linux-kernel - Re: [PATCH v2 2/3] drm/i915/gvt: switch from track_flush_slot to track_remove

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Message-ID: <Y26BV9a9q8nBz/+7@google.com>
Date:   Fri, 11 Nov 2022 17:07:35 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Yan Zhao <yan.y.zhao@...el.com>
Cc:     intel-gfx@...ts.freedesktop.org,
        intel-gvt-dev@...ts.freedesktop.org, zhenyuw@...ux.intel.com,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        pbonzini@...hat.com
Subject: Re: [PATCH v2 2/3] drm/i915/gvt: switch from track_flush_slot to
 track_remove_slot

On Fri, Nov 11, 2022, Yan Zhao wrote:
> KVMGT only cares about when a slot is indeed removed.
> So switch to use track_remove_slot which is called when a slot is removed.

This should capture the original motivation, i.e. that the existing
->track_flush_slot() hook is theoretically flawed.  I think it also makes sense
to call out that KVMGT undoubtedly does the wrong thing if a memslot is moved,
but that (a) KVMGT has never supported moving memslots and (b) there's no sane
use case for moving memslots that might be used by the guest for the GTT.

Bonus points if you can figure out a way to capture the restriction in the docs,
e.g. somewhere in gpu/i915.rst?

Lastly, provide a link to the original discussion which provides even more context.

Link: https://lore.kernel.org/all/20221108084416.11447-1-yan.y.zhao@intel.com

> Cc: Zhenyu Wang <zhenyuw@...ux.intel.com>
> Suggested-by: Sean Christopherson <seanjc@...gle.com>
> Signed-off-by: Yan Zhao <yan.y.zhao@...el.com>
> ---