Re: [PATCH v8 05/14] KVM: Allow range-based TLB invalidation from common code

Raghavendra Rao Ananta
2023-08-09T16:42:08Z

On Tue, Aug 8, 2023 at 11:09 PM Gavin Shan <gshan@redhat.com> wrote:
>
> On 8/9/23 09:13, Raghavendra Rao Ananta wrote:
> > From: David Matlack <dmatlack@google.com>
> >
> > Make kvm_flush_remote_tlbs_range() visible in common code and create a
> > default implementation that just invalidates the whole TLB.
> >
> > This paves the way for several future features/cleanups:
> >
> > - Introduction of range-based TLBI on ARM.
> > - Eliminating kvm_arch_flush_remote_tlbs_memslot()
> > - Moving the KVM/x86 TDP MMU to common code.
> >
> > No functional change intended.
> >
> > Signed-off-by: David Matlack <dmatlack@google.com>
> > Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
> > Reviewed-by: Gavin Shan <gshan@redhat.com>
> > Reviewed-by: Shaoqin Huang <shahuang@redhat.com>
> > Reviewed-by: Anup Patel <anup@brainfault.org>
> > ---
> > arch/x86/include/asm/kvm_host.h | 2 ++
> > arch/x86/kvm/mmu/mmu.c | 8 ++++----
> > arch/x86/kvm/mmu/mmu_internal.h | 3 ---
> > include/linux/kvm_host.h | 12 ++++++++++++
> > virt/kvm/kvm_main.c | 13 +++++++++++++
> > 5 files changed, 31 insertions(+), 7 deletions(-)
> >
> > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> > index a2d3cfc2eb75c..b547d17c58f63 100644
> > --- a/arch/x86/include/asm/kvm_host.h
> > +++ b/arch/x86/include/asm/kvm_host.h
> > @@ -1804,6 +1804,8 @@ static inline int kvm_arch_flush_remote_tlbs(struct kvm *kvm)
> > return -ENOTSUPP;
> > }
> >
> > +#define __KVM_HAVE_ARCH_FLUSH_REMOTE_TLBS_RANGE
> > +
> > #define kvm_arch_pmi_in_guest(vcpu) \
> > ((vcpu) && (vcpu)->arch.handling_intr_from_guest)
> >
> > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> > index ec169f5c7dce2..6adbe6c870982 100644
> > --- a/arch/x86/kvm/mmu/mmu.c
> > +++ b/arch/x86/kvm/mmu/mmu.c
> > @@ -278,16 +278,16 @@ static inline bool kvm_available_flush_remote_tlbs_range(void)
> > return kvm_x86_ops.flush_remote_tlbs_range;
> > }
> >
> > -void kvm_flush_remote_tlbs_range(struct kvm *kvm, gfn_t start_gfn,
> > - gfn_t nr_pages)
> > +int kvm_arch_flush_remote_tlbs_range(struct kvm *kvm, gfn_t start_gfn,
> > + u64 nr_pages)
> > {
> > int ret = -EOPNOTSUPP;
> >
> > if (kvm_x86_ops.flush_remote_tlbs_range)
> > ret = static_call(kvm_x86_flush_remote_tlbs_range)(kvm, start_gfn,
> > nr_pages);
> > - if (ret)
> > - kvm_flush_remote_tlbs(kvm);
> > +
> > + return ret;
> > }
> >
>
> I guess @start_gfn can be renamed to @gfn, to be consistent with its declaration
> in include/linux/kvm_host.h and struct kvm_x86_ops::flush_remote_tlbs_range()
>
Oh, yes. I'll consider this change for v9 (if there are enough changes
and we plan to push one).

Thank you.
Raghavendra

> > static gfn_t kvm_mmu_page_get_gfn(struct kvm_mmu_page *sp, int index);
> > diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h
> > index d39af5639ce97..86cb83bb34804 100644
> > --- a/arch/x86/kvm/mmu/mmu_internal.h
> > +++ b/arch/x86/kvm/mmu/mmu_internal.h
> > @@ -170,9 +170,6 @@ bool kvm_mmu_slot_gfn_write_protect(struct kvm *kvm,
> > struct kvm_memory_slot *slot, u64 gfn,
> > int min_level);
> >
> > -void kvm_flush_remote_tlbs_range(struct kvm *kvm, gfn_t start_gfn,
> > - gfn_t nr_pages);
> > -
> > /* Flush the given page (huge or not) of guest memory. */
> > static inline void kvm_flush_remote_tlbs_gfn(struct kvm *kvm, gfn_t gfn, int level)
> > {
> > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> > index ade5d4500c2ce..f0be5d9c37dd1 100644
> > --- a/include/linux/kvm_host.h
> > +++ b/include/linux/kvm_host.h
> > @@ -1359,6 +1359,7 @@ int kvm_vcpu_yield_to(struct kvm_vcpu *target);
> > void kvm_vcpu_on_spin(struct kvm_vcpu *vcpu, bool yield_to_kernel_mode);
> >
> > void kvm_flush_remote_tlbs(struct kvm *kvm);
> > +void kvm_flush_remote_tlbs_range(struct kvm *kvm, gfn_t gfn, u64 nr_pages);
> >
> > #ifdef KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE
> > int kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int min);
> > @@ -1488,6 +1489,17 @@ static inline int kvm_arch_flush_remote_tlbs(struct kvm *kvm)
> > int kvm_arch_flush_remote_tlbs(struct kvm *kvm);
> > #endif
> >
> > +#ifndef __KVM_HAVE_ARCH_FLUSH_REMOTE_TLBS_RANGE
> > +static inline int kvm_arch_flush_remote_tlbs_range(struct kvm *kvm,
> > + gfn_t gfn, u64 nr_pages)
> > +{
> > + return -EOPNOTSUPP;
> > +}
> > +#else
> > +int kvm_arch_flush_remote_tlbs_range(struct kvm *kvm,
> > + gfn_t gfn, u64 nr_pages);
> > +#endif
> > +
> > #ifdef __KVM_HAVE_ARCH_NONCOHERENT_DMA
> > void kvm_arch_register_noncoherent_dma(struct kvm *kvm);
> > void kvm_arch_unregister_noncoherent_dma(struct kvm *kvm);
> > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> > index d6b0507861550..26e91000f579d 100644
> > --- a/virt/kvm/kvm_main.c
> > +++ b/virt/kvm/kvm_main.c
> > @@ -366,6 +366,19 @@ void kvm_flush_remote_tlbs(struct kvm *kvm)
> > }
> > EXPORT_SYMBOL_GPL(kvm_flush_remote_tlbs);
> >
> > +void kvm_flush_remote_tlbs_range(struct kvm *kvm, gfn_t gfn, u64 nr_pages)
> > +{
> > + if (!kvm_arch_flush_remote_tlbs_range(kvm, gfn, nr_pages))
> > + return;
> > +
> > + /*
> > + * Fall back to a flushing entire TLBs if the architecture range-based
> > + * TLB invalidation is unsupported or can't be performed for whatever
> > + * reason.
> > + */
> > + kvm_flush_remote_tlbs(kvm);
> > +}
> > +
> > static void kvm_flush_shadow_all(struct kvm *kvm)
> > {
> > kvm_arch_flush_shadow_all(kvm);
>
> Thanks,
> Gavin