Re: Cache Invalidation Solution for Nested IOMMU

[Nicolin Chen <nicolinc@nvidia.com>]

Hi Zhangfei,

On Wed, Apr 12, 2023 at 10:47:56AM +0800, Zhangfei Gao wrote:

> qemu-system-aarch64: IOMMU_HWPT_INVALIDATE failed: No such device

Only ATC_INV checks vSID field and return -ENODEV if vSID is
not linked to any pSID (i.e. set_rid_user has not been called
correctly for that device.)

Maybe you can try some prints in set_rid_user on both kernel
and qemu sides.
 
> host:
> [218.986319] arm-smmu-v3 arm-smmu-v3.3.auto: unexpected global error
> reported (0x00000001), this could be serious
> [218.996464] arm-smmu-v3 arm-smmu-v3.3.auto: CMDQ error (cons
> 0x01004805): Illegal command
> [219.004606] arm-smmu-v3 arm-smmu-v3.3.auto: skipping command in error state:
> [219.011622] arm-smmu-v3 arm-smmu-v3.3.auto:0x0060000202110687
> [219.017515] arm-smmu-v3 arm-smmu-v3.3.auto:0x0000000000000000
> [219.023422] arm-smmu-v3 arm-smmu-v3.3.auto: unexpected global error
> reported (0x00000001), this could be serious
> [219.033550] arm-smmu-v3 arm-smmu-v3.3.auto: CMDQ error (cons
> 0x01004806): Illegal command
> [219.041692] arm-smmu-v3 arm-smmu-v3.3.auto: skipping command in error state:
> [219.048707] arm-smmu-v3 arm-smmu-v3.3.auto:0x0000000000000000
> [219.054600]arm-smmu-v3 arm-smmu-v3.3.auto:0x0000000000000000

This two commands look very wrong...wondering why host could
encounter them.

There's a pr_debug in arm_smmu_fix_user_cmd() that can change
to pr_alert for guest queue debugging.

Sorry, the mmap solution might be buggy, as it's a proof of
concept.

Thanks
Nicolin