Re: [PATCH v4 5/6] KVM: MMU: combine guest pte read between walk and pte prefetch

Marcelo Tosatti
2010-07-02T17:22:45Z

On Thu, Jul 01, 2010 at 09:55:56PM +0800, Xiao Guangrong wrote:
> Combine guest pte read between guest pte walk and pte prefetch
>
> Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
> ---
> arch/x86/kvm/paging_tmpl.h | 48 ++++++++++++++++++++++++++++++-------------
> 1 files changed, 33 insertions(+), 15 deletions(-)

Can't do this, it can miss invlpg:

vcpu0 vcpu1
read guest ptes
modify guest pte
invlpg
instantiate stale
guest pte

See how the pte is reread inside fetch with mmu_lock held.

Otherwise the patchset looks fine to me.