Re: [PATCH] iommu/vt-d fix adding non-PCI devices to Intel IOMMU

From: Lu Baolu <baolu.lu@linux.intel.com>
To: Patrick Steinhardt <ps@pks.im>, iommu@lists.linux-foundation.org
Cc: David Woodhouse <dwmw2@infradead.org>
Subject: Re: [PATCH] iommu/vt-d fix adding non-PCI devices to Intel IOMMU
Date: Mon, 30 Dec 2019 08:35:11 +0800	[thread overview]
Message-ID: <4a0cb002-bd41-b1df-5b63-16ea6f50f406@linux.intel.com> (raw)
In-Reply-To: <b47f83548d855ac920ad06b0ff78b877fa4f5189.1577404477.git.ps@pks.im>

Hi,

On 12/27/19 7:56 AM, Patrick Steinhardt wrote:
> Starting with commit fa212a97f3a3 ("iommu/vt-d: Probe DMA-capable ACPI
> name space devices"), we now probe DMA-capable ACPI name
> space devices. On Dell XPS 13 9343, which has an Intel LPSS platform
> device INTL9C60 enumerated via ACPI, this change leads to the following
> warning:
> 
>      ------------[ cut here ]------------
>      WARNING: CPU: 1 PID: 1 at pci_device_group+0x11a/0x130
>      CPU: 1 PID: 1 Comm: swapper/0 Tainted: G                T 5.5.0-rc3+ #22
>      Hardware name: Dell Inc. XPS 13 9343/0310JH, BIOS A20 06/06/2019
>      RIP: 0010:pci_device_group+0x11a/0x130
>      Code: f0 ff ff 48 85 c0 49 89 c4 75 c4 48 8d 74 24 10 48 89 ef e8 48 ef ff ff 48 85 c0 49 89 c4 75 af e8 db f7 ff ff 49 89 c4 eb a5 <0f> 0b 49 c7 c4 ea ff ff ff eb 9a e8 96 1e c7 ff 66 0f 1f 44 00 00
>      RSP: 0000:ffffc0d6c0043cb0 EFLAGS: 00010202
>      RAX: 0000000000000000 RBX: ffffa3d1d43dd810 RCX: 0000000000000000
>      RDX: ffffa3d1d4fecf80 RSI: ffffa3d12943dcc0 RDI: ffffa3d1d43dd810
>      RBP: ffffa3d1d43dd810 R08: 0000000000000000 R09: ffffa3d1d4c04a80
>      R10: ffffa3d1d4c00880 R11: ffffa3d1d44ba000 R12: 0000000000000000
>      R13: ffffa3d1d4383b80 R14: ffffa3d1d4c090d0 R15: ffffa3d1d4324530
>      FS:  0000000000000000(0000) GS:ffffa3d1d6700000(0000) knlGS:0000000000000000
>      CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>      CR2: 0000000000000000 CR3: 000000000460a001 CR4: 00000000003606e0
>      Call Trace:
>       ? iommu_group_get_for_dev+0x81/0x1f0
>       ? intel_iommu_add_device+0x61/0x170
>       ? iommu_probe_device+0x43/0xd0
>       ? intel_iommu_init+0x1fa2/0x2235
>       ? pci_iommu_init+0x52/0xe7
>       ? e820__memblock_setup+0x15c/0x15c
>       ? do_one_initcall+0xcc/0x27e
>       ? kernel_init_freeable+0x169/0x259
>       ? rest_init+0x95/0x95
>       ? kernel_init+0x5/0xeb
>       ? ret_from_fork+0x35/0x40
>      ---[ end trace 28473e7abc25b92c ]---
>      DMAR: ACPI name space devices didn't probe correctly
> 
> The bug results from the fact that while we now enumerate ACPI devices,
> we aren't able to handle any non-PCI device when generating the device
> group. Fix the issue by implementing an Intel-specific callback that
> returns `pci_device_group` only if the device is a PCI device.
> Otherwise, it will return a generic device group.
> 
> Fixes: fa212a97f3a3 ("iommu/vt-d: Probe DMA-capable ACPI name space devices")
> Signed-off-by: Patrick Steinhardt<ps@pks.im>

This will allocate per-device group for the ANDD device. Different
devices that couldn't be isolated should be put in a single group.
Unfortunately, the spec doesn't state how the ANDD devices are isolated.

Currently we don't support assigning a platform device to user level as
far as I can see, so though this fix is not the best, it won't break
anything. I will ack this fix so that the kernel crash could be fixed
before we figure out a better solution.

Cc: stable@vger.kernel.org # v5.3+
Acked-by: Lu Baolu <baolu.lu@linux.intel.com>

Best regards,
-baolu
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