From: Jan Beulich <jbeulich@suse.com>
To: "Roger Pau Monné" <roger.pau@citrix.com>
Cc: xen-devel@lists.xenproject.org,
Stanislav Spassov <stanspas@amazon.de>,
Chao Gao <chao.gao@intel.com>
Subject: Re: [Xen-devel] [PATCH] pci: clear host_maskall field on assign
Date: Tue, 8 Oct 2019 16:21:56 +0200 [thread overview]
Message-ID: <1319dfd6-052c-39c4-aa29-d79fa9600829@suse.com> (raw)
In-Reply-To: <20191008141615.GF66437@Air-de-Roger>
On 08.10.2019 16:16, Roger Pau Monné wrote:
> On Tue, Oct 08, 2019 at 03:32:25PM +0200, Jan Beulich wrote:
>> On 08.10.2019 15:14, Roger Pau Monné wrote:
>>> On Tue, Oct 08, 2019 at 01:28:49PM +0200, Jan Beulich wrote:
>>>> On 08.10.2019 13:09, Roger Pau Monné wrote:
>>>>> Given that as you correctly point out maskall is unset after device
>>>>> reset, I feel that option 4 is the best one since it matches the state
>>>>> of the hardware after reset.
>>>>
>>>> Right, that's the variant coming closest to what hardware state
>>>> ought to be at that point. We'd need to double check that the
>>>> per-entry mask bits are all set at that point.
>>>
>>> I'm not saying such check is not worth doing, but why do it in this
>>> case but not when also clearing the maskall (in msix_capability_init)
>>> when called from prepare_msix?
>>
>> By "double check" I meant inspect the source, not to add checking logic.
>
> Oh, I implied you wanted to iterate over all entries and check that
> the mask bit is set for each.
>
> It's my understanding that Xen relies on dom0 having done a device
> reset before it being assigned, which masks all entries. I've checked
> the pciback code and the reset is performed when the device is
> assigned to dom0 (ie: guest shutdown or hot-unplug), and hence when
> the device is assigned to a different domain the state of it should be
> the after reset one.
>
> I can add a comment in assign_device that Xen expects the device state
> to be the after reset one, and hence host_maskall = guest_maskall =
> false and all entries should have the mask bit set.
Yes please.
Jan
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next prev parent reply other threads:[~2019-10-08 14:22 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-02 10:49 [Xen-devel] [PATCH] pci: clear host_maskall field on assign Roger Pau Monne
2019-10-02 13:33 ` Jan Beulich
2019-10-08 9:23 ` Roger Pau Monné
2019-10-08 9:42 ` Jan Beulich
2019-10-08 11:09 ` Roger Pau Monné
2019-10-08 11:28 ` Jan Beulich
2019-10-08 13:14 ` Roger Pau Monné
2019-10-08 13:32 ` Jan Beulich
2019-10-08 14:16 ` Roger Pau Monné
2019-10-08 14:21 ` Jan Beulich [this message]
2019-10-04 23:58 ` Chao Gao
2019-10-07 7:38 ` Jan Beulich
2019-10-08 6:18 ` Chao Gao
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