提交 14881998 编写于 作者: B Ben Gardon 提交者: Paolo Bonzini

kvm: x86/mmu: Support disabling dirty logging for the tdp MMU

Dirty logging ultimately breaks down MMU mappings to 4k granularity.
When dirty logging is no longer needed, these granaular mappings
represent a useless performance penalty. When dirty logging is disabled,
search the paging structure for mappings that could be re-constituted
into a large page mapping. Zap those mappings so that they can be
faulted in again at a higher mapping level.

Tested by running kvm-unit-tests and KVM selftests on an Intel Haswell
machine. This series introduced no new failures.

This series can be viewed in Gerrit at:
	https://linux-review.googlesource.com/c/virt/kvm/kvm/+/2538Signed-off-by: NBen Gardon <bgardon@google.com>
Message-Id: <20201014182700.2888246-17-bgardon@google.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
上级 a6a0b05d
......@@ -5544,6 +5544,9 @@ void kvm_mmu_zap_collapsible_sptes(struct kvm *kvm,
spin_lock(&kvm->mmu_lock);
slot_handle_leaf(kvm, (struct kvm_memory_slot *)memslot,
kvm_mmu_zap_collapsible_spte, true);
if (kvm->arch.tdp_mmu_enabled)
kvm_tdp_mmu_zap_collapsible_sptes(kvm, memslot);
spin_unlock(&kvm->mmu_lock);
}
......
......@@ -1020,3 +1020,61 @@ bool kvm_tdp_mmu_slot_set_dirty(struct kvm *kvm, struct kvm_memory_slot *slot)
return spte_set;
}
/*
* Clear non-leaf entries (and free associated page tables) which could
* be replaced by large mappings, for GFNs within the slot.
*/
static void zap_collapsible_spte_range(struct kvm *kvm,
struct kvm_mmu_page *root,
gfn_t start, gfn_t end)
{
struct tdp_iter iter;
kvm_pfn_t pfn;
bool spte_set = false;
tdp_root_for_each_pte(iter, root, start, end) {
if (!is_shadow_present_pte(iter.old_spte) ||
is_last_spte(iter.old_spte, iter.level))
continue;
pfn = spte_to_pfn(iter.old_spte);
if (kvm_is_reserved_pfn(pfn) ||
!PageTransCompoundMap(pfn_to_page(pfn)))
continue;
tdp_mmu_set_spte(kvm, &iter, 0);
spte_set = tdp_mmu_iter_flush_cond_resched(kvm, &iter);
}
if (spte_set)
kvm_flush_remote_tlbs(kvm);
}
/*
* Clear non-leaf entries (and free associated page tables) which could
* be replaced by large mappings, for GFNs within the slot.
*/
void kvm_tdp_mmu_zap_collapsible_sptes(struct kvm *kvm,
const struct kvm_memory_slot *slot)
{
struct kvm_mmu_page *root;
int root_as_id;
for_each_tdp_mmu_root(kvm, root) {
root_as_id = kvm_mmu_page_as_id(root);
if (root_as_id != slot->as_id)
continue;
/*
* Take a reference on the root so that it cannot be freed if
* this thread releases the MMU lock and yields in this loop.
*/
kvm_mmu_get_root(kvm, root);
zap_collapsible_spte_range(kvm, root, slot->base_gfn,
slot->base_gfn + slot->npages);
kvm_mmu_put_root(kvm, root);
}
}
......@@ -38,4 +38,6 @@ void kvm_tdp_mmu_clear_dirty_pt_masked(struct kvm *kvm,
gfn_t gfn, unsigned long mask,
bool wrprot);
bool kvm_tdp_mmu_slot_set_dirty(struct kvm *kvm, struct kvm_memory_slot *slot);
void kvm_tdp_mmu_zap_collapsible_sptes(struct kvm *kvm,
const struct kvm_memory_slot *slot);
#endif /* __KVM_X86_MMU_TDP_MMU_H */
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