From: Nicolin Chen <nicolinc@nvidia.com>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: <kevin.tian@intel.com>, <corbet@lwn.net>, <will@kernel.org>,
<joro@8bytes.org>, <suravee.suthikulpanit@amd.com>,
<robin.murphy@arm.com>, <dwmw2@infradead.org>,
<baolu.lu@linux.intel.com>, <shuah@kernel.org>,
<linux-kernel@vger.kernel.org>, <iommu@lists.linux.dev>,
<linux-arm-kernel@lists.infradead.org>,
<linux-kselftest@vger.kernel.org>, <linux-doc@vger.kernel.org>,
<eric.auger@redhat.com>, <jean-philippe@linaro.org>,
<mdf@kernel.org>, <mshavit@google.com>,
<shameerali.kolothum.thodi@huawei.com>, <smostafa@google.com>,
<ddutile@redhat.com>, <yi.l.liu@intel.com>,
<patches@lists.linux.dev>
Subject: Re: [PATCH v5 06/14] iommufd: Add IOMMUFD_OBJ_VEVENTQ and IOMMUFD_CMD_VEVENTQ_ALLOC
Date: Mon, 13 Jan 2025 11:18:51 -0800 [thread overview]
Message-ID: <Z4VnG2PSeH0MCfGs@Asurada-Nvidia> (raw)
In-Reply-To: <20250113191225.GS5556@nvidia.com>
On Mon, Jan 13, 2025 at 03:12:25PM -0400, Jason Gunthorpe wrote:
> On Fri, Jan 10, 2025 at 01:58:21PM -0800, Nicolin Chen wrote:
> > Hmm, it seems that I haven't got your first narrative straight..
> >
> > Would you mind elaborate "copy_to_user() can block while waiting
> > on a page fault"? When would this happen?
>
> copy_to_user() is a sleeping function that sleeps if the user memory
> is non-present. So userspace can cause copy_to_user to copy to
> anything, including memory that is non-present and will take along
> time to page fault in. Eg perhaps by abusing userfaultfd.
>
> We should not allow userspace to globally DOS the iommu driver this
> way.
>
> So do not hold locks that are also held by the HW event path across
> copy_to_user().
I see. Thanks for explaining. I will add a patch fixing the fault
read() and change the veventq read() accordingly.
Nicolin
next prev parent reply other threads:[~2025-01-13 19:21 UTC|newest]
Thread overview: 77+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-07 17:10 [PATCH v5 00/14] iommufd: Add vIOMMU infrastructure (Part-3: vEVENTQ) Nicolin Chen
2025-01-07 17:10 ` [PATCH v5 01/14] iommufd: Keep OBJ/IOCTL lists in an alphabetical order Nicolin Chen
2025-01-10 6:26 ` Tian, Kevin
2025-01-10 17:25 ` Jason Gunthorpe
2025-01-14 19:29 ` Jason Gunthorpe
2025-01-07 17:10 ` [PATCH v5 02/14] iommufd/fault: Add an iommufd_fault_init() helper Nicolin Chen
2025-01-10 17:25 ` Jason Gunthorpe
2025-01-07 17:10 ` [PATCH v5 03/14] iommufd/fault: Move iommufd_fault_iopf_handler() to header Nicolin Chen
2025-01-10 17:25 ` Jason Gunthorpe
2025-01-07 17:10 ` [PATCH v5 04/14] iommufd: Abstract an iommufd_eventq from iommufd_fault Nicolin Chen
2025-01-10 6:26 ` Tian, Kevin
2025-01-10 17:26 ` Jason Gunthorpe
2025-01-10 20:49 ` Nicolin Chen
2025-01-07 17:10 ` [PATCH v5 05/14] iommufd: Rename fault.c to eventq.c Nicolin Chen
