Re: [PATCH] iommu/vt-d: Fix wrong analysis whether devices share the same bus

[Logan Gunthorpe]

On 2019-08-20 2:53 a.m., Nadav Amit wrote:
> set_msi_sid_cb() is used to determine whether device aliases share the
> same bus, but it can provide false indications that aliases use the same
> bus when in fact they do not. The reason is that set_msi_sid_cb()
> assumes that pdev is fixed, while actually pci_for_each_dma_alias() can
> call fn() when pdev is set to a subordinate device.
> 
> As a result, running an VM on ESX with VT-d emulation enabled can
> results in the log warning such as:
> 
>   DMAR: [INTR-REMAP] Request device [00:11.0] fault index 3b [fault reason 38] Blocked an interrupt request due to source-id verification failure
> 
> This seems to cause additional ata errors such as:
>   ata3.00: qc timeout (cmd 0xa1)
>   ata3.00: failed to IDENTIFY (I/O error, err_mask=0x4)
> 
> These timeouts also cause boot to be much longer and other errors.
> 
> Fix it by checking comparing the alias with the previous one instead.
> 
> Fixes: 3f0c625c6ae71 ("iommu/vt-d: Allow interrupts from the entire bus for aliased devices")
> Cc: stable@xxxxxxxxxxxxxxx
> Cc: Logan Gunthorpe <logang@xxxxxxxxxxxx>
> Cc: David Woodhouse <dwmw2@xxxxxxxxxxxxx>
> Cc: Joerg Roedel <joro@xxxxxxxxxx>
> Cc: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
> Signed-off-by: Nadav Amit <namit@xxxxxxxxxx>

This looks good to me.

Reviewed-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>

Thanks!

Logan