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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 10/24] kvm: x86/mmu: Factor out handle disconnected pt
Date: Tue, 12 Jan 2021 10:10:27 -0800	[thread overview]
Message-ID: <20210112181041.356734-11-bgardon@google.com> (raw)
In-Reply-To: <20210112181041.356734-1-bgardon@google.com>

Factor out the code to handle a disconnected subtree of the TDP paging
structure from the code to handle the change to an individual SPTE.
Future commits will build on this to allow asynchronous page freeing.

No functional change intended.

Reviewed-by: Peter Feiner <pfeiner@google.com>

Signed-off-by: Ben Gardon <bgardon@google.com>
---
 arch/x86/kvm/mmu/tdp_mmu.c | 75 +++++++++++++++++++++++---------------
 1 file changed, 46 insertions(+), 29 deletions(-)

diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 55df596696c7..e8f35cd46b4c 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -234,6 +234,49 @@ static void handle_changed_spte_dirty_log(struct kvm *kvm, int as_id, gfn_t gfn,
 	}
 }
 
+/**
+ * handle_disconnected_tdp_mmu_page - handle a pt removed from the TDP structure
+ *
+ * @kvm: kvm instance
+ * @pt: the page removed from the paging structure
+ *
+ * Given a page table that has been removed from the TDP paging structure,
+ * iterates through the page table to clear SPTEs and free child page tables.
+ */
+static void handle_disconnected_tdp_mmu_page(struct kvm *kvm, u64 *pt)
+{
+	struct kvm_mmu_page *sp;
+	gfn_t gfn;
+	int level;
+	u64 old_child_spte;
+	int i;
+
+	sp = sptep_to_sp(pt);
+	gfn = sp->gfn;
+	level = sp->role.level;
+
+	trace_kvm_mmu_prepare_zap_page(sp);
+
+	list_del(&sp->link);
+
+	if (sp->lpage_disallowed)
+		unaccount_huge_nx_page(kvm, sp);
+
+	for (i = 0; i < PT64_ENT_PER_PAGE; i++) {
+		old_child_spte = READ_ONCE(*(pt + i));
+		WRITE_ONCE(*(pt + i), 0);
+		handle_changed_spte(kvm, kvm_mmu_page_as_id(sp),
+			gfn + (i * KVM_PAGES_PER_HPAGE(level - 1)),
+			old_child_spte, 0, level - 1);
+	}
+
+	kvm_flush_remote_tlbs_with_address(kvm, gfn,
+					   KVM_PAGES_PER_HPAGE(level));
+
+	free_page((unsigned long)pt);
+	kmem_cache_free(mmu_page_header_cache, sp);
+}
+
 /**
  * handle_changed_spte - handle bookkeeping associated with an SPTE change
  * @kvm: kvm instance
@@ -254,10 +297,6 @@ static void __handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn,
 	bool was_leaf = was_present && is_last_spte(old_spte, level);
 	bool is_leaf = is_present && is_last_spte(new_spte, level);
 	bool pfn_changed = spte_to_pfn(old_spte) != spte_to_pfn(new_spte);
-	u64 *pt;
-	struct kvm_mmu_page *sp;
-	u64 old_child_spte;
-	int i;
 
 	WARN_ON(level > PT64_ROOT_MAX_LEVEL);
 	WARN_ON(level < PG_LEVEL_4K);
@@ -321,31 +360,9 @@ static void __handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn,
 	 * Recursively handle child PTs if the change removed a subtree from
 	 * the paging structure.
 	 */
-	if (was_present && !was_leaf && (pfn_changed || !is_present)) {
-		pt = spte_to_child_pt(old_spte, level);
-		sp = sptep_to_sp(pt);
-
-		trace_kvm_mmu_prepare_zap_page(sp);
-
-		list_del(&sp->link);
-
-		if (sp->lpage_disallowed)
-			unaccount_huge_nx_page(kvm, sp);
-
-		for (i = 0; i < PT64_ENT_PER_PAGE; i++) {
-			old_child_spte = READ_ONCE(*(pt + i));
-			WRITE_ONCE(*(pt + i), 0);
-			handle_changed_spte(kvm, as_id,
-				gfn + (i * KVM_PAGES_PER_HPAGE(level - 1)),
-				old_child_spte, 0, level - 1);
-		}
-
-		kvm_flush_remote_tlbs_with_address(kvm, gfn,
-						   KVM_PAGES_PER_HPAGE(level));
-
-		free_page((unsigned long)pt);
-		kmem_cache_free(mmu_page_header_cache, sp);
-	}
+	if (was_present && !was_leaf && (pfn_changed || !is_present))
+		handle_disconnected_tdp_mmu_page(kvm,
+				spte_to_child_pt(old_spte, level));
 }
 
 static void handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn,
-- 
2.30.0.284.gd98b1dd5eaa7-goog


  parent reply	other threads:[~2021-01-12 18:12 UTC|newest]

