Re: [PATCH v7 04/12] KVM: Allow range-based TLB invalidation from common code

[Anup Patel]

On Sat, Jul 22, 2023 at 7:52 AM Raghavendra Rao Ananta
<rananta@xxxxxxxxxx> 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>
> Reviewed-by: Shaoqin Huang <shahuang@xxxxxxxxxx>

For KVM RISC-V:
Reviewed-by: Anup Patel <anup@xxxxxxxxxxxxxx>

Regards,
Anup

> ---
>  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..eb88d25f9896 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);
> +
> +       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);
> --
> 2.41.0.487.g6d72f3e995-goog
>