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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>,
	Peter Feiner <pfeiner@google.com>,
	Junaid Shahid <junaids@google.com>,
	Jim Mattson <jmattson@google.com>,
	Yulei Zhang <yulei.kernel@gmail.com>,
	Wanpeng Li <kernellwp@gmail.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Xiao Guangrong <xiaoguangrong.eric@gmail.com>,
	Ben Gardon <bgardon@google.com>
Subject: [PATCH 10/13] KVM: x86/mmu: Allow zapping collapsible SPTEs to use MMU read lock
Date: Wed, 31 Mar 2021 14:08:38 -0700	[thread overview]
Message-ID: <20210331210841.3996155-11-bgardon@google.com> (raw)
In-Reply-To: <20210331210841.3996155-1-bgardon@google.com>

To speed the process of disabling dirty logging, change the TDP MMU
function which zaps collapsible SPTEs to run under the MMU read lock.

Signed-off-by: Ben Gardon <bgardon@google.com>
---
 arch/x86/kvm/mmu/mmu.c     |  9 ++++++---
 arch/x86/kvm/mmu/tdp_mmu.c | 17 +++++++++++++----
 2 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index dcbfc784cf2f..81967b4e7d76 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5610,10 +5610,13 @@ void kvm_mmu_zap_collapsible_sptes(struct kvm *kvm,
 
 	write_lock(&kvm->mmu_lock);
 	slot_handle_leaf(kvm, slot, kvm_mmu_zap_collapsible_spte, true);
-
-	if (is_tdp_mmu_enabled(kvm))
-		kvm_tdp_mmu_zap_collapsible_sptes(kvm, slot);
 	write_unlock(&kvm->mmu_lock);
+
+	if (is_tdp_mmu_enabled(kvm)) {
+		read_lock(&kvm->mmu_lock);
+		kvm_tdp_mmu_zap_collapsible_sptes(kvm, memslot);
+		read_unlock(&kvm->mmu_lock);
+	}
 }
 
 void kvm_arch_flush_remote_tlbs_memslot(struct kvm *kvm,
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 0e99e4675dd4..862acb868abd 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -1335,7 +1335,8 @@ static void zap_collapsible_spte_range(struct kvm *kvm,
 	rcu_read_lock();
 
 	tdp_root_for_each_pte(iter, root, start, end) {
-		if (tdp_mmu_iter_cond_resched(kvm, &iter, spte_set, false)) {
+retry:
+		if (tdp_mmu_iter_cond_resched(kvm, &iter, spte_set, true)) {
 			spte_set = false;
 			continue;
 		}
@@ -1350,8 +1351,14 @@ static void zap_collapsible_spte_range(struct kvm *kvm,
 							    pfn, PG_LEVEL_NUM))
 			continue;
 
-		tdp_mmu_set_spte(kvm, &iter, 0);
-
+		if (!tdp_mmu_zap_spte_atomic(kvm, &iter)) {
+			/*
+			 * The iter must explicitly re-read the SPTE because
+			 * the atomic cmpxchg failed.
+			 */
+			iter.old_spte = READ_ONCE(*rcu_dereference(iter.sptep));
+			goto retry;
+		}
 		spte_set = true;
 	}
 
@@ -1370,7 +1377,9 @@ void kvm_tdp_mmu_zap_collapsible_sptes(struct kvm *kvm,
 	struct kvm_mmu_page *root;
 	int root_as_id;
 
-	for_each_tdp_mmu_root_yield_safe(kvm, root, false) {
+	lockdep_assert_held_read(&kvm->mmu_lock);
+
+	for_each_tdp_mmu_root_yield_safe(kvm, root, true) {
 		root_as_id = kvm_mmu_page_as_id(root);
 		if (root_as_id != slot->as_id)
 			continue;
-- 
2.31.0.291.g576ba9dcdaf-goog


  parent reply	other threads:[~2021-03-31 21:10 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-31 21:08 [PATCH 00/13] More parallel operations for the TDP MMU Ben Gardon
2021-03-31 21:08 ` [PATCH 01/13] KVM: x86/mmu: Re-add const qualifier in kvm_tdp_mmu_zap_collapsible_sptes Ben Gardon
2021-03-31 21:08 ` [PATCH 02/13] KVM: x86/mmu: Move kvm_mmu_(get|put)_root to TDP MMU Ben Gardon
2021-03-31 21:08 ` [PATCH 03/13] KVM: x86/mmu: use tdp_mmu_free_sp to free roots Ben Gardon
2021-03-31 21:08 ` [PATCH 04/13] KVM: x86/mmu: Merge TDP MMU put and free root Ben Gardon
2021-03-31 21:08 ` [PATCH 05/13] KVM: x86/mmu: comment for_each_tdp_mmu_root requires MMU write lock Ben Gardon
2021-03-31 21:08 ` [PATCH 06/13] KVM: x86/mmu: Refactor yield safe root iterator Ben Gardon
2021-03-31 21:08 ` [PATCH 07/13] KVM: x86/mmu: Make TDP MMU root refcount atomic Ben Gardon
2021-03-31 22:21   ` Sean Christopherson
2021-04-01 16:50     ` Ben Gardon
2021-03-31 21:08 ` [PATCH 08/13] KVM: x86/mmu: Protect the tdp_mmu_roots list with RCU Ben Gardon
2021-04-01  9:37   ` Paolo Bonzini
2021-04-01 16:48     ` Ben Gardon
2021-04-01 13:16   ` kernel test robot
2021-04-01 16:50     ` Ben Gardon
2021-03-31 21:08 ` [PATCH 09/13] KVM: x86/mmu: Allow zap gfn range to operate under the mmu read lock Ben Gardon
2021-04-01  9:58   ` Paolo Bonzini
2021-04-01 16:50     ` Ben Gardon
2021-03-31 21:08 ` Ben Gardon [this message]
2021-04-01 10:12   ` [PATCH 10/13] KVM: x86/mmu: Allow zapping collapsible SPTEs to use MMU " Paolo Bonzini
2021-03-31 21:08 ` [PATCH 11/13] KVM: x86/mmu: Allow enabling / disabling dirty logging under " Ben Gardon
2021-03-31 21:08 ` [PATCH 12/13] KVM: x86/mmu: Fast invalidation for TDP MMU Ben Gardon
2021-03-31 22:27   ` Sean Christopherson
2021-04-01 16:50     ` Ben Gardon
2021-04-01 10:36   ` Paolo Bonzini
2021-04-01 16:50     ` Ben Gardon
2021-04-01 17:02       ` Paolo Bonzini
2021-03-31 21:08 ` [PATCH 13/13] KVM: x86/mmu: Tear down roots in fast invalidation thread Ben Gardon
2021-03-31 22:29   ` Sean Christopherson
2021-04-01 10:41     ` Paolo Bonzini
2021-04-01 10:37   ` Paolo Bonzini
2021-04-01 10:43 ` [PATCH 00/13] More parallel operations for the TDP MMU Paolo Bonzini

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