On 01.02.23 20:45, Mathias Krause wrote: > v2: https://lore.kernel.org/kvm/20230118145030.40845-1-minipli@xxxxxxxxxxxxxx/ > > This series is a resurrection of the missing pieces of Paolo's previous > attempt[1] to avoid needless MMU roots unloading. The performance gap > between TDP and legacy MMU is still existent, especially noticeable under > grsecurity which implements kernel W^X by toggling CR0.WP, which happens > very frequently. > > Patches 1-13 and 17 of the old series had been merged, but, unfortunately, > the remaining parts never saw a v3. I therefore took care of these, took > Sean's feedback into account[2] and simplified the whole approach to just > handle the case we care most about explicitly. > > Patch 1 is a v3 of [3], addressing Sean's feedback. > > Patch 2 is specifically useful for grsecurity, as handle_cr() is by far > *the* top vmexit reason. > > Patch 3 is the most important one, as it skips unloading the MMU roots for > CR0.WP toggling. > > Sean was suggesting another change on top of v2 of this series, to skip > intercepting CR0.WP writes completely for VMX[4]. That turned out to be > yet another performance boost and is implemenmted in patch 6. > > While patches 1 and 2 bring small performance improvements already, the > big gains come from patches 3 and 6. > > I used 'ssdd 10 50000' from rt-tests[5] as a micro-benchmark, running on a > grsecurity L1 VM. Below table shows the results (runtime in seconds, lower > is better): > > legacy TDP shadow > kvm.git/queue 11.55s 13.91s 75.2s > + patches 1-3 7.32s 7.31s 74.6s > + patches 4-6 4.89s 4.89s 73.4s > > This series builds on top of kvm.git/queue, namely commit de60733246ff > ("Merge branch 'kvm-hw-enable-refactor' into HEAD"). > > Patches 1-3 didn't change from v2, beside minor changlog mangling. > > Patches 4-6 are new to v3. > > Thanks, > Mathias > > [1] https://lore.kernel.org/kvm/20220217210340.312449-1-pbonzini@xxxxxxxxxx/ > [2] https://lore.kernel.org/kvm/YhATewkkO%2Fl4P9UN@xxxxxxxxxx/ > [3] https://lore.kernel.org/kvm/YhAB1d1%2FnQbx6yvk@xxxxxxxxxx/ > [4] https://lore.kernel.org/kvm/Y8cTMnyBzNdO5dY3@xxxxxxxxxx/ > [5] https://git.kernel.org/pub/scm/utils/rt-tests/rt-tests.git > > Mathias Krause (5): > KVM: VMX: Avoid retpoline call for control register caused exits > KVM: x86: Do not unload MMU roots when only toggling CR0.WP > KVM: x86: Make use of kvm_read_cr*_bits() when testing bits > KVM: x86/mmu: Fix comment typo > KVM: VMX: Make CR0.WP a guest owned bit > > Paolo Bonzini (1): > KVM: x86/mmu: Avoid indirect call for get_cr3 > > arch/x86/kvm/kvm_cache_regs.h | 3 ++- > arch/x86/kvm/mmu/mmu.c | 31 ++++++++++++++++++++----------- > arch/x86/kvm/mmu/paging_tmpl.h | 2 +- > arch/x86/kvm/mmu/spte.c | 2 +- > arch/x86/kvm/pmu.c | 4 ++-- > arch/x86/kvm/vmx/capabilities.h | 1 + > arch/x86/kvm/vmx/nested.c | 4 ++-- > arch/x86/kvm/vmx/vmx.c | 15 ++++++++++++--- > arch/x86/kvm/vmx/vmx.h | 8 ++++++++ > arch/x86/kvm/x86.c | 9 +++++++++ > 10 files changed, 58 insertions(+), 21 deletions(-) Ping! Anything I can do to help getting this series reviewed and hopefully merged? Thanks, Mathias