2025-01-10 17:27 ` Jason Gunthorpe
2025-01-07 17:10 ` [PATCH v5 06/14] iommufd: Add IOMMUFD_OBJ_VEVENTQ and IOMMUFD_CMD_VEVENTQ_ALLOC Nicolin Chen
2025-01-10 7:06 ` Tian, Kevin
2025-01-10 21:29 ` Nicolin Chen
2025-01-13 2:52 ` Tian, Kevin
2025-01-13 4:51 ` Nicolin Chen
2025-01-13 8:17 ` Tian, Kevin
2025-01-13 19:10 ` Jason Gunthorpe
2025-01-10 17:48 ` Jason Gunthorpe
2025-01-10 19:27 ` Nicolin Chen
2025-01-10 19:49 ` Jason Gunthorpe
2025-01-10 21:58 ` Nicolin Chen
2025-01-13 19:12 ` Jason Gunthorpe
2025-01-13 19:18 ` Nicolin Chen [this message]
2025-01-07 17:10 ` [PATCH v5 07/14] iommufd/viommu: Add iommufd_viommu_get_vdev_id helper Nicolin Chen
2025-01-10 7:07 ` Tian, Kevin
2025-01-10 21:35 ` Nicolin Chen
2025-01-07 17:10 ` [PATCH v5 08/14] iommufd/viommu: Add iommufd_viommu_report_event helper Nicolin Chen
2025-01-10 7:12 ` Tian, Kevin
2025-01-10 14:51 ` Jason Gunthorpe
2025-01-10 18:40 ` Nicolin Chen
2025-01-10 17:41 ` Jason Gunthorpe
2025-01-10 18:38 ` Nicolin Chen
2025-01-10 19:51 ` Jason Gunthorpe
2025-01-10 19:56 ` Nicolin Chen
2025-01-13 5:37 ` Nicolin Chen
2025-01-13 19:21 ` Jason Gunthorpe
2025-01-13 19:47 ` Nicolin Chen
2025-01-13 19:54 ` Jason Gunthorpe
2025-01-13 20:44 ` Nicolin Chen
2025-01-14 13:41 ` Jason Gunthorpe
2025-01-17 22:11 ` Nicolin Chen
2025-01-20 18:18 ` Jason Gunthorpe
2025-01-20 20:52 ` Nicolin Chen
2025-01-21 18:36 ` Jason Gunthorpe
2025-01-21 19:55 ` Nicolin Chen
2025-01-21 20:09 ` Jason Gunthorpe
2025-01-21 21:02 ` Nicolin Chen
2025-01-21 21:14 ` Jason Gunthorpe
2025-01-21 21:40 ` Nicolin Chen
2025-01-22 0:21 ` Jason Gunthorpe
2025-01-22 7:15 ` Nicolin Chen
2025-01-22 9:33 ` Tian, Kevin
2025-01-22 19:54 ` Nicolin Chen
2025-01-23 13:42 ` Jason Gunthorpe
2025-01-22 8:05 ` Nicolin Chen
2025-01-22 18:02 ` Nicolin Chen
2025-01-23 7:02 ` Nicolin Chen
2025-01-23 13:43 ` Jason Gunthorpe
2025-01-07 17:10 ` [PATCH v5 09/14] iommufd/selftest: Require vdev_id when attaching to a nested domain Nicolin Chen
2025-01-07 17:10 ` [PATCH v5 10/14] iommufd/selftest: Add IOMMU_TEST_OP_TRIGGER_VEVENT for vEVENTQ coverage Nicolin Chen
2025-01-07 17:10 ` [PATCH v5 11/14] iommufd/selftest: Add IOMMU_VEVENTQ_ALLOC test coverage Nicolin Chen
2025-01-07 17:10 ` [PATCH v5 12/14] Documentation: userspace-api: iommufd: Update FAULT and VEVENTQ Nicolin Chen
2025-01-10 7:13 ` Tian, Kevin
2025-01-07 17:10 ` [PATCH v5 13/14] iommu/arm-smmu-v3: Introduce struct arm_smmu_vmaster Nicolin Chen
2025-01-13 19:29 ` Jason Gunthorpe
2025-01-13 19:52 ` Nicolin Chen
2025-01-07 17:10 ` [PATCH v5 14/14] iommu/arm-smmu-v3: Report events that belong to devices attached to vIOMMU Nicolin Chen
2025-01-09 11:04 ` kernel test robot
2025-01-13 19:01 ` Nicolin Chen
2025-01-13 19:06 ` Jason Gunthorpe
2025-01-13 19:15 ` Nicolin Chen
2025-01-13 19:18 ` Jason Gunthorpe
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