Re: [PATCH V3 06/10] acpi: apei: panic OS with fatal error status block

[Baicar, Tyler]

Hello Suzuki,

On 10/13/2016 7:00 AM, Suzuki K Poulose wrote:
> On 07/10/16 22:31, Tyler Baicar wrote:
> > From: "Jonathan (Zhixiong) Zhang" <zjzhang@xxxxxxxxxxxxxx>
> >
> > Even if an error status block's severity is fatal, the kernel does not
> > honor the severity level and panic.
> >
> > With the firmware first model, the platform could inform the OS about a
> > fatal hardware error through the non-NMI GHES notification type. The OS
> > should panic when a hardware error record is received with this
> > severity.
> >
> > Call panic() after CPER data in error status block is printed if
> > severity is fatal, before each error section is handled.
> >
> > Signed-off-by: Jonathan (Zhixiong) Zhang <zjzhang@xxxxxxxxxxxxxx>
> > ---
> >  drivers/acpi/apei/ghes.c | 10 ++++++++--
> >  1 file changed, 8 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
> > index 28d5a09..36894c8 100644
> > --- a/drivers/acpi/apei/ghes.c
> > +++ b/drivers/acpi/apei/ghes.c
> > @@ -141,6 +141,8 @@ static unsigned long ghes_estatus_pool_size_request;
> >  static struct ghes_estatus_cache 
> > *ghes_estatus_caches[GHES_ESTATUS_CACHES_SIZE];
> >  static atomic_t ghes_estatus_cache_alloced;
> >
> > +static int ghes_panic_timeout __read_mostly = 30;
> > +
> >  static int ghes_ioremap_init(void)
> >  {
> >      ghes_ioremap_area = __get_vm_area(PAGE_SIZE * GHES_IOREMAP_PAGES,
> > @@ -715,6 +717,12 @@ static int ghes_proc(struct ghes *ghes)
> >          if (ghes_print_estatus(NULL, ghes->generic, ghes->estatus))
> >              ghes_estatus_cache_add(ghes->generic, ghes->estatus);
> >      }
> > +    if (ghes_severity(ghes->estatus->error_severity) >= 
> > GHES_SEV_PANIC) {
> > +        if (panic_timeout == 0)
> > +            panic_timeout = ghes_panic_timeout;
> > +        panic("Fatal hardware error!");
>
> I think there is a chance that we might miss the o/p of 
> ghes_print_estatus() as we use
> no pfx, and it could default to the normal loglevel and would never 
> get printed
> if panic() is encountered before it. On the other hand, there is 
> already a
> __ghes_panic() which does similar stuff. Is there a way we could reuse
> (may be even parts of) it ? Or at least use KERN_EMERG for the 
> ghes_print_estatus(),
> if the severity could result in panic() ?
__ghes_panic() does additional handling which we do not want to do here. 
I could make the following a helper function so it is not duplicated though:

if (panic_timeout == 0)
    panic_timeout = ghes_panic_timeout;
panic("Fatal hardware error!");

The pfx is actually being calculated already in __ghes_print_estatus():

        if (pfx == NULL) {
                if (ghes_severity(estatus->error_severity) <=
                    GHES_SEV_CORRECTED)
                        pfx = KERN_WARNING;
                else
                        pfx = KERN_ERR;
        }

From ghes.h:

enum {
        GHES_SEV_NO = 0x0,
        GHES_SEV_CORRECTED = 0x1,
        GHES_SEV_RECOVERABLE = 0x2,
        GHES_SEV_PANIC = 0x3,
};

This will make the pfx KERN_ERR for the case of a panic.

Thanks,
Tyler
> Cheers
> Suzuki

--
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project.