Messages in this thread Patch in this message | | | Date | Wed, 10 Nov 2021 14:29:55 -0800 | Subject | [RFC 04/19] KVM: x86/mmu: Yield while processing disconnected_sps | From | Ben Gardon <> |
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When preparing to free disconnected SPs, the list can accumulate many entries; enough that it is likely necessary to yeild while queuing RCU callbacks to free the SPs.
Signed-off-by: Ben Gardon <bgardon@google.com> --- arch/x86/kvm/mmu/tdp_mmu.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index a448f0f2d993..c2a9f7acf8ef 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -513,7 +513,8 @@ static void handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn, * being removed from the paging structure and this function being called. */ static void handle_disconnected_sps(struct kvm *kvm, - struct list_head *disconnected_sps) + struct list_head *disconnected_sps, + bool can_yield, bool shared) { struct kvm_mmu_page *sp; struct kvm_mmu_page *next; @@ -521,6 +522,16 @@ static void handle_disconnected_sps(struct kvm *kvm, list_for_each_entry_safe(sp, next, disconnected_sps, link) { list_del(&sp->link); call_rcu(&sp->rcu_head, tdp_mmu_free_sp_rcu_callback); + + if (can_yield && + (need_resched() || rwlock_needbreak(&kvm->mmu_lock))) { + rcu_read_unlock(); + if (shared) + cond_resched_rwlock_read(&kvm->mmu_lock); + else + cond_resched_rwlock_write(&kvm->mmu_lock); + rcu_read_lock(); + } } } @@ -599,7 +610,7 @@ static inline bool tdp_mmu_zap_spte_atomic(struct kvm *kvm, */ WRITE_ONCE(*rcu_dereference(iter->sptep), 0); - handle_disconnected_sps(kvm, &disconnected_sps); + handle_disconnected_sps(kvm, &disconnected_sps, false, true); return true; } @@ -817,7 +828,8 @@ static bool zap_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root, if (!list_empty(&disconnected_sps)) { kvm_flush_remote_tlbs(kvm); - handle_disconnected_sps(kvm, &disconnected_sps); + handle_disconnected_sps(kvm, &disconnected_sps, + can_yield, shared); flush = false; } -- 2.34.0.rc0.344.g81b53c2807-goog
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