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KVM: x86/mmu: Revert "KVM: x86/mmu: Remove is_obsolete() call" 

Now that the fast invalidate mechanism has been reintroduced, restore
the performance tweaks for fast invalidation that existed prior to its
removal.

Paraphrasing the original changelog (commit 5ff0568374 was itself a
partial revert):

  Don't force reloading the remote mmu when zapping an obsolete page, as
  a MMU_RELOAD request has already been issued by kvm_mmu_zap_all_fast()
  immediately after incrementing mmu_valid_gen, i.e. after marking pages
  obsolete.

This reverts commit 5ff0568374.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
alistair/sunxi64-5.4-dsi
Sean Christopherson 2019-09-12 19:46:10 -07:00 committed by Paolo Bonzini
parent 31741eb11a
commit 10605204e9
2 changed files with 24 additions and 6 deletions
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29
arch/x86/kvm/mmu.c
View File

@ -2752,7 +2752,12 @@ static bool __kvm_mmu_prepare_zap_page(struct kvm *kvm,
} else {
list_move(&sp->link, &kvm->arch.active_mmu_pages);
if (!sp->role.invalid)
/*
* Obsolete pages cannot be used on any vCPUs, see the comment
* in kvm_mmu_zap_all_fast(). Note, is_obsolete_sp() also
* treats invalid shadow pages as being obsolete.
*/
if (!is_obsolete_sp(kvm, sp))
kvm_reload_remote_mmus(kvm);
}
@ -5675,7 +5680,6 @@ int kvm_mmu_create(struct kvm_vcpu *vcpu)
static void kvm_zap_obsolete_pages(struct kvm *kvm)
{
struct kvm_mmu_page *sp, *node;
LIST_HEAD(invalid_list);
int nr_zapped, batch = 0;
restart:
@ -5708,8 +5712,8 @@ restart:
goto restart;
}
if (__kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list,
&nr_zapped)) {
if (__kvm_mmu_prepare_zap_page(kvm, sp,
&kvm->arch.zapped_obsolete_pages, &nr_zapped)) {
batch += nr_zapped;
goto restart;
}
@ -5720,7 +5724,7 @@ restart:
* KVM is not in the middle of a lockless shadow page table walk, which
* may reference the pages.
*/
kvm_mmu_commit_zap_page(kvm, &invalid_list);
kvm_mmu_commit_zap_page(kvm, &kvm->arch.zapped_obsolete_pages);
}
/*
@ -5752,6 +5756,11 @@ static void kvm_mmu_zap_all_fast(struct kvm *kvm)
spin_unlock(&kvm->mmu_lock);
}
static bool kvm_has_zapped_obsolete_pages(struct kvm *kvm)
{
return unlikely(!list_empty_careful(&kvm->arch.zapped_obsolete_pages));
}
static void kvm_mmu_invalidate_zap_pages_in_memslot(struct kvm *kvm,
struct kvm_memory_slot *slot,
struct kvm_page_track_notifier_node *node)
@ -6022,16 +6031,24 @@ mmu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
* want to shrink a VM that only started to populate its MMU
* anyway.
*/
if (!kvm->arch.n_used_mmu_pages)
if (!kvm->arch.n_used_mmu_pages &&
!kvm_has_zapped_obsolete_pages(kvm))
continue;
idx = srcu_read_lock(&kvm->srcu);
spin_lock(&kvm->mmu_lock);
if (kvm_has_zapped_obsolete_pages(kvm)) {
kvm_mmu_commit_zap_page(kvm,
&kvm->arch.zapped_obsolete_pages);
goto unlock;
}
if (prepare_zap_oldest_mmu_page(kvm, &invalid_list))
freed++;
kvm_mmu_commit_zap_page(kvm, &invalid_list);
unlock:
spin_unlock(&kvm->mmu_lock);
srcu_read_unlock(&kvm->srcu, idx);

1
arch/x86/kvm/x86.c
View File

@ -9425,6 +9425,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
INIT_HLIST_HEAD(&kvm->arch.mask_notifier_list);
INIT_LIST_HEAD(&kvm->arch.active_mmu_pages);
INIT_LIST_HEAD(&kvm->arch.zapped_obsolete_pages);
INIT_LIST_HEAD(&kvm->arch.assigned_dev_head);
atomic_set(&kvm->arch.noncoherent_dma_count, 0);