Re: [PATCH 03/16] KVM: x86: set gfn-to-pfn cache length consistently with VM word size

[Paolo Bonzini]

On 11/14/22 15:53, Woodhouse, David wrote:
> Most other data structures, including the pvclock info (both Xen and
> native KVM), could potentially cross page boundaries. And isn't that
> also true for things that we'd want to use the GPC for in nesting?

Yes, for kvmclock we likely got away with it because Linux page-aligns 
it (and has been since 2013: commit ed55705dd, originally done for 
vsyscall support).  I have checked OpenBSD and FreeBSD and I think they 
do as well.

I am very very tempted to remove support for "old-style" kvmclock MSRs 
and retroactively declare new-style MSRs to accept only 32-byte aligned 
addresses.  However that doesn't solve the problem.

Paolo