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From: Sean Christopherson <seanjc@google.com>
To: Marc Zyngier <maz@kernel.org>,
	Huacai Chen <chenhuacai@kernel.org>,
	Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>,
	Paul Mackerras <paulus@ozlabs.org>,
	Paolo Bonzini <pbonzini@redhat.com>
Cc: James Morse <james.morse@arm.com>,
	Julien Thierry <julien.thierry.kdev@gmail.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Sean Christopherson <seanjc@google.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu, linux-mips@vger.kernel.org,
	kvm@vger.kernel.org, kvm-ppc@vger.kernel.org,
	linux-kernel@vger.kernel.org, Ben Gardon <bgardon@google.com>
Subject: [PATCH 01/18] KVM: x86/mmu: Coalesce TDP MMU TLB flushes when zapping collapsible SPTEs
Date: Thu, 25 Mar 2021 19:19:40 -0700	[thread overview]
Message-ID: <20210326021957.1424875-2-seanjc@google.com> (raw)
In-Reply-To: <20210326021957.1424875-1-seanjc@google.com>

When zapping collapsible SPTEs across multiple roots, gather pending
flushes and perform a single remote TLB flush at the end, as opposed to
flushing after processing every root.

Note, flush may be cleared by the result of zap_collapsible_spte_range().
This is intended and correct, e.g. yielding may have serviced a prior
pending flush.

Cc: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/mmu/tdp_mmu.c | 22 +++++++++++++---------
 1 file changed, 13 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 08667e3cf091..463f1be6ff0d 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -1278,21 +1278,21 @@ 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 void zap_collapsible_spte_range(struct kvm *kvm,
+static bool zap_collapsible_spte_range(struct kvm *kvm,
 				       struct kvm_mmu_page *root,
-				       struct kvm_memory_slot *slot)
+				       struct kvm_memory_slot *slot,
+				       bool flush)
 {
 	gfn_t start = slot->base_gfn;
 	gfn_t end = start + slot->npages;
 	struct tdp_iter iter;
 	kvm_pfn_t pfn;
-	bool spte_set = false;
 
 	rcu_read_lock();
 
 	tdp_root_for_each_pte(iter, root, start, end) {
-		if (tdp_mmu_iter_cond_resched(kvm, &iter, spte_set)) {
-			spte_set = false;
+		if (tdp_mmu_iter_cond_resched(kvm, &iter, flush)) {
+			flush = false;
 			continue;
 		}
 
@@ -1308,12 +1308,12 @@ static void zap_collapsible_spte_range(struct kvm *kvm,
 
 		tdp_mmu_set_spte(kvm, &iter, 0);
 
-		spte_set = true;
+		flush = true;
 	}
 
 	rcu_read_unlock();
-	if (spte_set)
-		kvm_flush_remote_tlbs(kvm);
+
+	return flush;
 }
 
 /*
@@ -1324,6 +1324,7 @@ void kvm_tdp_mmu_zap_collapsible_sptes(struct kvm *kvm,
 				       struct kvm_memory_slot *slot)
 {
 	struct kvm_mmu_page *root;
+	bool flush = false;
 	int root_as_id;
 
 	for_each_tdp_mmu_root_yield_safe(kvm, root) {
@@ -1331,8 +1332,11 @@ void kvm_tdp_mmu_zap_collapsible_sptes(struct kvm *kvm,
 		if (root_as_id != slot->as_id)
 			continue;
 
-		zap_collapsible_spte_range(kvm, root, slot);
+		flush = zap_collapsible_spte_range(kvm, root, slot, flush);
 	}
+
+	if (flush)
+		kvm_flush_remote_tlbs(kvm);
 }
 
