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Message-ID: <Y/ee1s3XPGa62SFV@google.com>
Date: Thu, 23 Feb 2023 09:13:58 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Yu Zhao <yuzhao@...gle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Paolo Bonzini <pbonzini@...hat.com>,
Jonathan Corbet <corbet@....net>,
Michael Larabel <michael@...haellarabel.com>,
kvmarm@...ts.linux.dev, kvm@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
linux-mm@...ck.org, linuxppc-dev@...ts.ozlabs.org, x86@...nel.org,
linux-mm@...gle.com
Subject: Re: [PATCH mm-unstable v1 1/5] mm/kvm: add mmu_notifier_test_clear_young()
On Thu, Feb 16, 2023, Yu Zhao wrote:
> 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;
> +}
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