linux-kernel - Re: [PATCH v3 1/1] KVM: s390: pv: fix race when making a page secure

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Message-ID: <9f4d8c72-7bd9-4388-9442-3c84cd0a4558@redhat.com>
Date: Tue, 4 Mar 2025 10:45:40 +0100
From: David Hildenbrand <david@...hat.com>
To: Claudio Imbrenda <imbrenda@...ux.ibm.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-s390@...r.kernel.org, frankja@...ux.ibm.com, borntraeger@...ibm.com,
 nrb@...ux.ibm.com, seiden@...ux.ibm.com, nsg@...ux.ibm.com,
 schlameuss@...ux.ibm.com, hca@...ux.ibm.com
Subject: Re: [PATCH v3 1/1] KVM: s390: pv: fix race when making a page secure

On 04.03.25 10:21, Claudio Imbrenda wrote:
> On Fri, 28 Feb 2025 22:15:04 +0100
> David Hildenbrand <david@...hat.com> wrote:
> 
>> On 27.02.25 14:09, Claudio Imbrenda wrote:
>>> Holding the pte lock for the page that is being converted to secure is
>>> needed to avoid races. A previous commit removed the locking, which
>>> caused issues. Fix by locking the pte again.
>>>
>>> Fixes: 5cbe24350b7d ("KVM: s390: move pv gmap functions into kvm")
>>> Reported-by: David Hildenbrand <david@...hat.com>
>>> Signed-off-by: Claudio Imbrenda <imbrenda@...ux.ibm.com>
>>
>> Tested with shmem / memory-backend-memfd that ends up using large folios
>> / THPs.
>>
>> Tested-by: David Hildenbrand <david@...hat.com>
>> Reviewed-by: David Hildenbrand <david@...hat.com>
>>
>> Two comments below.
> 
> I will need to send a v4, unfortunately there are other issues with this
> patch (as you have probably noticed by now as well)

I ran into some weird KVM_PV_VERIFY issues a couple of times, but did 
not find the root cause so far.

Is that what you are seeing? (and what is the root cause? :) )

-- 
Cheers,

David / dhildenb