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Peter Anvin" , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Shaoqin Huang , Gavin Shan , Ricardo Koller , Raghavendra Rao Ananta , Ryan Roberts , David Rientjes , Axel Rasmussen , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Stat-Signature: uuhysdnh1439k9ua8nsrta8464zti88y X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: B071D4000F X-HE-Tag: 1712858883-438028 X-HE-Meta: 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 kJ+ojtpK eo3R+N/0BOxWJVNu0rfexoNdGviAc3B0X2R3wdu+E5E1rLyqI5zh1S8KSlhjbrP/FsKWTVaz75tgSuKIuLrqBdNaOchzAhCtpxOubCMUvKbLTWhrCAfOtEariSc4dErcRnBNVVFmm+KxTi8t+sWRCwJIcGWdWWGmYQ8jLZCrm1O8dG3yxoaDbYxsgfUH5yyVXXGRLkMLaL3SkCQv2OZ9Ijh+97PeWIJ9dlFM8ciyF/mxU5KTViwkSoTjKnwtYUBcFkXAJDnB0Pvql19NC07c+p1Zm9MvF1tdlJiwk X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Apr 11, 2024 at 11:00=E2=80=AFAM David Matlack wrote: > > On Thu, Apr 11, 2024 at 10:28=E2=80=AFAM David Matlack wrote: > > > > On 2024-04-11 10:08 AM, David Matlack wrote: > > > On 2024-04-01 11:29 PM, James Houghton wrote: > > > > Only handle the TDP MMU case for now. In other cases, if a bitmap w= as > > > > not provided, fallback to the slowpath that takes mmu_lock, or, if = a > > > > bitmap was provided, inform the caller that the bitmap is unreliabl= e. > > > > > > > > Suggested-by: Yu Zhao > > > > Signed-off-by: James Houghton > > > > --- > > > > arch/x86/include/asm/kvm_host.h | 14 ++++++++++++++ > > > > arch/x86/kvm/mmu/mmu.c | 16 ++++++++++++++-- > > > > arch/x86/kvm/mmu/tdp_mmu.c | 10 +++++++++- > > > > 3 files changed, 37 insertions(+), 3 deletions(-) > > > > > > > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm= /kvm_host.h > > > > index 3b58e2306621..c30918d0887e 100644 > > > > --- a/arch/x86/include/asm/kvm_host.h > > > > +++ b/arch/x86/include/asm/kvm_host.h > > > > @@ -2324,4 +2324,18 @@ int memslot_rmap_alloc(struct kvm_memory_slo= t *slot, unsigned long npages); > > > > */ > > > > #define KVM_EXIT_HYPERCALL_MBZ GENMASK_ULL(31, 1) > > > > > > > > +#define kvm_arch_prepare_bitmap_age kvm_arch_prepare_bitmap_age > > > > +static inline bool kvm_arch_prepare_bitmap_age(struct mmu_notifier= *mn) > > > > +{ > > > > + /* > > > > + * Indicate that we support bitmap-based aging when using the T= DP MMU > > > > + * and the accessed bit is available in the TDP page tables. > > > > + * > > > > + * We have no other preparatory work to do here, so we do not n= eed to > > > > + * redefine kvm_arch_finish_bitmap_age(). > > > > + */ > > > > + return IS_ENABLED(CONFIG_X86_64) && tdp_mmu_enabled > > > > + && shadow_accessed_mask; > > > > +} > > > > + > > > > #endif /* _ASM_X86_KVM_HOST_H */ > > > > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > > > > index 992e651540e8..fae1a75750bb 100644 > > > > --- a/arch/x86/kvm/mmu/mmu.c > > > > +++ b/arch/x86/kvm/mmu/mmu.c > > > > @@ -1674,8 +1674,14 @@ bool kvm_age_gfn(struct kvm *kvm, struct kvm= _gfn_range *range) > > > > { > > > > bool young =3D false; > > > > > > > > - if (kvm_memslots_have_rmaps(kvm)) > > > > + if (kvm_memslots_have_rmaps(kvm)) { > > > > + if (range->lockless) { > > > > + kvm_age_set_unreliable(range); > > > > + return false; > > > > + } > > > > > > If a VM has TDP MMU enabled, supports A/D bits, and is using nested > > > virtualization, MGLRU will effectively be blind to all accesses made = by > > > the VM. > > > > > > kvm_arch_prepare_bitmap_age() will return true indicating that the > > > bitmap is supported. But then kvm_age_gfn() and kvm_test_age_gfn() wi= ll > > > return false immediately and indicate the bitmap is unreliable becaus= e a > > > shadow root is allocate. The notfier will then return > > > MMU_NOTIFIER_YOUNG_BITMAP_UNRELIABLE. > > Ah no, I'm wrong here. Setting args.unreliable causes the notifier to > return 0 instead of MMU_NOTIFIER_YOUNG_FAST. > MMU_NOTIFIER_YOUNG_BITMAP_UNRELIABLE is used for something else. Nope, wrong again. Just ignore me while I try to figure out how this actually works :)