Re: [PATCH v2 0/1] KVM: arm64: Map GPU memory with no struct pages

[Jason Gunthorpe <jgg@nvidia.com>]

On Tue, Dec 10, 2024 at 02:07:40PM +0000, Will Deacon wrote:
> On Mon, Nov 18, 2024 at 01:19:57PM +0000, ankita@nvidia.com wrote:
> > The changes are heavily influenced by the insightful discussions between
> > Catalin Marinas and Jason Gunthorpe [1] on v1. Many thanks for their
> > valuable suggestions.
> > 
> > Link: https://lore.kernel.org/lkml/20230907181459.18145-2-ankita@nvidia.com [1]
> 
> That's a different series, no? It got merged at v9:

I was confused by this too. v1 of that series included this patch, as
that series went along it became focused only on enabling WC
(Normal-NC) in a VM for device MMIO and this patch for device cachable
memory was dropped off.

There are two related things:
 1) Device MMIO memory should be able to be Normal-NC in a VM. Already
    merged
 2) Device Cachable memory (ie CXL and pre-CXL coherently attached
    memory) should be Normal Cachable in a VM, even if it doesn't have
    struct page/etc. (this patch)

IIRC this part was dropped off because of the MTE complexity that
Catalin raised.

Jason