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From: Ben Gardon <bgardon@google.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: Paolo Bonzini <pbonzini@redhat.com>, Peter Xu <peterx@redhat.com>,
	Sean Christopherson <seanjc@google.com>,
	Peter Shier <pshier@google.com>,
	David Matlack <dmatlack@google.com>,
	Mingwei Zhang <mizhang@google.com>,
	Yulei Zhang <yulei.kernel@gmail.com>,
	Wanpeng Li <kernellwp@gmail.com>,
	Xiao Guangrong <xiaoguangrong.eric@gmail.com>,
	Kai Huang <kai.huang@intel.com>,
	Keqian Zhu <zhukeqian1@huawei.com>,
	David Hildenbrand <david@redhat.com>,
	Ben Gardon <bgardon@google.com>
Subject: [PATCH 01/15] KVM: x86/mmu: Remove redundant flushes when disabling dirty logging
Date: Mon, 15 Nov 2021 15:45:49 -0800	[thread overview]
Message-ID: <20211115234603.2908381-2-bgardon@google.com> (raw)
In-Reply-To: <20211115234603.2908381-1-bgardon@google.com>

tdp_mmu_zap_spte_atomic flushes on every zap already, so no need to
flush again after it's done.

Reviewed-by: David Matlack <dmatlack@google.com>

Signed-off-by: Ben Gardon <bgardon@google.com>
---
 arch/x86/kvm/mmu/mmu.c     |  4 +---
 arch/x86/kvm/mmu/tdp_mmu.c | 21 ++++++---------------
 arch/x86/kvm/mmu/tdp_mmu.h |  5 ++---
 3 files changed, 9 insertions(+), 21 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 354d2ca92df4..baa94acab516 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5870,9 +5870,7 @@ void kvm_mmu_zap_collapsible_sptes(struct kvm *kvm,
 
 	if (is_tdp_mmu_enabled(kvm)) {
 		read_lock(&kvm->mmu_lock);
-		flush = kvm_tdp_mmu_zap_collapsible_sptes(kvm, slot, flush);
-		if (flush)
-			kvm_arch_flush_remote_tlbs_memslot(kvm, slot);
+		kvm_tdp_mmu_zap_collapsible_sptes(kvm, slot);
 		read_unlock(&kvm->mmu_lock);
 	}
 }
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 7c5dd83e52de..b3c78568ae60 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -1364,10 +1364,9 @@ void kvm_tdp_mmu_clear_dirty_pt_masked(struct kvm *kvm,
  * Clear leaf entries which could be replaced by large mappings, for
  * GFNs within the slot.
  */
-static bool zap_collapsible_spte_range(struct kvm *kvm,
+static void zap_collapsible_spte_range(struct kvm *kvm,
 				       struct kvm_mmu_page *root,
-				       const struct kvm_memory_slot *slot,
-				       bool flush)
+				       const struct kvm_memory_slot *slot)
 {
 	gfn_t start = slot->base_gfn;
 	gfn_t end = start + slot->npages;
@@ -1378,10 +1377,8 @@ static bool zap_collapsible_spte_range(struct kvm *kvm,
 
 	tdp_root_for_each_pte(iter, root, start, end) {
 retry:
-		if (tdp_mmu_iter_cond_resched(kvm, &iter, flush, true)) {
-			flush = false;
+		if (tdp_mmu_iter_cond_resched(kvm, &iter, false, true))
 			continue;
-		}
 
 		if (!is_shadow_present_pte(iter.old_spte) ||
 		    !is_last_spte(iter.old_spte, iter.level))
@@ -1401,30 +1398,24 @@ static bool zap_collapsible_spte_range(struct kvm *kvm,
 			iter.old_spte = READ_ONCE(*rcu_dereference(iter.sptep));
 			goto retry;
 		}
-		flush = true;
 	}
 
 	rcu_read_unlock();
-
-	return flush;
 }
 
 /*
  * Clear non-leaf entries (and free associated page tables) which could
  * be replaced by large mappings, for GFNs within the slot.
  */
-bool kvm_tdp_mmu_zap_collapsible_sptes(struct kvm *kvm,
-				       const struct kvm_memory_slot *slot,
-				       bool flush)
+void kvm_tdp_mmu_zap_collapsible_sptes(struct kvm *kvm,
+				       const struct kvm_memory_slot *slot)
 {
 	struct kvm_mmu_page *root;
 
 	lockdep_assert_held_read(&kvm->mmu_lock);
 
 	for_each_tdp_mmu_root_yield_safe(kvm, root, slot->as_id, true)
-		flush = zap_collapsible_spte_range(kvm, root, slot, flush);
-
-	return flush;
+		zap_collapsible_spte_range(kvm, root, slot);
 }
 
