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From: Max Gurtovoy <mgurtovoy@nvidia.com>
To: Jason Gunthorpe <jgg@nvidia.com>,
	Alex Williamson <alex.williamson@redhat.com>
Cc: <cohuck@redhat.com>, <kvm@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>, <aviadye@nvidia.com>,
	<oren@nvidia.com>, <shahafs@nvidia.com>, <parav@nvidia.com>,
	<artemp@nvidia.com>, <kwankhede@nvidia.com>, <ACurrid@nvidia.com>,
	<cjia@nvidia.com>, <yishaih@nvidia.com>, <kevin.tian@intel.com>,
	<hch@infradead.org>, <targupta@nvidia.com>,
	<shameerali.kolothum.thodi@huawei.com>, <liulongfang@huawei.com>,
	<yan.y.zhao@intel.com>
Subject: Re: [PATCH 09/11] PCI: add matching checks for driver_override binding
Date: Thu, 17 Jun 2021 02:28:36 +0300	[thread overview]
Message-ID: <cd95b92c-a23b-03a7-1dd3-9554b9d22955@nvidia.com> (raw)
In-Reply-To: <20210616003417.GH1002214@nvidia.com>


On 6/16/2021 3:34 AM, Jason Gunthorpe wrote:
> On Tue, Jun 15, 2021 at 06:22:45PM -0600, Alex Williamson wrote:
>> On Tue, 15 Jun 2021 20:32:57 -0300
>> Jason Gunthorpe <jgg@nvidia.com> wrote:
>>
>>> On Tue, Jun 15, 2021 at 05:22:42PM -0600, Alex Williamson wrote:
>>>
>>>>>> b) alone is a functional, runtime difference.
>>>>> I would state b) differently:
>>>>>
>>>>> b) Ignore the driver-override-only match entries in the ID table.
>>>> No, pci_match_device() returns NULL if a match is found that is marked
>>>> driver-override-only and a driver_override is not specified.  That's
>>>> the same as no match at all.  We don't then go on to search past that
>>>> match in the table, we fail to bind the driver.  That's effectively an
>>>> anti-match when there's no driver_override on the device.
>>> anti-match isn't the intention. The deployment will have match tables
>>> where all entires are either flags=0 or are driver-override-only.
>> I'd expect pci-pf-stub to have one of each, an any-id with
>> override-only flag and the one device ID currently in the table with
>> no flag.
> Oh Hum. Actually I think this shows the anti-match behavior is
> actually a bug.. :(
>
> For something like pci_pf_stub_whitelist, if we add a
> driver_override-only using the PCI any id then it effectively disables
> new_id completely because the match search will alway find the
> driver_override match first and stop searching. There is no chance to
> see things new_id adds.

Actually the dynamic table is the first table the driver search. So 
new_id works exactly the same AFAIU.

But you're right for static mixed table (I assumed that this will never 
happen I guess).

If we put the any_id_override id before the non_override AMAZON device 
entry in the pci-pf-stub we'll fail with the matching to the AMAZON device.

What about the bellow untested addition (also remove condition c):

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index 296de7bc9dc9..2d46f6cd96f7 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -136,7 +136,7 @@ static const struct pci_device_id 
*pci_match_device(struct pci_driver *drv,
                                                     struct pci_dev *dev)
  {
         struct pci_dynid *dynid;
-       const struct pci_device_id *found_id = NULL;
+       const struct pci_device_id *found_id = NULL, *ids;

         /* When driver_override is set, only bind to the matching driver */
         if (dev->driver_override && strcmp(dev->driver_override, 
drv->name))
@@ -155,8 +155,8 @@ static const struct pci_device_id 
*pci_match_device(struct pci_driver *drv,
         if (found_id)
                 return found_id;

-       found_id = pci_match_id(drv->id_table, dev);
-       if (found_id) {
+       ids = drv->id_table;
+       while ((found_id = pci_match_id(ids, dev))) {
                 /*
                  * if we found id in the static table, we must fulfill the
                  * matching flags (i.e. if PCI_ID_F_DRIVER_OVERRIDE flag is
@@ -164,17 +164,19 @@ static const struct pci_device_id 
*pci_match_device(struct pci_driver *drv,
                  */
                 bool is_driver_override =
                         (found_id->flags & PCI_ID_F_DRIVER_OVERRIDE) != 0;
-               if ((is_driver_override && !dev->driver_override) ||
-                   (dev->driver_override && !is_driver_override))
-                       return NULL;
-       } else if (dev->driver_override) {
-               /*
-                * if we didn't find suitable id in the static table,
-                * driver_override will still , send a dummy id
-                */
-               found_id = &pci_device_id_any;
+               if (is_driver_override && !dev->driver_override)
+                       ids = found_id++; /* continue searching */
+               else
+                       break;
         }

