From: "Jan Beulich" <JBeulich@suse.com>
To: "Paul Durrant" <paul.durrant@citrix.com>
Cc: Kevin Tian <kevin.tian@intel.com>, Wei Liu <wei.liu2@citrix.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
xen-devel <xen-devel@lists.xenproject.org>,
Brian Woods <brian.woods@amd.com>,
Roger Pau Monne <roger.pau@citrix.com>
Subject: Re: [Xen-devel] [PATCH 2/5] iommu / x86: move call to scan_pci_devices() out of vendor code
Date: Wed, 15 May 2019 00:29:39 -0600 [thread overview]
Message-ID: <5CDBB1D3020000780022F109@prv1-mh.provo.novell.com> (raw)
Message-ID: <20190515062939.JMYR2j69MPCD70udzVYF4jY2aD_EBdIWMYa77kmKNuU@z> (raw)
In-Reply-To: <9a476c95c1fb410b9330c45fa6799b9a@AMSPEX02CL03.citrite.net>
>>> On 14.05.19 at 18:13, <Paul.Durrant@citrix.com> wrote:
>> -----Original Message-----
>> From: Jan Beulich [mailto:JBeulich@suse.com]
>> Sent: 13 May 2019 08:36
>> To: Paul Durrant <Paul.Durrant@citrix.com>
>> Cc: Brian Woods <brian.woods@amd.com>; Suravee Suthikulpanit
> <suravee.suthikulpanit@amd.com>; Andrew
>> Cooper <Andrew.Cooper3@citrix.com>; Roger Pau Monne <roger.pau@citrix.com>; Wei
> Liu
>> <wei.liu2@citrix.com>; Kevin Tian <kevin.tian@intel.com>; xen-devel
> <xen-devel@lists.xenproject.org>
>> Subject: Re: [PATCH 2/5] iommu / x86: move call to scan_pci_devices() out of
> vendor code
>>
>> >>> On 08.05.19 at 15:24, <paul.durrant@citrix.com> wrote:
>> > It's not vendor specific so it shouldn't really be there.
>>
>> Perhaps, but this needs better justification:
>>
>> > --- a/xen/drivers/passthrough/vtd/iommu.c
>> > +++ b/xen/drivers/passthrough/vtd/iommu.c
>> > @@ -2372,10 +2372,6 @@ static int __init vtd_setup(void)
>> > P(iommu_hap_pt_share, "Shared EPT tables");
>> > #undef P
>> >
>> > - ret = scan_pci_devices();
>> > - if ( ret )
>> > - goto error;
>> > -
>> > ret = init_vtd_hw();
>>
>> Even after some looking around, it's not obvious to me that the latter
>> call doesn't depend on PCI devices being known, more specifically
>> segment 0's bus2bridge[] having been filled. Nor can I tell whether
>> there would be some noticeable misbehavior (prior to any guests
>> starting) if there was a dependency and it got broken by the re-
>> ordering.
>
> I don't see any dependency but the code is somewhat tangled. Perhaps it
> would be better to build the PCI topology *before* IOMMU init and then
> iterate over the the devices after init to do the group assignment. I
> certainly can't see anything in the scan as it stands that would need the
> IOMMU to have been initialized.
Ah, yes, that's likely a better model. As to the dependency
aspect: pci_add_device() calls iommu_add_device(). But oddly
enough _scan_pci_devices() calls alloc_pdev(), not
pci_add_device(). So indeed there doesn't look to be any
dependency at present.
Jan
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next prev parent reply other threads:[~2019-05-15 6:30 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-08 13:23 [PATCH 0/5] iommu groups + cleanup Paul Durrant
2019-05-08 13:23 ` [Xen-devel] " Paul Durrant
2019-05-08 13:23 ` [PATCH 1/5] iommu: trivial re-organisation to avoid unnecessary test Paul Durrant
2019-05-08 13:23 ` [Xen-devel] " Paul Durrant
2019-05-13 15:22 ` Jan Beulich
2019-05-13 15:22 ` [Xen-devel] " Jan Beulich
2019-05-08 13:24 ` [PATCH 2/5] iommu / x86: move call to scan_pci_devices() out of vendor code Paul Durrant
2019-05-08 13:24 ` [Xen-devel] " Paul Durrant
2019-05-13 15:35 ` Jan Beulich
2019-05-13 15:35 ` [Xen-devel] " Jan Beulich
2019-05-14 16:13 ` Paul Durrant
2019-05-14 16:13 ` [Xen-devel] " Paul Durrant
2019-05-15 6:29 ` Jan Beulich [this message]
2019-05-15 6:29 ` Jan Beulich
2019-05-08 13:24 ` [PATCH 3/5] iommu: move iommu_get_ops() into common code Paul Durrant
2019-05-08 13:24 ` [Xen-devel] " Paul Durrant
2019-05-13 16:11 ` Jan Beulich
2019-05-13 16:11 ` [Xen-devel] " Jan Beulich
2019-05-14 16:19 ` Paul Durrant
2019-05-14 16:19 ` [Xen-devel] " Paul Durrant
2019-05-14 21:36 ` Julien Grall
2019-05-14 21:36 ` [Xen-devel] " Julien Grall
2019-05-15 6:32 ` Jan Beulich
2019-05-15 6:32 ` [Xen-devel] " Jan Beulich
2019-05-08 13:24 ` [PATCH 4/5] iommu: introduce iommu_groups Paul Durrant
2019-05-08 13:24 ` [Xen-devel] " Paul Durrant
2019-05-15 8:44 ` Roger Pau Monné
2019-05-15 8:44 ` [Xen-devel] " Roger Pau Monné
2019-05-31 13:48 ` Paul Durrant
2019-05-31 13:48 ` [Xen-devel] " Paul Durrant
2019-05-15 14:17 ` Jan Beulich
2019-05-15 14:17 ` [Xen-devel] " Jan Beulich
2019-05-31 13:55 ` Paul Durrant
2019-05-31 13:55 ` [Xen-devel] " Paul Durrant
2019-05-31 14:13 ` Jan Beulich
2019-05-31 14:13 ` [Xen-devel] " Jan Beulich
2019-05-31 14:21 ` Paul Durrant
2019-05-31 14:21 ` [Xen-devel] " Paul Durrant
2019-05-15 14:24 ` Jan Beulich
2019-05-15 14:24 ` [Xen-devel] " Jan Beulich
2019-05-08 13:24 ` [PATCH 5/5] iommu / pci: re-implement XEN_DOMCTL_get_device_group Paul Durrant
2019-05-08 13:24 ` [Xen-devel] " Paul Durrant
2019-05-15 9:06 ` Roger Pau Monné
2019-05-15 9:06 ` [Xen-devel] " Roger Pau Monné
2019-06-03 9:58 ` Paul Durrant
2019-06-03 9:58 ` [Xen-devel] " Paul Durrant
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