Messages in this thread | | | Subject | Re: [PATCH] iommu: check for the deferred attach when attaching a device | From | Robin Murphy <> | Date | Tue, 12 Jan 2021 17:29:19 +0000 |
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On 2021-01-05 07:52, lijiang wrote: > 在 2021年01月05日 11:55, lijiang 写道: >> Hi, >> >> Also add Joerg to cc list. >> > > Also add more people to cc list, Jerry Snitselaar and Tom Lendacky. > > Thanks. > >> Thanks. >> Lianbo >> 在 2020年12月26日 13:39, Lianbo Jiang 写道: >>> Currently, because domain attach allows to be deferred from iommu >>> driver to device driver, and when iommu initializes, the devices >>> on the bus will be scanned and the default groups will be allocated. >>> >>> Due to the above changes, some devices could be added to the same >>> group as below: >>> >>> [ 3.859417] pci 0000:01:00.0: Adding to iommu group 16 >>> [ 3.864572] pci 0000:01:00.1: Adding to iommu group 16 >>> [ 3.869738] pci 0000:02:00.0: Adding to iommu group 17 >>> [ 3.874892] pci 0000:02:00.1: Adding to iommu group 17 >>> >>> But when attaching these devices, it doesn't allow that a group has >>> more than one device, otherwise it will return an error. This conflicts >>> with the deferred attaching. Unfortunately, it has two devices in the >>> same group for my side, for example: >>> >>> [ 9.627014] iommu_group_device_count(): device name[0]:0000:01:00.0 >>> [ 9.633545] iommu_group_device_count(): device name[1]:0000:01:00.1 >>> ... >>> [ 10.255609] iommu_group_device_count(): device name[0]:0000:02:00.0 >>> [ 10.262144] iommu_group_device_count(): device name[1]:0000:02:00.1 >>> >>> Finally, which caused the failure of tg3 driver when tg3 driver calls >>> the dma_alloc_coherent() to allocate coherent memory in the tg3_test_dma(). >>> >>> [ 9.660310] tg3 0000:01:00.0: DMA engine test failed, aborting >>> [ 9.754085] tg3: probe of 0000:01:00.0 failed with error -12 >>> [ 9.997512] tg3 0000:01:00.1: DMA engine test failed, aborting >>> [ 10.043053] tg3: probe of 0000:01:00.1 failed with error -12 >>> [ 10.288905] tg3 0000:02:00.0: DMA engine test failed, aborting >>> [ 10.334070] tg3: probe of 0000:02:00.0 failed with error -12 >>> [ 10.578303] tg3 0000:02:00.1: DMA engine test failed, aborting >>> [ 10.622629] tg3: probe of 0000:02:00.1 failed with error -12 >>> >>> In addition, the similar situations also occur in other drivers such >>> as the bnxt_en driver. That can be reproduced easily in kdump kernel >>> when SME is active. >>> >>> Add a check for the deferred attach in the iommu_attach_device() and >>> allow to attach the deferred device regardless of how many devices >>> are in a group.
Is this iommu_attach_device() call is coming from iommu-dma? (if not, then whoever's calling it probably shouldn't be)
Assuming so, then probably what should happen is to move the handling currently in iommu_dma_deferred_attach() into the core so that it can call __iommu_attach_device() directly - the intent is just to replay that exact call skipped in iommu_group_add_device(), so the legacy external iommu_attach_device() interface isn't really the right tool for the job anyway. That's just slightly awkward since ideally it wants to be done in a way that doesn't result in a redundant out-of-line call for !kdump.
Alternatively I suppose it *could* just call ops->attach_dev directly, but then we miss out on the tracepoint, and deferred attach is arguably one of the cases where that's most useful :/
Robin.
>>> >>> Signed-off-by: Lianbo Jiang <lijiang@redhat.com> >>> --- >>> drivers/iommu/iommu.c | 5 ++++- >>> 1 file changed, 4 insertions(+), 1 deletion(-) >>> >>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c >>> index ffeebda8d6de..dccab7b133fb 100644 >>> --- a/drivers/iommu/iommu.c >>> +++ b/drivers/iommu/iommu.c >>> @@ -1967,8 +1967,11 @@ int iommu_attach_device(struct iommu_domain *domain, struct device *dev) >>> */ >>> mutex_lock(&group->mutex); >>> ret = -EINVAL; >>> - if (iommu_group_device_count(group) != 1) >>> + if (!iommu_is_attach_deferred(domain, dev) && >>> + iommu_group_device_count(group) != 1) { >>> + dev_err_ratelimited(dev, "Group has more than one device\n"); >>> goto out_unlock; >>> + } >>> >>> ret = __iommu_attach_group(domain, group); >>> >>> > > _______________________________________________ > iommu mailing list > iommu@lists.linux-foundation.org > https://lists.linuxfoundation.org/mailman/listinfo/iommu >
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