On Tue, May 4, 2021 at 12:21 AM Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote: > > On 03/05/21 19:31, Ben Gardon wrote: > > On Mon, May 3, 2021 at 6:45 AM Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote: > >> > >> On 29/04/21 23:18, Ben Gardon wrote: > >>> This series enables KVM to save memory when using the TDP MMU by waiting > >>> to allocate memslot rmaps until they are needed. To do this, KVM tracks > >>> whether or not a shadow root has been allocated. In order to get away > >>> with not allocating the rmaps, KVM must also be sure to skip operations > >>> which iterate over the rmaps. If the TDP MMU is in use and we have not > >>> allocated a shadow root, these operations would essentially be op-ops > >>> anyway. Skipping the rmap operations has a secondary benefit of avoiding > >>> acquiring the MMU lock in write mode in many cases, substantially > >>> reducing MMU lock contention. > >>> > >>> This series was tested on an Intel Skylake machine. With the TDP MMU off > >>> and on, this introduced no new failures on kvm-unit-tests or KVM selftests. > >> > >> Thanks, I only reported some technicalities in the ordering of loads > >> (which matter since the loads happen with SRCU protection only). Apart > >> from this, this looks fine! > > > > Awesome to hear, thank you for the reviews. Should I send a v3 > > addressing those comments, or did you already make those changes when > > applying to your tree? > > No, I didn't (I wanted some oversight, and this is 5.14 stuff anyway). Ah, okay I'll send out a v3 soon, discussion on the other patches settles. > > Paolo >
