在 2023/8/10 17:02, Yan Zhao 写道:
> Register to .numa_protect() callback in mmu notifier so that KVM can get
> acurate information about when a page is PROT_NONE protected in primary
> MMU and unmap it in secondary MMU accordingly.
>
> In KVM's .invalidate_range_start() handler, if the event is to notify that
> the range may be protected to PROT_NONE for NUMA migration purpose,
> don't do the unmapping in secondary MMU. Hold on until.numa_protect()
> comes.
>
> Signed-off-by: Yan Zhao <yan.y.zhao@xxxxxxxxx>
> ---
> virt/kvm/kvm_main.c | 25 ++++++++++++++++++++++---
> 1 file changed, 22 insertions(+), 3 deletions(-)
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index dfbaafbe3a00..907444a1761b 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -711,6 +711,20 @@ static void kvm_mmu_notifier_change_pte(struct mmu_notifier *mn,
> kvm_handle_hva_range(mn, address, address + 1, pte, kvm_change_spte_gfn);
> }
>
> +static void kvm_mmu_notifier_numa_protect(struct mmu_notifier *mn,
> + struct mm_struct *mm,
> + unsigned long start,
> + unsigned long end)
> +{
> + struct kvm *kvm = mmu_notifier_to_kvm(mn);
> +
> + WARN_ON_ONCE(!READ_ONCE(kvm->mn_active_invalidate_count));
> + if (!READ_ONCE(kvm->mmu_invalidate_in_progress))
> + return;
> +
> + kvm_handle_hva_range(mn, start, end, __pte(0), kvm_unmap_gfn_range);
> +}
numa balance will scan wide memory range, and there will be one time
ipi notification with kvm_flush_remote_tlbs. With page level notification,
it may bring out lots of flush remote tlb ipi notification.
however numa balance notification, pmd table of vm maybe needs not be freed
in kvm_unmap_gfn_range.
Regards
Bibo Mao
> +
> void kvm_mmu_invalidate_begin(struct kvm *kvm, unsigned long start,
> unsigned long end)
> {
> @@ -744,14 +758,18 @@ static int kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn,
> const struct mmu_notifier_range *range)
> {
> struct kvm *kvm = mmu_notifier_to_kvm(mn);
> + bool is_numa = (range->event == MMU_NOTIFY_PROTECTION_VMA) &&
> + (range->flags & MMU_NOTIFIER_RANGE_NUMA);
> const struct kvm_hva_range hva_range = {
> .start = range->start,
> .end = range->end,
> .pte = __pte(0),
> - .handler = kvm_unmap_gfn_range,
> + .handler = !is_numa ? kvm_unmap_gfn_range :
> + (void *)kvm_null_fn,
> .on_lock = kvm_mmu_invalidate_begin,
> - .on_unlock = kvm_arch_guest_memory_reclaimed,
> - .flush_on_ret = true,
> + .on_unlock = !is_numa ? kvm_arch_guest_memory_reclaimed :
> + (void *)kvm_null_fn,
> + .flush_on_ret = !is_numa ? true : false,
> .may_block = mmu_notifier_range_blockable(range),
> };
>
> @@ -899,6 +917,7 @@ static const struct mmu_notifier_ops kvm_mmu_notifier_ops = {
> .clear_young = kvm_mmu_notifier_clear_young,
> .test_young = kvm_mmu_notifier_test_young,
> .change_pte = kvm_mmu_notifier_change_pte,
> + .numa_protect = kvm_mmu_notifier_numa_protect,
> .release = kvm_mmu_notifier_release,
> };
>
