Re: [PATCH v6 16/17] RFC: kvm: pass kvm argument to follow_pfn callsites

On Fri, Nov 20, 2020 at 4:33 PM Paolo Bonzini [off-list ref] wrote:

On 19/11/20 15:41, Daniel Vetter wrote:

quoted

Both Christoph Hellwig and Jason Gunthorpe suggested that usage of
follow_pfn by modules should be locked down more. To do so callers
need to be able to pass the mmu_notifier subscription corresponding
to the mm_struct to follow_pfn().

This patch does the rote work of doing that in the kvm subsystem. In
most places this is solved by passing struct kvm * down the call
stacks as an additional parameter, since that contains the
mmu_notifier.

Compile tested on all affected arch.

It's a bit of a pity, it's making an API more complex (the point of
gfn_to_pfn_memslot vs gfn_to_pfn is exactly that you don't need a
"struct kvm*" and it's clear that you've already done the lookup into
that struct kvm.

Yeah I noticed that, I think pushing the lookups down should work, but
that's a fairly large-scale change. I didn't want to do that for the
RFC since it would distract from the actual change/goal.
-Daniel

But it's not a big deal, and the rationale at least makes sense.  So,

Acked-by: Paolo Bonzini <pbonzini@redhat.com>

Paolo

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

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