 /*
diff --git a/arch/x86/kvm/mmu/tdp_mmu.h b/arch/x86/kvm/mmu/tdp_mmu.h
index 476b133544dd..3899004a5d91 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.h
+++ b/arch/x86/kvm/mmu/tdp_mmu.h
@@ -64,9 +64,8 @@ void kvm_tdp_mmu_clear_dirty_pt_masked(struct kvm *kvm,
 				       struct kvm_memory_slot *slot,
 				       gfn_t gfn, unsigned long mask,
 				       bool wrprot);
-bool kvm_tdp_mmu_zap_collapsible_sptes(struct kvm *kvm,
-				       const struct kvm_memory_slot *slot,
-				       bool flush);
+void kvm_tdp_mmu_zap_collapsible_sptes(struct kvm *kvm,
+				       const struct kvm_memory_slot *slot);
 
 bool kvm_tdp_mmu_write_protect_gfn(struct kvm *kvm,
 				   struct kvm_memory_slot *slot, gfn_t gfn,
-- 
2.34.0.rc1.387.gb447b232ab-goog


  reply	other threads:[~2021-11-16  3:16 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-15 23:45 [PATCH 00/15] Currently disabling dirty logging with the TDP MMU is extremely slow. On a 96 vCPU / 96G VM it takes ~45 seconds to disable dirty logging with the TDP MMU, as opposed to ~3.5 seconds with the legacy MMU. This series optimizes TLB flushes and introduces in-place large page promotion, to bring the disable dirty log time down to ~2 seconds Ben Gardon
2021-11-15 23:45 ` Ben Gardon [this message]
2021-11-18  8:26   ` [PATCH 01/15] KVM: x86/mmu: Remove redundant flushes when disabling dirty logging Paolo Bonzini
2021-11-15 23:45 ` [PATCH 02/15] KVM: x86/mmu: Introduce vcpu_make_spte Ben Gardon
2021-11-15 23:45 ` [PATCH 03/15] KVM: x86/mmu: Factor wrprot for nested PML out of make_spte Ben Gardon
2021-11-15 23:45 ` [PATCH 04/15] KVM: x86/mmu: Factor mt_mask " Ben Gardon
2021-11-15 23:45 ` [PATCH 05/15] KVM: x86/mmu: Remove need for a vcpu from kvm_slot_page_track_is_active Ben Gardon
2021-11-18  8:25   ` Paolo Bonzini
2021-11-15 23:45 ` [PATCH 06/15] KVM: x86/mmu: Remove need for a vcpu from mmu_try_to_unsync_pages Ben Gardon
2021-11-18  8:25   ` Paolo Bonzini
2021-11-15 23:45 ` [PATCH 07/15] KVM: x86/mmu: Factor shadow_zero_check out of make_spte Ben Gardon
2021-11-15 23:45 ` [PATCH 08/15] KVM: x86/mmu: Replace vcpu argument with kvm pointer in make_spte Ben Gardon
2021-11-15 23:45 ` [PATCH 09/15] KVM: x86/mmu: Factor out the meat of reset_tdp_shadow_zero_bits_mask Ben Gardon
2021-11-15 23:45 ` [PATCH 10/15] KVM: x86/mmu: Propagate memslot const qualifier Ben Gardon
2021-11-18  8:27   ` Paolo Bonzini
2021-11-15 23:45 ` [PATCH 11/15] KVM: x86/MMU: Refactor vmx_get_mt_mask Ben Gardon
2021-11-18  8:30   ` Paolo Bonzini
2021-11-18 15:30     ` Sean Christopherson
2021-11-19  9:02       ` Paolo Bonzini
2021-11-22 18:11         ` Ben Gardon
2021-11-22 18:46           ` Sean Christopherson
2021-11-15 23:46 ` [PATCH 12/15] KVM: x86/mmu: Factor out part of vmx_get_mt_mask which does not depend on vcpu Ben Gardon
2021-11-15 23:46 ` [PATCH 13/15] KVM: x86/mmu: Add try_get_mt_mask to x86_ops Ben Gardon
2021-11-15 23:46 ` [PATCH 14/15] KVM: x86/mmu: Make kvm_is_mmio_pfn usable outside of spte.c Ben Gardon
2021-11-15 23:46 ` [PATCH 15/15] KVM: x86/mmu: Promote pages in-place when disabling dirty logging Ben Gardon
2021-11-25  4:18   ` Peter Xu
2021-11-29 18:31     ` Ben Gardon
2021-11-30  0:13       ` Sean Christopherson
2021-11-30  7:28       ` Peter Xu
2021-11-30 16:01         ` Sean Christopherson
2021-12-01  1:59           ` Peter Xu
2021-11-15 23:58 ` [PATCH 00/15] Currently disabling dirty logging with the TDP MMU is extremely slow. On a 96 vCPU / 96G VM it takes ~45 seconds to disable dirty logging with the TDP MMU, as opposed to ~3.5 seconds with the legacy MMU. This series optimizes TLB flushes and introduces in-place large page promotion, to bring the disable dirty log time down to ~2 seconds Ben Gardon

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