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 v2 11/13] KVM: x86/mmu: Allow enabling / disabling dirty logging under MMU read lock
Date: Thu, 1 Apr 2021 16:37:34 -0700 [thread overview]
Message-ID: <20210401233736.638171-12-bgardon@google.com> (raw)
In-Reply-To: <20210401233736.638171-1-bgardon@google.com>
To reduce lock contention and interference with page fault handlers,
allow the TDP MMU functions which enable and disable dirty logging
to operate under the MMU read lock.
Signed-off-by: Ben Gardon <bgardon@google.com>
---
arch/x86/kvm/mmu/mmu.c | 16 +++++++---
arch/x86/kvm/mmu/tdp_mmu.c | 62 ++++++++++++++++++++++++++++++--------
2 files changed, 61 insertions(+), 17 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 5939813e3043..a3837f8ad4ed 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5543,10 +5543,14 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm,
write_lock(&kvm->mmu_lock);
flush = slot_handle_level(kvm, memslot, slot_rmap_write_protect,
start_level, KVM_MAX_HUGEPAGE_LEVEL, false);
- if (is_tdp_mmu_enabled(kvm))
- flush |= kvm_tdp_mmu_wrprot_slot(kvm, memslot, PG_LEVEL_4K);
write_unlock(&kvm->mmu_lock);
+ if (is_tdp_mmu_enabled(kvm)) {
+ read_lock(&kvm->mmu_lock);
+ flush |= kvm_tdp_mmu_wrprot_slot(kvm, memslot, PG_LEVEL_4K);
+ read_unlock(&kvm->mmu_lock);
+ }
+
/*
* We can flush all the TLBs out of the mmu lock without TLB
* corruption since we just change the spte from writable to
@@ -5649,10 +5653,14 @@ void kvm_mmu_slot_leaf_clear_dirty(struct kvm *kvm,
write_lock(&kvm->mmu_lock);
flush = slot_handle_leaf(kvm, memslot, __rmap_clear_dirty, false);
- if (is_tdp_mmu_enabled(kvm))
- flush |= kvm_tdp_mmu_clear_dirty_slot(kvm, memslot);
write_unlock(&kvm->mmu_lock);
+ if (is_tdp_mmu_enabled(kvm)) {
+ read_lock(&kvm->mmu_lock);
+ flush |= kvm_tdp_mmu_clear_dirty_slot(kvm, memslot);
+ read_unlock(&kvm->mmu_lock);
+ }
+
/*
* It's also safe to flush TLBs out of mmu lock here as currently this
* function is only used for dirty logging, in which case flushing TLB
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 0e6ffa04e5e1..501722a524a7 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -496,8 +496,9 @@ static void handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn,
}
/*
- * tdp_mmu_set_spte_atomic - Set a TDP MMU SPTE atomically and handle the
- * associated bookkeeping
+ * tdp_mmu_set_spte_atomic_no_dirty_log - Set a TDP MMU SPTE atomically
+ * and handle the associated bookkeeping, but do not mark the page dirty
+ * in KVM's dirty bitmaps.
*
* @kvm: kvm instance
* @iter: a tdp_iter instance currently on the SPTE that should be set
@@ -505,9 +506,9 @@ static void handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn,
* Returns: true if the SPTE was set, false if it was not. If false is returned,
* this function will have no side-effects.
*/
-static inline bool tdp_mmu_set_spte_atomic(struct kvm *kvm,
- struct tdp_iter *iter,
- u64 new_spte)
+static inline bool tdp_mmu_set_spte_atomic_no_dirty_log(struct kvm *kvm,
+ struct tdp_iter *iter,
+ u64 new_spte)
{
lockdep_assert_held_read(&kvm->mmu_lock);
@@ -522,12 +523,25 @@ static inline bool tdp_mmu_set_spte_atomic(struct kvm *kvm,
new_spte) != iter->old_spte)
return false;
- handle_changed_spte(kvm, iter->as_id, iter->gfn, iter->old_spte,
- new_spte, iter->level, true);
+ __handle_changed_spte(kvm, iter->as_id, iter->gfn, iter->old_spte,
+ new_spte, iter->level, true);
+ handle_changed_spte_acc_track(iter->old_spte, new_spte, iter->level);
return true;
}
+static inline bool tdp_mmu_set_spte_atomic(struct kvm *kvm,
+ struct tdp_iter *iter,
+ u64 new_spte)
+{
+ if (!tdp_mmu_set_spte_atomic_no_dirty_log(kvm, iter, new_spte))
+ return false;
+
+ handle_changed_spte_dirty_log(kvm, iter->as_id, iter->gfn,
+ iter->old_spte, new_spte, iter->level);
+ return true;
+}
+
static inline bool tdp_mmu_zap_spte_atomic(struct kvm *kvm,
struct tdp_iter *iter)
{
@@ -1148,7 +1162,8 @@ static bool wrprot_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root,
