Re: [PATCH v7 05/12] KVM: Move kvm_arch_flush_remote_tlbs_memslot() to common code

[Anup Patel <anup@brainfault.org>]

On Sat, Jul 22, 2023 at 7:53 AM Raghavendra Rao Ananta
<rananta@google.com> wrote:
>
> From: David Matlack <dmatlack@google.com>
>
> Move kvm_arch_flush_remote_tlbs_memslot() to common code and drop
> "arch_" from the name. kvm_arch_flush_remote_tlbs_memslot() is just a
> range-based TLB invalidation where the range is defined by the memslot.
> Now that kvm_flush_remote_tlbs_range() can be called from common code we
> can just use that and drop a bunch of duplicate code from the arch
> directories.
>
> Note this adds a lockdep assertion for slots_lock being held when
> calling kvm_flush_remote_tlbs_memslot(), which was previously only
> asserted on x86. MIPS has calls to kvm_flush_remote_tlbs_memslot(),
> but they all hold the slots_lock, so the lockdep assertion continues to
> hold true.
>
> Also drop the CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT ifdef gating
> kvm_flush_remote_tlbs_memslot(), since it is no longer necessary.
>
> 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>

For KVM RISC-V:
Acked-by: Anup Patel <anup@brainfault.org>

Thanks,
Anup

> ---
>  arch/arm64/kvm/arm.c     |  6 ------
>  arch/mips/kvm/mips.c     | 10 ++--------
>  arch/riscv/kvm/mmu.c     |  6 ------
>  arch/x86/kvm/mmu/mmu.c   | 16 +---------------
>  arch/x86/kvm/x86.c       |  2 +-
>  include/linux/kvm_host.h |  7 +++----
>  virt/kvm/kvm_main.c      | 18 ++++++++++++++++--
>  7 files changed, 23 insertions(+), 42 deletions(-)
>
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index c2c14059f6a8..ed7bef4d970b 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -1525,12 +1525,6 @@ void kvm_arch_sync_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot)
>
>  }
>
> -void kvm_arch_flush_remote_tlbs_memslot(struct kvm *kvm,
> -                                       const struct kvm_memory_slot *memslot)
> -{
> -       kvm_flush_remote_tlbs(kvm);
> -}
> -
>  static int kvm_vm_ioctl_set_device_addr(struct kvm *kvm,
>                                         struct kvm_arm_device_addr *dev_addr)
>  {
> diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
> index 4b7bc39a4173..231ac052b506 100644
> --- a/arch/mips/kvm/mips.c
> +++ b/arch/mips/kvm/mips.c
> @@ -199,7 +199,7 @@ void kvm_arch_flush_shadow_memslot(struct kvm *kvm,
>         /* Flush slot from GPA */
>         kvm_mips_flush_gpa_pt(kvm, slot->base_gfn,
>                               slot->base_gfn + slot->npages - 1);
> -       kvm_arch_flush_remote_tlbs_memslot(kvm, slot);
> +       kvm_flush_remote_tlbs_memslot(kvm, slot);
>         spin_unlock(&kvm->mmu_lock);
>  }
>
> @@ -235,7 +235,7 @@ void kvm_arch_commit_memory_region(struct kvm *kvm,
>                 needs_flush = kvm_mips_mkclean_gpa_pt(kvm, new->base_gfn,
>                                         new->base_gfn + new->npages - 1);
>                 if (needs_flush)
> -                       kvm_arch_flush_remote_tlbs_memslot(kvm, new);
> +                       kvm_flush_remote_tlbs_memslot(kvm, new);
>                 spin_unlock(&kvm->mmu_lock);
>         }
>  }
> @@ -987,12 +987,6 @@ int kvm_arch_flush_remote_tlbs(struct kvm *kvm)
>         return 1;
>  }
>
> -void kvm_arch_flush_remote_tlbs_memslot(struct kvm *kvm,
> -                                       const struct kvm_memory_slot *memslot)
> -{
> -       kvm_flush_remote_tlbs(kvm);
> -}
> -
>  int kvm_arch_vm_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg)
>  {
>         int r;
> diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
> index f2eb47925806..97e129620686 100644
> --- a/arch/riscv/kvm/mmu.c
> +++ b/arch/riscv/kvm/mmu.c
> @@ -406,12 +406,6 @@ void kvm_arch_sync_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot)
>  {
>  }
>
> -void kvm_arch_flush_remote_tlbs_memslot(struct kvm *kvm,
> -                                       const struct kvm_memory_slot *memslot)
> -{
> -       kvm_flush_remote_tlbs(kvm);
> -}
> -
>  void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free)
>  {
>  }
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index eb88d25f9896..efbe394da1a6 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -6669,7 +6669,7 @@ static void kvm_rmap_zap_collapsible_sptes(struct kvm *kvm,
>          */
>         if (walk_slot_rmaps(kvm, slot, kvm_mmu_zap_collapsible_spte,
>                             PG_LEVEL_4K, KVM_MAX_HUGEPAGE_LEVEL - 1, true))
> -               kvm_arch_flush_remote_tlbs_memslot(kvm, slot);
> +               kvm_flush_remote_tlbs_memslot(kvm, slot);