Thread overview: 72+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-12 18:10 [PATCH 00/24] Allow parallel page faults with TDP MMU Ben Gardon
2021-01-12 18:10 ` [PATCH 01/24] locking/rwlocks: Add contention detection for rwlocks Ben Gardon
2021-01-12 18:10 ` [PATCH 02/24] sched: Add needbreak " Ben Gardon
2021-01-12 18:10 ` [PATCH 03/24] sched: Add cond_resched_rwlock Ben Gardon
2021-01-12 18:10 ` [PATCH 04/24] kvm: x86/mmu: change TDP MMU yield function returns to match cond_resched Ben Gardon
2021-01-20 18:38   ` Sean Christopherson
2021-01-21 20:22     ` Paolo Bonzini
2021-01-26 14:11     ` Paolo Bonzini
2021-01-12 18:10 ` [PATCH 05/24] kvm: x86/mmu: Fix yielding in TDP MMU Ben Gardon
2021-01-20 19:28   ` Sean Christopherson
2021-01-22  1:06     ` Ben Gardon
2021-01-12 18:10 ` [PATCH 06/24] kvm: x86/mmu: Skip no-op changes in TDP MMU functions Ben Gardon
2021-01-20 19:51   ` Sean Christopherson
2021-01-25 23:51     ` Ben Gardon
2021-01-12 18:10 ` [PATCH 07/24] kvm: x86/mmu: Add comment on __tdp_mmu_set_spte Ben Gardon
2021-01-26 14:13   ` Paolo Bonzini
2021-01-12 18:10 ` [PATCH 08/24] kvm: x86/mmu: Add lockdep when setting a TDP MMU SPTE Ben Gardon
2021-01-20 19:58   ` Sean Christopherson
2021-01-26 14:13   ` Paolo Bonzini
2021-01-12 18:10 ` [PATCH 09/24] kvm: x86/mmu: Don't redundantly clear TDP MMU pt memory Ben Gardon
2021-01-20 20:06   ` Sean Christopherson
2021-01-26 14:14   ` Paolo Bonzini
2021-01-12 18:10 ` Ben Gardon [this message]
2021-01-20 20:30   ` [PATCH 10/24] kvm: x86/mmu: Factor out handle disconnected pt Sean Christopherson
2021-01-26 14:14   ` Paolo Bonzini
2021-01-12 18:10 ` [PATCH 11/24] kvm: x86/mmu: Put TDP MMU PT walks in RCU read-critical section Ben Gardon
2021-01-20 22:19   ` Sean Christopherson
2021-01-12 18:10 ` [PATCH 12/24] kvm: x86/kvm: RCU dereference tdp mmu page table links Ben Gardon
2021-01-22 18:32   ` Sean Christopherson
2021-01-26 18:17     ` Ben Gardon
2021-01-12 18:10 ` [PATCH 13/24] kvm: x86/mmu: Only free tdp_mmu pages after a grace period Ben Gardon
2021-01-12 18:10 ` [PATCH 14/24] kvm: mmu: Wrap mmu_lock lock / unlock in a function Ben Gardon
2021-01-13  2:35   ` kernel test robot
2021-01-12 18:10 ` [PATCH 15/24] kvm: mmu: Wrap mmu_lock cond_resched and needbreak Ben Gardon
2021-01-21  0:19   ` Sean Christopherson
2021-01-21 20:17     ` Paolo Bonzini
2021-01-26 14:38     ` Paolo Bonzini
2021-01-26 17:47       ` Ben Gardon
2021-01-26 17:55         ` Paolo Bonzini
2021-01-26 18:11           ` Ben Gardon
2021-01-26 20:47             ` Paolo Bonzini
2021-01-27 20:08               ` Ben Gardon
2021-01-27 20:55                 ` Paolo Bonzini
2021-01-27 21:20                   ` Ben Gardon
2021-01-28  8:18                     ` Paolo Bonzini
2021-01-12 18:10 ` [PATCH 16/24] kvm: mmu: Wrap mmu_lock assertions Ben Gardon
2021-01-26 14:29   ` Paolo Bonzini
2021-01-12 18:10 ` [PATCH 17/24] kvm: mmu: Move mmu_lock to struct kvm_arch Ben Gardon
2021-01-12 18:10 ` [PATCH 18/24] kvm: x86/mmu: Use an rwlock for the x86 TDP MMU Ben Gardon
2021-01-21  0:45   ` Sean Christopherson
2021-01-12 18:10 ` [PATCH 19/24] kvm: x86/mmu: Protect tdp_mmu_pages with a lock Ben Gardon
2021-01-21 19:22   ` Sean Christopherson
2021-01-21 21:32     ` Sean Christopherson
2021-01-26 14:27       ` Paolo Bonzini
2021-01-26 21:47         ` Ben Gardon
2021-01-26 22:02         ` Sean Christopherson
2021-01-26 22:09           ` Sean Christopherson
2021-01-27 12:40           ` Paolo Bonzini
2021-01-26 13:37   ` Paolo Bonzini
2021-01-26 21:07     ` Ben Gardon
2021-01-12 18:10 ` [PATCH 20/24] kvm: x86/mmu: Add atomic option for setting SPTEs Ben Gardon
2021-01-13  0:05   ` kernel test robot
2021-01-26 14:21   ` Paolo Bonzini
2021-01-12 18:10 ` [PATCH 21/24] kvm: x86/mmu: Use atomic ops to set SPTEs in TDP MMU map Ben Gardon
2021-01-12 18:10 ` [PATCH 22/24] kvm: x86/mmu: Flush TLBs after zap in TDP MMU PF handler Ben Gardon
2021-01-21  0:05   ` Sean Christopherson
2021-01-12 18:10 ` [PATCH 23/24] kvm: x86/mmu: Freeze SPTEs in disconnected pages Ben Gardon
2021-01-12 18:10 ` [PATCH 24/24] kvm: x86/mmu: Allow parallel page faults for the TDP MMU Ben Gardon
2021-01-21  0:55   ` Sean Christopherson
2021-01-26 21:57     ` Ben Gardon
2021-01-27 17:14       ` Sean Christopherson
2021-01-26 13:37   ` Paolo Bonzini

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