Re: [PATCH v4 09/13] iommu/arm-smmu-v3: Implement set_dev_pasid

[Michael Shavit]

> Would you please elaborate a bit more for the use case of
allowing that?

In short; to support devices that use SSID to isolate different
(device) contexts. Those contexts (and the memory available to them)
is partially managed by the device's Kernel driver.

> And which test configuration do you cover
using smmute? Would you mind sharing your test commands?

I used the setup suggested by Jean in
https://lore.kernel.org/all/20230511195928.GA288490@myrica/ , with the
following commands:
>>>
# Basic test
./smmute;
./smmute -u mmap;

# Test invalid access to not-mapped address
./smmute -u mmap -f drv;

# Test invalid access after unmap
./smmute -u mmap -f write -d;

# Check smmu_mn released when killed
mount -t tracefs nodev /sys/kernel/tracing;
echo 1 > /sys/kernel/tracing/events/iommu/enable;
echo 1 > /sys/kernel/tracing/events/smmu/enable;
./smmute -u mmap -k bind;
cat /sys/kernel/tracing/trace;
<<<

This only covers existing SVA functionality. To test the functionality
introduced by this patch, I used a device capable of generating DMA
transactions w/ SSID and a test driver with following tests:
1. Successful dma Read/Write to buffer mapped on domain attached with pasid
2. Unsuccessful dma Read/Write to same buffer after domain detached
from pasid, or after buffer unmapped from domain
3. Variations of the above with a domain attached to multiple pasids

I've been considering migrating those tests to the smmute driver if
that would be valuable.



On Fri, Jun 23, 2023 at 8:32 AM Nicolin Chen <nicolinc@xxxxxxxxxx> wrote:
>
> Hi Michael,
>
> On Wed, Jun 21, 2023 at 02:37:21PM +0800, Michael Shavit wrote:
> >
> > This change enables the use of the iommu_attach_dev_pasid API for
> > UNMANAGED domains. The primary use-case is to allow in-kernel users of
> > the iommu API to manage domains with PASID. This change also allows for
> > future support of pasid in the DMA api.
>
> Would you please elaborate a bit more for the use case of
> allowing that? And which test configuration do you cover
> using smmute? Would you mind sharing your test commands?
>
> I have run a sanity with this series using an SVA domain
> with a real master. It seems to be fine.
>
> Thanks
> Nicolin