linux-kernel - Re: [PATCH v11 0/4] set VSESR_EL2 by user space and support NOTIFY

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Date:   Thu, 12 Apr 2018 14:09:35 +0800
From:   gengdongjiu <gengdongjiu@...wei.com>
To:     James Morse <james.morse@....com>
CC:     <rkrcmar@...hat.com>, <corbet@....net>,
        <christoffer.dall@...aro.org>, <marc.zyngier@....com>,
        <linux@...linux.org.uk>, <catalin.marinas@....com>,
        <rjw@...ysocki.net>, <bp@...en8.de>, <lenb@...nel.org>,
        <kvm@...r.kernel.org>, <linux-doc@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <kvmarm@...ts.cs.columbia.edu>, <linux-acpi@...r.kernel.org>,
        <devel@...ica.org>, <huangshaoyu@...wei.com>,
        <zhengxiang9@...wei.com>
Subject: Re: [PATCH v11 0/4] set VSESR_EL2 by user space and support
 NOTIFY_SEI notification

Hi James，
   thanks for this mail.

On 2018/4/10 22:15, James Morse wrote:
> 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.
I do not know when it is merge-window. About the apply version, it does not have limited.

> 
> 
> This series is doing two separate things, please split it into two series.
OK, thanks!

> 
> 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
I have replied the mail.
I still have some questions that need to clarify with you.
After clarification, we will follow that.
The question is in the reply of this mail "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.
Let us  discuss that in another mail.
In a summary, I think firmware follow below rule can be OK, right?
1. The exception came from the EL that SError should be routed to(according to hcr_EL2.{AMO, TGE}),but PSTATE.A was set, EL3 firmware can't deliver SError;
2. The exception came from the EL that SError should not be routed to(according to hcr_EL2.{AMO, TGE}),even though the PSTATE.A was set,EL3 firmware still deliver SError

> 
> 
> Thanks,
> 
> James
> 
> .
>