On Tue, 07 Mar 2023 03:45:54 +0000,
Ricardo Koller <ricarkol@xxxxxxxxxx> wrote:
>
> This is the arm64 counterpart of commit cb00a70bd4b7 ("KVM: x86/mmu:
> Split huge pages mapped by the TDP MMU during KVM_CLEAR_DIRTY_LOG"),
> which has the benefit of splitting the cost of splitting a memslot
> across multiple ioctls.
>
> Split huge pages on the range specified using KVM_CLEAR_DIRTY_LOG.
> And do not split when enabling dirty logging if
> KVM_DIRTY_LOG_INITIALLY_SET is set.
>
> Signed-off-by: Ricardo Koller <ricarkol@xxxxxxxxxx>
> ---
> arch/arm64/kvm/mmu.c | 15 ++++++++++++---
> 1 file changed, 12 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> index 910aea6bbd1e..d54223b5db97 100644
> --- a/arch/arm64/kvm/mmu.c
> +++ b/arch/arm64/kvm/mmu.c
> @@ -1089,8 +1089,8 @@ static void kvm_mmu_split_memory_region(struct kvm *kvm, int slot)
> * @mask: The mask of pages at offset 'gfn_offset' in this memory
> * slot to enable dirty logging on
> *
> - * Writes protect selected pages to enable dirty logging for them. Caller must
> - * acquire kvm->mmu_lock.
> + * Splits selected pages to PAGE_SIZE and then writes protect them to enable
> + * dirty logging for them. Caller must acquire kvm->mmu_lock.
The code does things in the opposite order...
> */
> void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
> struct kvm_memory_slot *slot,
> @@ -1103,6 +1103,13 @@ void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
> lockdep_assert_held_write(&kvm->mmu_lock);
>
> stage2_wp_range(&kvm->arch.mmu, start, end);
> +
> + /*
> + * If initially-all-set mode is not set, then huge-pages were already
> + * split when enabling dirty logging: no need to do it again.
> + */
> + if (kvm_dirty_log_manual_protect_and_init_set(kvm))
This contradicts the comment. Which one is correct?
> + kvm_mmu_split_huge_pages(kvm, start, end);
> }
>
> static void kvm_send_hwpoison_signal(unsigned long address, short lsb)
> @@ -1889,7 +1896,9 @@ void kvm_arch_commit_memory_region(struct kvm *kvm,
> * this when deleting, moving, disabling dirty logging, or
> * creating the memslot (a nop). Doing it for deletes makes
> * sure we don't leak memory, and there's no need to keep the
> - * cache around for any of the other cases.
> + * cache around for any of the other cases. Keeping the cache
> + * is useful for successive KVM_CLEAR_DIRTY_LOG calls, which is
> + * not handled in this function.
Where is it handled then?
> */
> kvm_mmu_free_memory_cache(&kvm->arch.mmu.split_page_cache);
> }
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
