On Tue, Mar 15, 2022 at 12:40 AM Peter Xu <peterx@xxxxxxxxxx> wrote: > > On Fri, Mar 11, 2022 at 12:25:03AM +0000, David Matlack wrote: > > Commit fb58a9c345f6 ("KVM: x86/mmu: Optimize MMU page cache lookup for > > fully direct MMUs") skipped the unsync checks and write flood clearing > > for full direct MMUs. We can extend this further and skip the checks for > > all direct shadow pages. Direct shadow pages are never marked unsynced > > or have a non-zero write-flooding count. > > Nit: IMHO it's better to spell out the exact functional change, IIUC those > are the direct mapped SPs where guest uses huge pages but host uses only > small pages for the shadowing? Yes that's correct. I'll include that in the commit message in the next version. > > > > > Checking sp->role.direct alos generates better code than checking > > direct_map because, due to register pressure, direct_map has to get > > shoved onto the stack and then pulled back off. > > > > No functional change intended. > > > > Reviewed-by: Sean Christopherson <seanjc@xxxxxxxxxx> > > Signed-off-by: David Matlack <dmatlack@xxxxxxxxxx> > > Reviewed-by: Peter Xu <peterx@xxxxxxxxxx> > > -- > Peter Xu >