Received-SPF: Pass (protection.outlook.com: domain of nvidia.com designates
 216.228.118.232 as permitted sender) receiver=protection.outlook.com;
 client-ip=216.228.118.232; helo=mail.nvidia.com; pr=C
Date:   Thu, 9 Feb 2023 11:54:07 -0800
From:   Nicolin Chen <nicolinc@nvidia.com>
To:     Eric Farman <farman@linux.ibm.com>
CC:     <jgg@nvidia.com>, <kevin.tian@intel.com>, <joro@8bytes.org>,
        <will@kernel.org>, <robin.murphy@arm.com>,
        <alex.williamson@redhat.com>, <shuah@kernel.org>,
        <yi.l.liu@intel.com>, <linux-kernel@vger.kernel.org>,
        <iommu@lists.linux.dev>, <kvm@vger.kernel.org>,
        <linux-kselftest@vger.kernel.org>, <baolu.lu@linux.intel.com>,
        Matthew Rosato <mjrosato@linux.ibm.com>
Subject: Re: [PATCH v2 03/10] iommufd: Create access in
 vfio_iommufd_emulated_bind()
Message-ID: <Y+VPXwjMhgWe/c0m@Asurada-Nvidia>
References: <cover.1675802050.git.nicolinc@nvidia.com>
 <6083ba9a3c1d92baf1f324d4748333d80d3de830.1675802050.git.nicolinc@nvidia.com>
 <c5f5b03420367dc4280cc54c36dbe03fb34fffa0.camel@linux.ibm.com>
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Disposition: inline
In-Reply-To: <c5f5b03420367dc4280cc54c36dbe03fb34fffa0.camel@linux.ibm.com>
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 09 Feb 2023 19:54:17.7778
 (UTC)
X-MS-Exchange-CrossTenant-Network-Message-Id: eb61232b-18a6-4535-07b3-08db0ad76dd0
X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a
X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.118.232];Helo=[mail.nvidia.com]
X-MS-Exchange-CrossTenant-AuthSource: DS1PEPF0000E63D.namprd02.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Anonymous
X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem
X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW3PR12MB4410
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Thu, Feb 09, 2023 at 01:58:47PM -0500, Eric Farman wrote:
> External email: Use caution opening links or attachments
> 
> 
> On Tue, 2023-02-07 at 13:17 -0800, Nicolin Chen wrote:
> ...snip...
> > diff --git a/drivers/vfio/iommufd.c b/drivers/vfio/iommufd.c
> > index 026f81a87dd7..dc9feab73db7 100644
> > --- a/drivers/vfio/iommufd.c
> > +++ b/drivers/vfio/iommufd.c
> > @@ -141,10 +141,19 @@ static const struct iommufd_access_ops
> > vfio_user_ops = {
> >  int vfio_iommufd_emulated_bind(struct vfio_device *vdev,
> >                                struct iommufd_ctx *ictx, u32
> > *out_device_id)
> >  {
> > +       struct iommufd_access *user;
> > +
> >         lockdep_assert_held(&vdev->dev_set->lock);
> >
> > -       vdev->iommufd_ictx = ictx;
> >         iommufd_ctx_get(ictx);
> > +       user = iommufd_access_create(vdev->iommufd_ictx,
> > &vfio_user_ops, vdev);
> > +       if (IS_ERR(user)) {
> > +               iommufd_ctx_put(vdev->iommufd_ictx);
> 
> Matthew noticed a vfio-ccw and -ap regression that blames this patch.
> 
> Probably both the iommufd_access_create() and iommufd_ctx_put() calls
> want the ictx variable itself, instead of the (uninitialized) pointer
> in the vfio_device. (At least that gets -ccw and -ap working again.)

Oops. Yes, it should be:

	iommufd_ctx_get(ictx);
	user = iommufd_access_create(ictx, &vfio_user_ops, vdev);
	if (IS_ERR(user)) {
		iommufd_ctx_put(ictx);

Will fix in v3.

Thanks!
Nic