Hi, Jerry,
On Sat, Jun 25, 2022 at 03:13:33PM -0700, Jerry Snitselaar wrote:
> Subject: [PATCH] dmaengine: idxd: Only call idxd_enable_system_pasid if
> succeeded in enabling SVA feature
s/idxd_enable_system_pasid/idxd_enable_system_pasid()/
Please add your original error info in the commit message:
On a Sapphire Rapids system if you boot without intel_iommu=on, the IDXD
driver will crash during probe in iommu_sva_bind_device().
[ 21.423729] BUG: kernel NULL pointer dereference, address: 0000000000000038
[ 21.445108] #PF: supervisor read access in kernel mode
[ 21.450912] #PF: error_code(0x0000) - not-present page
[ 21.456706] PGD 0
[ 21.459047] Oops: 0000 [#1] PREEMPT SMP NOPTI
[ 21.464004] CPU: 0 PID: 1420 Comm: kworker/0:3 Not tainted 5.19.0-0.rc3.27.eln120.x86_64 #1
[ 21.464011] Hardware name: Intel Corporation EAGLESTREAM/EAGLESTREAM, BIOS EGSDCRB1.SYS.0067.D12.2110190954 10/19/2021
[ 21.464015] Workqueue: events work_for_cpu_fn
[ 21.464030] RIP: 0010:iommu_sva_bind_device+0x1d/0xe0
[ 21.464046] Code: c3 cc 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 41 57 41 56 49 89 d6 41 55 41 54 55 53 48 83 ec 08 48 8b 87 d8 02 00 00 <48> 8b 40 38 48 8b 50 10 48 83 7a 70 00 48 89 14 24 0f 84 91 00 00
[ 21.464050] RSP: 0018:ff7245d9096b7db8 EFLAGS: 00010296
[ 21.464054] RAX: 0000000000000000 RBX: ff1eadeec8a51000 RCX: 0000000000000000
[ 21.464058] RDX: ff7245d9096b7e24 RSI: 0000000000000000 RDI: ff1eadeec8a510d0
[ 21.464060] RBP: ff1eadeec8a51000 R08: ffffffffb1a12300 R09: ff1eadffbfce25b4
[ 21.464062] R10: ffffffffffffffff R11: 0000000000000038 R12: ffffffffc09f8000
[ 21.464065] R13: ff1eadeec8a510d0 R14: ff7245d9096b7e24 R15: ff1eaddf54429000
[ 21.464067] FS: 0000000000000000(0000) GS:ff1eadee7f600000(0000) knlGS:0000000000000000
[ 21.464070] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 21.464072] CR2: 0000000000000038 CR3: 00000008c0e10006 CR4: 0000000000771ef0
[ 21.464074] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 21.464076] DR3: 0000000000000000 DR6: 00000000fffe07f0 DR7: 0000000000000400
[ 21.464078] PKRU: 55555554
[ 21.464079] Call Trace:
[ 21.464083] <TASK>
[ 21.464092] idxd_pci_probe+0x259/0x1070 [idxd]
[ 21.464121] local_pci_probe+0x3e/0x80
[ 21.464132] work_for_cpu_fn+0x13/0x20
[ 21.464136] process_one_work+0x1c4/0x380
[ 21.464143] worker_thread+0x1ab/0x380
[ 21.464147] ? _raw_spin_lock_irqsave+0x23/0x50
[ 21.464158] ? process_one_work+0x380/0x380
[ 21.464161] kthread+0xe6/0x110
[ 21.464168] ? kthread_complete_and_exit+0x20/0x20
[ 21.464172] ret_from_fork+0x1f/0x30
> iommu_sva_bind_device requires that iommu_dev_enable_feature has been
> previously called with IOMMU_DEV_FEAT_SVA, and succeeded. Without this
> it is possible to run into a situation where you will dereference a
> null pointer if the intel_iommu driver is not enabled.
How about this commit message?
iommu_sva_bind_device() requires SVA has been enabled successfully on
the IDXD device before it's called. Otherwise, iommu_sva_bind_device()
will access a NULL pointer. If Intel IOMMU is disabled, SVA cannot be
enabled and thus idxd_enable_system_pasid() and iommu_sva_bind_device()
should not be called.
> Note: checkpatch didn't like the suggested addition of braces for the
> first arm of the "if (idxd_enable_system_pasid)" block.
Please see my comment in the code.
>
> Fixes: 42a1b73852c4 ("dmaengine: idxd: Separate user and kernel pasid enabling")
> Cc: Vinod Koul <vkoul@xxxxxxxxxx>
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Cc: Dave Jiang <dave.jiang@xxxxxxxxx>
> Cc: Fenghua Yu <fenghua.yu@xxxxxxxxx>
> Signed-off-by: Jerry Snitselaar <jsnitsel@xxxxxxxxxx>
Please add bug report link here:
Link: https://lore.kernel.org/dmaengine/20220623170232.6whonfjuh3m5vcoy@cantor/
> ---
> drivers/dma/idxd/init.c | 11 ++++++-----
> 1 file changed, 6 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/dma/idxd/init.c b/drivers/dma/idxd/init.c
> index 355fb3ef4cbf..5b49fd5c1e25 100644
> --- a/drivers/dma/idxd/init.c
> +++ b/drivers/dma/idxd/init.c
> @@ -514,13 +514,14 @@ static int idxd_probe(struct idxd_device *idxd)
> if (IS_ENABLED(CONFIG_INTEL_IDXD_SVM) && sva) {
> if (iommu_dev_enable_feature(dev, IOMMU_DEV_FEAT_SVA))
Need balanced braces in if-else.
Add "{" after this "if (...)".
> dev_warn(dev, "Unable to turn on user SVA feature.\n");
> - else
> + else {
Add "}" before this "else {".
> set_bit(IDXD_FLAG_USER_PASID_ENABLED, &idxd->flags);
>
> - if (idxd_enable_system_pasid(idxd))
> - dev_warn(dev, "No in-kernel DMA with PASID.\n");
> - else
> - set_bit(IDXD_FLAG_PASID_ENABLED, &idxd->flags);
> + if (idxd_enable_system_pasid(idxd))
> + dev_warn(dev, "No in-kernel DMA with PASID.\n");
> + else
> + set_bit(IDXD_FLAG_PASID_ENABLED, &idxd->flags);
> + }
> } else if (!sva) {
> dev_warn(dev, "User forced SVA off via module param.\n");
> }
> --
> 2.36.1
>
Thanks.
-Fenghua