for_each_tdp_pte_min_level(iter, root->spt, root->role.level,
min_level, start, end) {
- if (tdp_mmu_iter_cond_resched(kvm, &iter, false, false))
+retry:
+ if (tdp_mmu_iter_cond_resched(kvm, &iter, false, true))
continue;
if (!is_shadow_present_pte(iter.old_spte) ||
@@ -1158,7 +1173,15 @@ static bool wrprot_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root,
new_spte = iter.old_spte & ~PT_WRITABLE_MASK;
- tdp_mmu_set_spte_no_dirty_log(kvm, &iter, new_spte);
+ if (!tdp_mmu_set_spte_atomic_no_dirty_log(kvm, &iter,
+ new_spte)) {
+ /*
+ * 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;
}
@@ -1177,7 +1200,9 @@ bool kvm_tdp_mmu_wrprot_slot(struct kvm *kvm, struct kvm_memory_slot *slot,
struct kvm_mmu_page *root;
bool spte_set = false;
- for_each_tdp_mmu_root_yield_safe(kvm, root, slot->as_id, false)
+ lockdep_assert_held_read(&kvm->mmu_lock);
+
+ for_each_tdp_mmu_root_yield_safe(kvm, root, slot->as_id, true)
spte_set |= wrprot_gfn_range(kvm, root, slot->base_gfn,
slot->base_gfn + slot->npages, min_level);
@@ -1201,7 +1226,8 @@ static bool clear_dirty_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root,
rcu_read_lock();
tdp_root_for_each_leaf_pte(iter, root, start, end) {
- if (tdp_mmu_iter_cond_resched(kvm, &iter, false, false))
+retry:
+ if (tdp_mmu_iter_cond_resched(kvm, &iter, false, true))
continue;
if (spte_ad_need_write_protect(iter.old_spte)) {
@@ -1216,7 +1242,15 @@ static bool clear_dirty_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root,
continue;
}
- tdp_mmu_set_spte_no_dirty_log(kvm, &iter, new_spte);
+ if (!tdp_mmu_set_spte_atomic_no_dirty_log(kvm, &iter,
+ new_spte)) {
+ /*
+ * 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;
}
@@ -1236,7 +1270,9 @@ bool kvm_tdp_mmu_clear_dirty_slot(struct kvm *kvm, struct kvm_memory_slot *slot)
struct kvm_mmu_page *root;
bool spte_set = false;
- for_each_tdp_mmu_root_yield_safe(kvm, root, slot->as_id, false)
+ lockdep_assert_held_read(&kvm->mmu_lock);
+
+ for_each_tdp_mmu_root_yield_safe(kvm, root, slot->as_id, true)
spte_set |= clear_dirty_gfn_range(kvm, root, slot->base_gfn,
slot->base_gfn + slot->npages);
--
2.31.0.208.g409f899ff0-goog
next prev parent reply other threads:[~2021-04-01 23:38 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-01 23:37 [PATCH v2 00/13] More parallel operations for the TDP MMU Ben Gardon
2021-04-01 23:37 ` [PATCH v2 01/13] KVM: x86/mmu: Re-add const qualifier in kvm_tdp_mmu_zap_collapsible_sptes Ben Gardon
2021-05-26 21:25 ` Sean Christopherson
2021-04-01 23:37 ` [PATCH v2 02/13] KVM: x86/mmu: Move kvm_mmu_(get|put)_root to TDP MMU Ben Gardon
2021-04-01 23:37 ` [PATCH v2 03/13] KVM: x86/mmu: use tdp_mmu_free_sp to free roots Ben Gardon
2021-04-01 23:37 ` [PATCH v2 04/13] KVM: x86/mmu: Merge TDP MMU put and free root Ben Gardon
2021-04-01 23:37 ` [PATCH v2 05/13] KVM: x86/mmu: Refactor yield safe root iterator Ben Gardon
2021-04-01 23:37 ` [PATCH v2 06/13] KVM: x86/mmu: Make TDP MMU root refcount atomic Ben Gardon
2021-04-01 23:37 ` [PATCH v2 07/13] KVM: x86/mmu: handle cmpxchg failure in kvm_tdp_mmu_get_root Ben Gardon
2021-04-01 23:37 ` [PATCH v2 08/13] KVM: x86/mmu: Protect the tdp_mmu_roots list with RCU Ben Gardon
2021-04-01 23:37 ` [PATCH v2 09/13] KVM: x86/mmu: Allow zap gfn range to operate under the mmu read lock Ben Gardon
2021-04-02 7:53 ` Paolo Bonzini
2021-04-12 18:21 ` Ben Gardon
2021-04-01 23:37 ` [PATCH v2 10/13] KVM: x86/mmu: Allow zapping collapsible SPTEs to use MMU " Ben Gardon
2021-04-02 11:14 ` Paolo Bonzini
2021-04-01 23:37 ` Ben Gardon [this message]
2021-04-01 23:37 ` [PATCH v2 12/13] KVM: x86/mmu: Fast invalidation for TDP MMU Ben Gardon
2021-04-01 23:37 ` [PATCH v2 13/13] KVM: x86/mmu: Tear down roots in fast invalidation thread Ben Gardon
2021-04-02 11:43 ` [PATCH v2 00/13] More parallel operations for the TDP MMU Paolo Bonzini
2021-05-26 21:34 ` Sean Christopherson
2021-05-27 11:41 ` Paolo Bonzini
2021-05-27 15:26 ` Sean Christopherson
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