Re: [PATCH] ACPI, APEI, Add APEI _OSC support

Matthew Garrett
2011-06-14T14:52:59Z

On Wed, May 25, 2011 at 02:05:38PM +0800, Huang Ying wrote:

> To gain full APEI power on these machines, a special APEI _OSC needs
> to be evaluated to tell firmware that Linux has full APEI support.
> This patch add the APEI _OSC support.

(snip)

> + static DEFINE_MUTEX(mutex);
> + static int status = APEI_OSC_SETUP_UNKNOWN;
> + static u8 apei_uuid_str[] = "ed855e0c-6c90-47bf-a62a-26de0fc5ad5c";

This is the WHEA UUID, right?

> + u32 capbuf[3];
> + struct acpi_osc_context context = {
> + .uuid_str = apei_uuid_str,
> + .rev = 1,
> + .cap.length = sizeof(capbuf),
> + .cap.pointer = capbuf,
> + };
> +
> + mutex_lock(&mutex);
> + if (status == APEI_OSC_SETUP_UNKNOWN) {
> + capbuf[OSC_QUERY_TYPE] = OSC_QUERY_ENABLE;
> + capbuf[OSC_SUPPORT_TYPE] = 0;
> + capbuf[OSC_CONTROL_TYPE] = 0;
> +
> + if (ACPI_FAILURE(acpi_get_handle(NULL, "\\_SB", &handle))
> + || ACPI_FAILURE(acpi_run_osc(handle, &context))) {
> + pr_err(APEI_PFX "APEI _OSC failed!\n");
> + status = APEI_OSC_SETUP_FAILED;
> + } else {
> + kfree(context.ret.pointer);
> + status = APEI_OSC_SETUP_SUCCEEDED;
> + }
> + }
> + mutex_unlock(&mutex);
> +
> + return status == APEI_OSC_SETUP_SUCCEEDED ? 0 : -EIO;

So we fail if the platform doesn't implement WHEA...

> + rc = apei_osc_setup();
> + if (rc) {
> + ghes_remove(ghes_dev);
> + return rc;
> + }
> +

And then tear down GHES. This seems wrong. A platform could predicate
APEI functionality on the ACPI spec APEI indication (which we currently
don't pass) without implementing WHEA, but with this patch we'd refuse
to enable GHES support? We should probably try both the standard method
and the WHEA method and only disable GHES if both fail.

(Also, are there any other sideeffects of indicating that we support
WHEA?)

--
Matthew Garrett | mjg59@srcf.ucam.org