J. Wysocki <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
arch/x86/kernel/acpi/sleep.c | 18 ++++++++++++++++--
1 file changed, 16 insertions(+), 2 deletions(-)
--- 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;
Patches currently in stable-queue which might be from [email protected] are
queue-3.10/x86-suspend-handle-cpus-which-fail-to-gp-on-rdmsr.patch
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