On Thu, Apr 13, 2023 at 04:12:51PM -0700, Sean Christopherson wrote: > Preserve TDP MMU roots until they are explicitly invalidated by gifting > the TDP MMU itself a reference to a root when it is allocated. Keeping a > reference in the TDP MMU fixes a flaw where the TDP MMU exhibits terrible > performance, and can potentially even soft-hang a vCPU, if a vCPU > frequently unloads its roots, e.g. when KVM is emulating SMI+RSM. > [...] > > Reported-by: Jeremi Piotrowski <jpiotrowski@xxxxxxxxxxxxxxxxxxx> > Link: https://lore.kernel.org/all/959c5bce-beb5-b463-7158-33fc4a4f910c@xxxxxxxxxxxxxxxxxxx > Link: https://lkml.kernel.org/r/20220209170020.1775368-1-pbonzini%40redhat.com > Link: https://lore.kernel.org/all/20230322013731.102955-1-minipli@xxxxxxxxxxxxxx > Cc: David Matlack <dmatlack@xxxxxxxxxx> > Cc: Ben Gardon <bgardon@xxxxxxxxxx> > Cc: stable@xxxxxxxxxxxxxxx > Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx> Reviewed-by: David Matlack <dmatlack@xxxxxxxxxx>
