forked from Minki/linux
kvm: x86: export maximum number of mmu_page_hash collisions
Report the maximum number of mmu_page_hash collisions as a per-VM stat. This will make it easy to identify problems with the mmu_page_hash in the future. Signed-off-by: David Matlack <dmatlack@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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826da32140
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@ -821,6 +821,7 @@ struct kvm_vm_stat {
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ulong mmu_unsync;
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ulong remote_tlb_flush;
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ulong lpages;
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ulong max_mmu_page_hash_collisions;
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};
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struct kvm_vcpu_stat {
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@ -1904,17 +1904,17 @@ static void kvm_mmu_commit_zap_page(struct kvm *kvm,
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* since it has been deleted from active_mmu_pages but still can be found
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* at hast list.
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*
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* for_each_gfn_valid_sp() has skipped that kind of pages.
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* for_each_valid_sp() has skipped that kind of pages.
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*/
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#define for_each_gfn_valid_sp(_kvm, _sp, _gfn) \
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#define for_each_valid_sp(_kvm, _sp, _gfn) \
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hlist_for_each_entry(_sp, \
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&(_kvm)->arch.mmu_page_hash[kvm_page_table_hashfn(_gfn)], hash_link) \
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if ((_sp)->gfn != (_gfn) || is_obsolete_sp((_kvm), (_sp)) \
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|| (_sp)->role.invalid) {} else
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if (is_obsolete_sp((_kvm), (_sp)) || (_sp)->role.invalid) { \
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} else
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#define for_each_gfn_indirect_valid_sp(_kvm, _sp, _gfn) \
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for_each_gfn_valid_sp(_kvm, _sp, _gfn) \
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if ((_sp)->role.direct) {} else
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for_each_valid_sp(_kvm, _sp, _gfn) \
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if ((_sp)->gfn != (_gfn) || (_sp)->role.direct) {} else
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/* @sp->gfn should be write-protected at the call site */
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static bool __kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
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@ -2116,6 +2116,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
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struct kvm_mmu_page *sp;
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bool need_sync = false;
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bool flush = false;
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int collisions = 0;
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LIST_HEAD(invalid_list);
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role = vcpu->arch.mmu.base_role;
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@ -2130,7 +2131,12 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
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quadrant &= (1 << ((PT32_PT_BITS - PT64_PT_BITS) * level)) - 1;
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role.quadrant = quadrant;
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}
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for_each_gfn_valid_sp(vcpu->kvm, sp, gfn) {
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for_each_valid_sp(vcpu->kvm, sp, gfn) {
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if (sp->gfn != gfn) {
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collisions++;
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continue;
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}
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if (!need_sync && sp->unsync)
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need_sync = true;
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@ -2153,7 +2159,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
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__clear_sp_write_flooding_count(sp);
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trace_kvm_mmu_get_page(sp, false);
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return sp;
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goto out;
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}
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++vcpu->kvm->stat.mmu_cache_miss;
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@ -2183,6 +2189,9 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
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trace_kvm_mmu_get_page(sp, true);
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kvm_mmu_flush_or_zap(vcpu, &invalid_list, false, flush);
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out:
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if (collisions > vcpu->kvm->stat.max_mmu_page_hash_collisions)
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vcpu->kvm->stat.max_mmu_page_hash_collisions = collisions;
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return sp;
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}
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@ -190,6 +190,8 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
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{ "mmu_unsync", VM_STAT(mmu_unsync) },
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{ "remote_tlb_flush", VM_STAT(remote_tlb_flush) },
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{ "largepages", VM_STAT(lpages) },
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{ "max_mmu_page_hash_collisions",
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VM_STAT(max_mmu_page_hash_collisions) },
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{ NULL }
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};
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