 /*
-- 
2.31.0.291.g576ba9dcdaf-goog


  reply	other threads:[~2021-03-26  2:21 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-26  2:19 [PATCH 00/18] KVM: Consolidate and optimize MMU notifiers Sean Christopherson
2021-03-26  2:19 ` Sean Christopherson [this message]
2021-03-26  2:19 ` [PATCH 02/18] KVM: x86/mmu: Move flushing for "slot" handlers to caller for legacy MMU Sean Christopherson
2021-03-26  2:19 ` [PATCH 03/18] KVM: x86/mmu: Coalesce TLB flushes when zapping collapsible SPTEs Sean Christopherson
2021-03-26  2:19 ` [PATCH 04/18] KVM: x86/mmu: Coalesce TLB flushes across address spaces for gfn range zap Sean Christopherson
2021-03-26  2:19 ` [PATCH 05/18] KVM: x86/mmu: Pass address space ID to __kvm_tdp_mmu_zap_gfn_range() Sean Christopherson
2021-03-26  2:19 ` [PATCH 06/18] KVM: x86/mmu: Pass address space ID to TDP MMU root walkers Sean Christopherson
2021-03-26  2:19 ` [PATCH 07/18] KVM: x86/mmu: Use leaf-only loop for walking TDP SPTEs when changing SPTE Sean Christopherson
2021-03-26  2:19 ` [PATCH 08/18] KVM: Move prototypes for MMU notifier callbacks to generic code Sean Christopherson
2021-03-26  2:19 ` [PATCH 09/18] KVM: Move arm64's MMU notifier trace events " Sean Christopherson
2021-03-26  2:19 ` [PATCH 10/18] KVM: Move x86's MMU notifier memslot walkers " Sean Christopherson
2021-03-31  7:52   ` Paolo Bonzini
2021-03-31 16:20     ` Sean Christopherson
2021-03-31 16:36       ` Paolo Bonzini
2021-03-26  2:19 ` [PATCH 11/18] KVM: arm64: Convert to the gfn-based MMU notifier callbacks Sean Christopherson
2021-03-26  2:19 ` [PATCH 12/18] KVM: MIPS/MMU: " Sean Christopherson
2021-03-31  7:41   ` Paolo Bonzini
2021-03-26  2:19 ` [PATCH 13/18] KVM: PPC: " Sean Christopherson
2021-03-26  2:19 ` [PATCH 14/18] KVM: Kill off the old hva-based " Sean Christopherson
2021-03-26  2:19 ` [PATCH 15/18] KVM: Take mmu_lock when handling MMU notifier iff the hva hits a memslot Sean Christopherson
2021-03-26  2:19 ` [PATCH 16/18] KVM: Don't take mmu_lock for range invalidation unless necessary Sean Christopherson
2021-03-31  7:52   ` Paolo Bonzini
2021-03-31  8:35   ` Paolo Bonzini
2021-03-31 16:41     ` Sean Christopherson
2021-03-31 16:47       ` Paolo Bonzini
2021-03-31 19:47         ` Sean Christopherson
2021-03-31 20:42           ` Paolo Bonzini
2021-03-31 21:05             ` Sean Christopherson
2021-03-31 21:22               ` Sean Christopherson
2021-03-31 21:36                 ` Paolo Bonzini
2021-03-31 21:35               ` Paolo Bonzini
2021-03-31 21:47                 ` Sean Christopherson
2021-03-31 20:15     ` Sean Christopherson
2021-03-31 20:30       ` Paolo Bonzini
2021-03-31 20:52     ` Sean Christopherson
2021-03-31 21:00       ` Paolo Bonzini
2021-03-26  2:19 ` [PATCH 17/18] KVM: x86/mmu: Allow yielding during MMU notifier unmap/zap, if possible Sean Christopherson
2021-03-26  2:19 ` [PATCH 18/18] KVM: x86/mmu: Drop trace_kvm_age_page() tracepoint Sean Christopherson
2021-03-30 18:32 ` [PATCH 00/18] KVM: Consolidate and optimize MMU notifiers Ben Gardon
2021-03-30 19:48   ` Paolo Bonzini
2021-03-30 19:58   ` Sean Christopherson
2021-03-31  7:57 ` Paolo Bonzini
2021-03-31  9:34   ` Marc Zyngier
2021-03-31  9:41     ` Paolo Bonzini

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