Re: [PATCH v2 0/3][4.16] x86/IOMMU: enabled / intremap handling

[Ian Jackson <iwj@xxxxxxxxxxxxxx>]

Jan Beulich writes ("Re: [PATCH v2 0/3][4.16] x86/IOMMU: enabled / intremap 
handling"):
> On 02.11.2021 11:17, Jan Beulich wrote:
> > On 21.10.2021 11:57, Jan Beulich wrote:
> >> In the course of reading the response to v1 (patch 1 only) I realized
> >> that not only that patch needs further adjustment, but that also
> >> further changes are needed (and there's likely yet more amiss).
> >>
> >> 1: x86/IOMMU: mark IOMMU / intremap not in use when ACPI tables are missing
> >> 2: x86/APIC: avoid iommu_supports_x2apic() on error path
> >> 3: AMD/IOMMU: iommu_enable vs iommu_intremap
> > 
> > Ian, while we further discuss / refine patch 3, the first two have the
> > needed R-b, but will now need you release-ack aiui.
> 
> Seeing your reply on IRC, here an attempt at a release justification
> (the patches were ready by Oct 29, but no-one cared to commit them
> in my absence, so I thought I'd get away without such a write-up):
> 
> Patch 1 addresses a regression identified by Andrew. The main risk I
> see here (which has turned up only very recently) is disagreement on
> patch 3 which imo has an effect also on what patch 1 does, as to the
> (non-)effects of "iommu=off" on the hypervisor command line. This,
> however, is not an effect of the patch, but pre-existing behavior.
> The behavioral change (in this regard) is in patch 3, which is still
> under discussion.

Thank you.  I also went to the list and read the thread there.

Patch 1:

Reviewed-by: Ian Jackson <iwj@xxxxxxxxxxxxxx>

> Patch 2 corrects an (unlikely but not impossible to be taken) error
> path, supposedly making systems functional again in case they would
> in fact cause that error path to be taken. The risk looks low to me,
> given that two function calls with previously assumed to be
> identical results now get folded into one with the result latched.

This one also:

Release-Acked-by: Ian Jackson <iwj@xxxxxxxxxxxxxx>

I think, from reading the thread, that patch 3 is not targeting 4.16.

Thanks,
Ian.