>  }
>
>  void kvm_mmu_zap_collapsible_sptes(struct kvm *kvm,
> @@ -6688,20 +6688,6 @@ void kvm_mmu_zap_collapsible_sptes(struct kvm *kvm,
>         }
>  }
>
> -void kvm_arch_flush_remote_tlbs_memslot(struct kvm *kvm,
> -                                       const struct kvm_memory_slot *memslot)
> -{
> -       /*
> -        * All current use cases for flushing the TLBs for a specific memslot
> -        * related to dirty logging, and many do the TLB flush out of mmu_lock.
> -        * The interaction between the various operations on memslot must be
> -        * serialized by slots_locks to ensure the TLB flush from one operation
> -        * is observed by any other operation on the same memslot.
> -        */
> -       lockdep_assert_held(&kvm->slots_lock);
> -       kvm_flush_remote_tlbs_range(kvm, memslot->base_gfn, memslot->npages);
> -}
> -
>  void kvm_mmu_slot_leaf_clear_dirty(struct kvm *kvm,
>                                    const struct kvm_memory_slot *memslot)
>  {
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index a6b9bea62fb8..faeb2e307b36 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -12751,7 +12751,7 @@ static void kvm_mmu_slot_apply_flags(struct kvm *kvm,
>                  * See is_writable_pte() for more details (the case involving
>                  * access-tracked SPTEs is particularly relevant).
>                  */
> -               kvm_arch_flush_remote_tlbs_memslot(kvm, new);
> +               kvm_flush_remote_tlbs_memslot(kvm, new);
>         }
>  }
>
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index a731967b24ff..45899ce9ed31 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -1360,6 +1360,8 @@ 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);
> +void kvm_flush_remote_tlbs_memslot(struct kvm *kvm,
> +                                  const struct kvm_memory_slot *memslot);
>
>  #ifdef KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE
>  int kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int min);
> @@ -1388,10 +1390,7 @@ void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
>                                         unsigned long mask);
>  void kvm_arch_sync_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot);
>
> -#ifdef CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT
> -void kvm_arch_flush_remote_tlbs_memslot(struct kvm *kvm,
> -                                       const struct kvm_memory_slot *memslot);
> -#else /* !CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT */
> +#ifndef CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT
>  int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log);
>  int kvm_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log,
>                       int *is_dirty, struct kvm_memory_slot **memslot);
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 804470fccac7..58213cc4b9b9 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -379,6 +379,20 @@ void kvm_flush_remote_tlbs_range(struct kvm *kvm, gfn_t gfn, u64 pages)
>         kvm_flush_remote_tlbs(kvm);
>  }
>
> +void kvm_flush_remote_tlbs_memslot(struct kvm *kvm,
> +                                  const struct kvm_memory_slot *memslot)
> +{
> +       /*
> +        * All current use cases for flushing the TLBs for a specific memslot
> +        * related to dirty logging, and many do the TLB flush out of mmu_lock.
> +        * The interaction between the various operations on memslot must be
> +        * serialized by slots_locks to ensure the TLB flush from one operation
> +        * is observed by any other operation on the same memslot.
> +        */
> +       lockdep_assert_held(&kvm->slots_lock);
> +       kvm_flush_remote_tlbs_range(kvm, memslot->base_gfn, memslot->npages);
> +}
> +
>  static void kvm_flush_shadow_all(struct kvm *kvm)
>  {
>         kvm_arch_flush_shadow_all(kvm);
> @@ -2191,7 +2205,7 @@ static int kvm_get_dirty_log_protect(struct kvm *kvm, struct kvm_dirty_log *log)
>         }
>
>         if (flush)
> -               kvm_arch_flush_remote_tlbs_memslot(kvm, memslot);
> +               kvm_flush_remote_tlbs_memslot(kvm, memslot);
>
>         if (copy_to_user(log->dirty_bitmap, dirty_bitmap_buffer, n))
>                 return -EFAULT;
> @@ -2308,7 +2322,7 @@ static int kvm_clear_dirty_log_protect(struct kvm *kvm,
>         KVM_MMU_UNLOCK(kvm);
>
>         if (flush)
> -               kvm_arch_flush_remote_tlbs_memslot(kvm, memslot);
> +               kvm_flush_remote_tlbs_memslot(kvm, memslot);
>
>         return 0;
>  }
> --
> 2.41.0.487.g6d72f3e995-goog
>