Re: [PATCH] x86, MCE, AMD: save IA32_MCi_STATUS before machine_check_poll() resets it

Chen Yucong
2014-09-30T00:39:51Z

On Mon, 2014-09-29 at 14:05 +0200, Borislav Petkov wrote:
> > machine_check_poll() will reset IA32_MCi_STATUS register to zero.
> > So we need to save the content of IA32_MCi_STATUS MSRs before
> > calling machine_check_poll() for logging threshold interrupt event.
> >
> > mce_setup() does not gather the content of IA32_MCG_STATUS, so it
> > should be read explicitly.
> >
> > Signed-off-by: Chen Yucong <slaoub@gmail.com>
> > ---
> > arch/x86/kernel/cpu/mcheck/mce_amd.c | 13 ++++++++++++-
> > 1 file changed, 12 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/x86/kernel/cpu/mcheck/mce_amd.c
> b/arch/x86/kernel/cpu/mcheck/mce_amd.c
> > index f8c56bd..9148b4d 100644
> > --- a/arch/x86/kernel/cpu/mcheck/mce_amd.c
> > +++ b/arch/x86/kernel/cpu/mcheck/mce_amd.c
> > @@ -275,6 +275,12 @@ static void amd_threshold_interrupt(void)
> >
> > mce_setup(&m);
> >
> > + /*
> > + * mce_setup() can't gather the content of IA32_MCG_STATUS,
> > + * so it should be read explicitly.
> > + */
>
> No need for that comment.
>
> > + rdmsrl(MSR_IA32_MCG_STATUS, m.mcgstatus);
> > +
> > /* assume first bank caused it */
> > for (bank = 0; bank < mca_cfg.banks; ++bank) {
> > if (!(per_cpu(bank_map, m.cpu) & (1 << bank)))
> > @@ -305,6 +311,12 @@ static void amd_threshold_interrupt(void)
> > (high & MASK_LOCKED_HI))
> > continue;
> >
> > + /*
> > + * machine_check_poll() will reset
> IA32_MCi_STATUS
> > + * register to zero, save it for use later.
> > + */
> > + rdmsrl(MSR_IA32_MCx_STATUS(bank), m.status);
>
> Actually, to be more future-proof, I'd like to do the AMD-specific
> logging first, i.e. before machine_check_poll() so that any future
> changes there don't influence what we do in mce_amd.c.
>
> So please move the machine_check_poll() call behind the
>
> if (high & MASK_OVERFLOW_HI) {
machine_check_poll() will scan all banks, so I think we can move it out
of the loop body.

thx!
cyc

From: Chen Yucong

machine_check_poll() will reset IA32_MCi_STATUS register to zero.
So we need to save the content of IA32_MCi_STATUS MSRs before
calling machine_check_poll() for logging threshold interrupt event.

mce_setup() does not gather the content of IA32_MCG_STATUS, so it
should be read explicitly. And we also need to save MSR_IA32_MCx_ADDR
if MCI_STATUS_ADDRV bit field is valid.

Signed-off-by: Chen Yucong <slaoub@gmail.com>
---
arch/x86/kernel/cpu/mcheck/mce_amd.c | 21 +++++++++++++--------
1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kernel/cpu/mcheck/mce_amd.c b/arch/x86/kernel/cpu/mcheck/mce_amd.c
index f8c56bd..f5a5beb 100644
--- a/arch/x86/kernel/cpu/mcheck/mce_amd.c
+++ b/arch/x86/kernel/cpu/mcheck/mce_amd.c
@@ -274,6 +274,7 @@ static void amd_threshold_interrupt(void)
struct mce m;

mce_setup(&m);
+ rdmsrl(MSR_IA32_MCG_STATUS, m.mcgstatus);

/* assume first bank caused it */
for (bank = 0; bank < mca_cfg.banks; ++bank) {
@@ -305,24 +306,28 @@ static void amd_threshold_interrupt(void)
(high & MASK_LOCKED_HI))
continue;

- /*
- * Log the machine check that caused the threshold
- * event.
- */
- machine_check_poll(MCP_TIMESTAMP,
- this_cpu_ptr(&mce_poll_banks));
-
if (high & MASK_OVERFLOW_HI) {
rdmsrl(address, m.misc);
rdmsrl(MSR_IA32_MCx_STATUS(bank), m.status);
+ if (m.status & MCI_STATUS_ADDRV)
+ rdmsrl(MSR_IA32_MCx_ADDR(bank), m.addr);
m.bank = K8_MCE_THRESHOLD_BASE
+ bank * NR_BLOCKS
+ block;
mce_log(&m);
- return;
+
+ wrmsrl(MSR_IA32_MCx_STATUS(bank), 0);
+ goto log_mcheck;
}
}
}
+
+log_mcheck:
+ /*
+ * Log the machine check that caused the threshold event.
+ */
+ machine_check_poll(MCP_TIMESTAMP,
+ this_cpu_ptr(&mce_poll_banks));
}

/*
--
1.7.10.4