Re: [PATCH v6 03/11] KVM: Allow range-based TLB invalidation from common code

[Raghavendra Rao Ananta]

On Mon, Jul 17, 2023 at 4:40 AM Shaoqin Huang <shahuang@xxxxxxxxxx> wrote:
>
>
>
> On 7/15/23 08:53, Raghavendra Rao Ananta wrote:
> > From: David Matlack <dmatlack@xxxxxxxxxx>
> >
> > 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@xxxxxxxxxx>
> > Signed-off-by: Raghavendra Rao Ananta <rananta@xxxxxxxxxx>
> > Reviewed-by: Gavin Shan <gshan@xxxxxxxxxx>
> > ---
> >   arch/x86/include/asm/kvm_host.h |  3 +++
> >   arch/x86/kvm/mmu/mmu.c          |  9 ++++-----
> >   arch/x86/kvm/mmu/mmu_internal.h |  3 ---
> >   include/linux/kvm_host.h        |  9 +++++++++
> >   virt/kvm/kvm_main.c             | 13 +++++++++++++
> >   5 files changed, 29 insertions(+), 8 deletions(-)
> >
> > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> > index a2d3cfc2eb75..08900afbf2ad 100644
> > --- a/arch/x86/include/asm/kvm_host.h
> > +++ b/arch/x86/include/asm/kvm_host.h
> > @@ -1804,6 +1804,9 @@ static inline int kvm_arch_flush_remote_tlbs(struct kvm *kvm)
> >               return -ENOTSUPP;
> >   }
> >
> > +#define __KVM_HAVE_ARCH_FLUSH_REMOTE_TLBS_RANGE
> > +int kvm_arch_flush_remote_tlbs_range(struct kvm *kvm, gfn_t start_gfn, u64 pages);
> > +
> >   #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 ec169f5c7dce..aaa5e336703a 100644
> > --- a/arch/x86/kvm/mmu/mmu.c
> > +++ b/arch/x86/kvm/mmu/mmu.c
> > @@ -278,16 +278,15 @@ 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 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);
> > +                                                                     pages);
> This will be good if parameter pages aligned with parameter kvm.
>
Agreed, but pulling 'pages' above brings the char count to 83. If
that's acceptable, I'm happy to do it in v7.

Thank you.
Raghavendra
> Reviewed-by: Shaoqin Huang <shahuang@xxxxxxxxxx>
> > +
> > +     return ret;
> >   }
> >
> >   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 d39af5639ce9..86cb83bb3480 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 e3f968b38ae9..a731967b24ff 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 pages);
> >
> >   #ifdef KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE
> >   int kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int min);
> > @@ -1486,6 +1487,14 @@ static inline 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 pages)
> > +{
> > +     return -EOPNOTSUPP;
> > +}
> > +#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 d6b050786155..804470fccac7 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 pages)
> > +{
> > +     if (!kvm_arch_flush_remote_tlbs_range(kvm, gfn, 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);
>
> --
> Shaoqin
>