On Fri, 17 Feb 2023 04:21:28 +0000, Yu Zhao <yuzhao@xxxxxxxxxx> wrote: > > On Thu, Feb 16, 2023 at 9:12 PM Yu Zhao <yuzhao@xxxxxxxxxx> wrote: > > > > This patch adds kvm_arch_test_clear_young() for the vast majority of > > VMs that are not pKVM and run on hardware that sets the accessed bit > > in KVM page tables. I'm really interested in how you can back this statement. 90% of the HW I have access to is not FEAT_HWAFDB capable, either because it predates the feature or because the feature is too buggy to be useful. Do you have numbers? > > > > It relies on two techniques, RCU and cmpxchg, to safely test and clear > > the accessed bit without taking the MMU lock. The former protects KVM > > page tables from being freed while the latter clears the accessed bit > > atomically against both the hardware and other software page table > > walkers. > > > > Signed-off-by: Yu Zhao <yuzhao@xxxxxxxxxx> > > --- > > arch/arm64/include/asm/kvm_host.h | 7 +++ > > arch/arm64/include/asm/kvm_pgtable.h | 8 +++ > > arch/arm64/include/asm/stage2_pgtable.h | 43 ++++++++++++++ > > arch/arm64/kvm/arm.c | 1 + > > arch/arm64/kvm/hyp/pgtable.c | 51 ++-------------- > > arch/arm64/kvm/mmu.c | 77 ++++++++++++++++++++++++- > > 6 files changed, 141 insertions(+), 46 deletions(-) > > Adding Marc and Will. > > Can you please add other interested parties that I've missed? The MAINTAINERS file has it all: KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64) M: Marc Zyngier <maz@xxxxxxxxxx> M: Oliver Upton <oliver.upton@xxxxxxxxx> R: James Morse <james.morse@xxxxxxx> R: Suzuki K Poulose <suzuki.poulose@xxxxxxx> R: Zenghui Yu <yuzenghui@xxxxxxxxxx> L: kvmarm@xxxxxxxxxxxxxxx May I suggest that you repost your patch and Cc the interested parties yourself? I guess most folks will want to see this in context, and not as a random, isolated change with no rationale. M. -- Without deviation from the norm, progress is not possible.
