linux-kernel - Re: [PATCH v5 3/3] vfio/pci: Decouple PCI_COMMAND_MEMORY bit checks from is

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Date:   Wed, 23 Sep 2020 10:51:36 +0200
From:   Pierre Morel <pmorel@...ux.ibm.com>
To:     Alex Williamson <alex.williamson@...hat.com>,
        Matthew Rosato <mjrosato@...ux.ibm.com>
Cc:     bhelgaas@...gle.com, schnelle@...ux.ibm.com, mpe@...erman.id.au,
        oohall@...il.com, cohuck@...hat.com, kevin.tian@...el.com,
        hca@...ux.ibm.com, gor@...ux.ibm.com, borntraeger@...ibm.com,
        linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, linux-pci@...r.kernel.org
Subject: Re: [PATCH v5 3/3] vfio/pci: Decouple PCI_COMMAND_MEMORY bit checks
 from is_virtfn



On 2020-09-22 18:40, Alex Williamson wrote:
> On Mon, 21 Sep 2020 08:43:29 -0400
> Matthew Rosato <mjrosato@...ux.ibm.com> wrote:
> 
>> On 9/10/20 10:59 AM, Matthew Rosato wrote:
>>> While it is true that devices with is_virtfn=1 will have a Memory Space
>>> Enable bit that is hard-wired to 0, this is not the only case where we
>>> see this behavior -- For example some bare-metal hypervisors lack
>>> Memory Space Enable bit emulation for devices not setting is_virtfn
>>> (s390). Fix this by instead checking for the newly-added
>>> no_command_memory bit which directly denotes the need for
>>> PCI_COMMAND_MEMORY emulation in vfio.
>>>
>>> Fixes: abafbc551fdd ("vfio-pci: Invalidate mmaps and block MMIO access on disabled memory")
>>> Signed-off-by: Matthew Rosato <mjrosato@...ux.ibm.com>
>>> Reviewed-by: Niklas Schnelle <schnelle@...ux.ibm.com>
>>> Reviewed-by: Pierre Morel <pmorel@...ux.ibm.com>
>>
>> Polite ping on this patch as the other 2 have now received maintainer
>> ACKs or reviews.  I'm concerned about this popping up in distros as
>> abafbc551fdd was a CVE fix.  Related, see question from the cover:
>>
>> - Restored the fixes tag to patch 3 (but the other 2 patches are
>>     now pre-reqs -- cc stable 5.8?)
> 
> I've got these queued in my local branch which I'll push to next for
> v5.10.  I'm thinking that perhaps the right thing would be to add the
> fixes tag to all three patches, otherwise I could see that the PCI/VF
> change might get picked as a dependency, but not the s390 specific one.
> Does this sound correct to everyone?  Thanks,
> 
> Alex
> 
sound correct for me.
Thanks.

Pierre

-- 
Pierre Morel
IBM Lab Boeblingen