Re: [PATCH v11 0/4] set VSESR_EL2 by user space and support NOTIFY_SEI notification

[James Morse <james.morse@arm.com>]

Hi Dongjiu Geng,

On 09/04/18 22:36, Dongjiu Geng wrote:
> 1. Detect whether KVM can set set guest SError syndrome
> 2. Support to Set VSESR_EL2 and inject SError by user space.
> 3. Support live migration to keep SError pending state and VSESR_EL2 value.
> 4. ACPI 6.1 adds support for NOTIFY_SEI as a GHES notification mechanism, so support this
>    notification in software, KVM or kernel ARCH code call handle_guest_sei() to let ACP driver
>    to handle this notification.

Please don't post code during the merge-window, will this apply to v4.17-rc1? We
can't know until its tagged.


This series is doing two separate things, please split it into two series.

But on the ACPI front: I don't see how any OS can support your NOTIFY_SEI when
firmware is ignoring the normal world's PSTATE.A.

The latest lobe of that discussion was on the list here:
https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1611496.html


As it is, we would need to spot SError being delivered while SError is masked,
spray nasty messages about firmware being horrifically buggy, then panic(). For
a corrected error, this looks bad, but its preferable to letting firmware
silently overwrite the exception registers, causing linux to spin through the
vectors 'eret' with all exceptions masked.
I still think its best to wait for firmware that does the right thing.


Thanks,

James