+       /*
+        * if no static match, driver_override will always match, send a 
dummy
+        * id.
+        */
+       if (!found_id && dev->driver_override)
+               found_id = &pci_device_id_any;
+
         return found_id;
  }

diff --git a/drivers/pci/pci-pf-stub.c b/drivers/pci/pci-pf-stub.c
index 45855a5e9fca..49544ba9a7af 100644
--- a/drivers/pci/pci-pf-stub.c
+++ b/drivers/pci/pci-pf-stub.c
@@ -19,6 +19,7 @@
   */
  static const struct pci_device_id pci_pf_stub_whitelist[] = {
         { PCI_VDEVICE(AMAZON, 0x0053) },
+       { PCI_DEVICE_FLAGS(PCI_ANY_ID, PCI_ANY_ID, 
PCI_ID_F_STUB_DRIVER_OVERRIDE) }, /* match all by default (override) */
         /* required last entry */
         { 0 }
  };


>
> We have to fix this patch so flags isn't an anti-match to make it work
> without user regression.
>
> Jason

  reply	other threads:[~2021-06-16 23:28 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-03 16:07 [RFC PATCH v4 00/11] Introduce vfio-pci-core subsystem Max Gurtovoy
2021-06-03 16:07 ` [PATCH 01/11] vfio-pci: rename vfio_pci.c to vfio_pci_core.c Max Gurtovoy
2021-06-03 16:08 ` [PATCH 02/11] vfio-pci: rename vfio_pci_private.h to vfio_pci_core.h Max Gurtovoy
2021-06-03 16:08 ` [PATCH 03/11] vfio-pci: rename vfio_pci_device to vfio_pci_core_device Max Gurtovoy
2021-06-03 16:08 ` [PATCH 04/11] vfio-pci: rename ops functions to fit core namings Max Gurtovoy
2021-06-03 16:08 ` [PATCH 05/11] vfio-pci: include vfio header in vfio_pci_core.h Max Gurtovoy
2021-06-03 16:08 ` [PATCH 06/11] vfio-pci: introduce vfio_pci.c Max Gurtovoy
2021-06-03 16:08 ` [PATCH 07/11] vfio-pci: move igd initialization to vfio_pci.c Max Gurtovoy
2021-06-03 16:08 ` [PATCH 08/11] PCI: add flags field to pci_device_id structure Max Gurtovoy
2021-06-03 16:08 ` [PATCH 09/11] PCI: add matching checks for driver_override binding Max Gurtovoy
2021-06-08 21:26   ` Alex Williamson
2021-06-08 22:45     ` Jason Gunthorpe
2021-06-09  1:27       ` Alex Williamson
2021-06-09  9:26         ` Max Gurtovoy
2021-06-13  8:19         ` Max Gurtovoy
2021-06-14  5:40           ` Christoph Hellwig
2021-06-14  8:18             ` Max Gurtovoy
2021-06-14 15:27               ` Christoph Hellwig
2021-06-14 16:01                 ` Jason Gunthorpe
2021-06-14 16:15                   ` Christoph Hellwig
2021-06-14 16:33                     ` Jason Gunthorpe
2021-06-14 18:42           ` Alex Williamson
2021-06-14 23:12             ` Max Gurtovoy
2021-06-15 15:00               ` Alex Williamson
2021-06-15 15:04                 ` Jason Gunthorpe
2021-06-15 16:20                   ` Alex Williamson
2021-06-15 20:42                     ` Jason Gunthorpe
2021-06-15 21:59                       ` Alex Williamson
2021-06-15 23:00                         ` Jason Gunthorpe
2021-06-15 23:22                           ` Alex Williamson
2021-06-15 23:32                             ` Jason Gunthorpe
2021-06-16  0:22                               ` Alex Williamson
2021-06-16  0:34                                 ` Jason Gunthorpe
2021-06-16 23:28                                   ` Max Gurtovoy [this message]
2021-06-16 23:33                                     ` Jason Gunthorpe
2021-06-16 23:42                                       ` Max Gurtovoy
2021-06-16 23:44                                         ` Jason Gunthorpe
2021-06-16 23:51                                           ` Max Gurtovoy
2021-06-16 23:56                                             ` Jason Gunthorpe
2021-06-20 14:46                                               ` Max Gurtovoy
2021-06-03 16:08 ` [PATCH 10/11] vfio-pci: introduce vfio_pci_core subsystem driver Max Gurtovoy
2021-06-08 21:26   ` Alex Williamson
2021-06-09  9:29     ` Max Gurtovoy
2021-06-03 16:08 ` [PATCH 11/11] mlx5-vfio-pci: add new vfio_pci driver for mlx5 devices Max Gurtovoy
2021-07-30  7:53 ` [RFC PATCH v4 00/11] Introduce vfio-pci-core subsystem Shameerali Kolothum Thodi
2021-07-30 11:55   ` Jason Gunthorpe

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