Re: [PATCH mm-unstable v1 1/5] mm/kvm: add mmu_notifier_test_clear_young()
From: Sean Christopherson <seanjc@google.com>
Date: 2023-02-23 17:14:24
Also in:
kvm, kvmarm, linux-arm-kernel, linux-mm, lkml
Subsystem:
kernel virtual machine (kvm), the rest · Maintainers:
Paolo Bonzini, Linus Torvalds
On Thu, Feb 16, 2023, Yu Zhao wrote:
quoted hunk ↗ jump to hunk
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 9c60384b5ae0..1b465df4a93d 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c@@ -875,6 +875,63 @@ static int kvm_mmu_notifier_clear_young(struct mmu_notifier *mn, return kvm_handle_hva_range_no_flush(mn, start, end, kvm_age_gfn); } +static bool kvm_test_clear_young(struct kvm *kvm, unsigned long start, + unsigned long end, unsigned long *bitmap) +{ + int i; + int key; + bool success = true; + + trace_kvm_age_hva(start, end); + + key = srcu_read_lock(&kvm->srcu); + + for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) { + struct interval_tree_node *node; + struct kvm_memslots *slots = __kvm_memslots(kvm, i); + + kvm_for_each_memslot_in_hva_range(node, slots, start, end - 1) { + gfn_t lsb_gfn; + unsigned long hva_start, hva_end; + struct kvm_gfn_range range = { + .slot = container_of(node, struct kvm_memory_slot, + hva_node[slots->node_idx]), + }; + + hva_start = max(start, range.slot->userspace_addr); + hva_end = min(end - 1, range.slot->userspace_addr + + range.slot->npages * PAGE_SIZE - 1); + + range.start = hva_to_gfn_memslot(hva_start, range.slot); + range.end = hva_to_gfn_memslot(hva_end, range.slot) + 1; + + if (WARN_ON_ONCE(range.end <= range.start)) + continue;
Extend __kvm_handle_hva_range() instead of copy-pasting. At a very quick glance, I believe all that is needed is (minus sanity checks):
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index d255964ec331..3296ae2cf6fa 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c@@ -544,6 +544,7 @@ struct kvm_hva_range { hva_handler_t handler; on_lock_fn_t on_lock; on_unlock_fn_t on_unlock; + bool lockless; bool flush_on_ret; bool may_block; };
@@ -616,7 +617,7 @@ static __always_inline int __kvm_handle_hva_range(struct kvm *kvm, gfn_range.end = hva_to_gfn_memslot(hva_end + PAGE_SIZE - 1, slot); gfn_range.slot = slot; - if (!locked) { + if (!range->lockless && !locked) { locked = true; KVM_MMU_LOCK(kvm); if (!IS_KVM_NULL_FN(range->on_lock))
+ + /* see the comments on the generic kvm_arch_has_test_clear_young() */ + lsb_gfn = hva_to_gfn_memslot(end - 1, range.slot); + + success = kvm_arch_test_clear_young(kvm, &range, lsb_gfn, bitmap); + if (!success) + break; + } + } + + srcu_read_unlock(&kvm->srcu, key); + + return success; +}