Re: [PATCH v9 08/12] iommu/arm-smmu-v3-kdump: Reserve crashed kernel's ASIDs and VMIDs

[Jason Gunthorpe]

> Nested STE's guest-owned CD table is in IPA space and left alone: its ASIDs
> only pair with the nonzero S2VMID being reserved, so they cannot alias this
> kernel's VMID-0 or EL2 stage-1 domains.

This explanation is a bit off.. Nested ASIDs have a unique ASID space under
their VMID. SO long as the VMID is reserved there is no reason to inspect the
(VMID,ASID) list.

The only ASIDs we need to load are ones in the namespace the new kernel will
use itself, which you explained here:

> Note that, on an E2H/VHE host, the kernel's stage-1 domains are tagged by
> the EL2 ASID, and the TLBI_EL2_* commands take no VMID. So isolating this
> kernel by a reserved VMID alone would not work. Reserving the ASIDs covers
> both the E2H and the NSEL1 cases.

That is a nice observation and it would have been really cool if this kernel
could just use a unique VMID and not have to worry about ASID. Oh wel.

Seems fine otherwise

Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>

-- 
Jason