Re: [PATCH v8 13/46] KVM: guest_memfd: Add base support for KVM_SET_MEMORY_ATTRIBUTES2

[Sean Christopherson]

On Fri, Jun 19, 2026, Fuad Tabba wrote:
> On Fri, 19 Jun 2026 at 01:31, Ackerley Tng via B4 Relay
> <devnull+ackerleytng.google.com@xxxxxxxxxx> wrote:
> >
> > From: Ackerley Tng <ackerleytng@xxxxxxxxxx>
> >
> > Introduce base support for KVM_SET_MEMORY_ATTRIBUTES2 in guest_memfd, which
> > just updates attributes tracked by guest_memfd.
> >
> > Validate input fields in general. Guard usage of KVM_SET_MEMORY_ATTRIBUTES2
> > by making sure requested attributes are supported for this instance of kvm.
> >
> > A new KVM_SET_MEMORY_ATTRIBUTES2 is defined to support writes (unlike
> > KVM_SET_MEMORY_ATTRIBUTES) in addition to reads so it can provide error
> > details to userspace. This will be used in a later patch.
> >
> > The two ioctls use their corresponding structs with no overlap, but
> > backward compatibility is baked in for future support of
> > KVM_SET_MEMORY_ATTRIBUTES2 and struct kvm_memory_attributes2 in the VM
> > ioctl.
> >
> > The process of setting memory attributes is set up such that the later half
> > will not fail due to allocation. Any necessary checks are performed before
> > the point of no return.
> >
> > Co-developed-by: Vishal Annapurve <vannapurve@xxxxxxxxxx>
> > Signed-off-by: Vishal Annapurve <vannapurve@xxxxxxxxxx>
> > Co-developed-by: Sean Christoperson <seanjc@xxxxxxxxxx>
> > Signed-off-by: Sean Christoperson <seanjc@xxxxxxxxxx>
> > Reviewed-by: Fuad Tabba <tabba@xxxxxxxxxx>
> > Signed-off-by: Ackerley Tng <ackerleytng@xxxxxxxxxx>
> 
> Note sure if it's user error on my part, if I'm applying this to the
> wrong base, but I found a build break here on patch 13:
> kvm_gmem_invalidate_start() doesn't exist in the base tree. The
> function is kvm_gmem_invalidate_begin() here. The rename
> (190cc5370a8b6) landed via a different merge path and isn't an
> ancestor of the stated base.
> 
> Patches 19 and 20 have the same mismatch. Fix for all three is
> s/kvm_gmem_invalidate_start/kvm_gmem_invalidate_begin/.

Ya, Ackerley used a slightly older kvm/next to send the patches.  I at least was
testing against kvm-x86/next, which does have the rename.

Other than noting that this should be applied against the current kvm/next, I
don't think there's anything else to be done?