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

From: Baicar, Tyler
Date: Thu Oct 13 2016 - 19:41:52 EST

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

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) <=
pfx = KERN_ERR;

From ghes.h:

enum {
GHES_SEV_NO = 0x0,

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



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