Re: [Xen-devel] [PATCH 1/3] Revert "x86/vvmx: fix virtual interrupt injection when Ack on exit control is used"

[Jan Beulich <jbeulich@suse.com>]

On 24.03.2020 06:41, Tian, Kevin wrote:
>> From: Roger Pau Monné <roger.pau@citrix.com>
>> Sent: Monday, March 23, 2020 10:49 PM
>>
>> On Mon, Mar 23, 2020 at 09:09:59AM +0100, Jan Beulich wrote:
>>> On 20.03.2020 20:07, Roger Pau Monne wrote:
>>>> This reverts commit f96e1469ad06b61796c60193daaeb9f8a96d7458.
>>>>
>>>> The commit is wrong, as the whole point of nvmx_update_apicv is to
>>>> update the guest interrupt status field when the Ack on exit VMEXIT
>>>> control feature is enabled.
>>>>
>>>> Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
>>>
>>> Before anyone gets to look at the other two patches, should this
>>> be thrown in right away?
>>
>> I would like if possible get a confirmation from Kevin (or anyone
>> else) that my understanding is correct. I find the nested code very
>> confusing, and I've already made a mistake while trying to fix it.
>> That being said, this was spotted by osstest as introducing a
>> regression, so I guess it's safe to just toss it in now.
>>
>> FWIW patch 2/3 attempts to provide a description of my understanding
>> of how nvmx_update_apicv works.
>>
> 
> I feel it is not good to take this patch alone, as it was introduced to fix
> another problem. W/o understanding whether the whole series can
> fix both old and new problems, we may risk putting nested interrupt
> logic in an even worse state...

Well, okay, I'll wait then, but it would seem to me that reverting
wouldn't put us in a worse state than we were in before that change
was put in.

Jan