On Wed, 2022-10-12 at 18:16 +0000, Sean Christopherson wrote: > From: David Matlack <dmatlack@xxxxxxxxxx> > > Change tdp_mmu to a read-only parameter and drop the per-vm > tdp_mmu_enabled. Keep the is_tdp_mmu_enabled() helper instead of > referencing tdp_mmu_enabled directly to allow for future optimizations > without needing to churn a lot of code, e.g. KVM can use a static key > for now that the knob is read-only after the vendor module is loaded. > > The TDP MMU was introduced in 5.10 and has been enabled by default since > 5.15. At this point there are no known functionality gaps between the > TDP MMU and the shadow MMU, and the TDP MMU uses less memory and scales > better with the number of vCPUs. In other words, there is no good reason > to disable the TDP MMU on a live system. > > Purposely do not drop tdp_mmu=N support (i.e. do not force 64-bit KVM to > always use the TDP MMU) since tdp_mmu=N is still used to get test > coverage of KVM's shadow MMU TDP support, which is used in 32-bit KVM. > > Signed-off-by: David Matlack <dmatlack@xxxxxxxxxx> > [sean: keep is_tdp_mmu_enabled()] > Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx> Reviewed-by: Kai Huang <kai.huang@xxxxxxxxx>
