On Sun, Jun 05, 2022, Lai Jiangshan wrote:
> From: Lai Jiangshan <jiangshan.ljs@xxxxxxxxxxxx>
>
> mmu_unsync_walk() and __mmu_unsync_walk() requires the caller to clear
> unsync for the shadow pages in the resulted pvec by synching them or
> zapping them.
>
> All callers does so.
>
> Otherwise mmu_unsync_walk() and __mmu_unsync_walk() can't work because
> they always walk from the beginning.
>
> And mmu_unsync_walk() and __mmu_unsync_walk() directly clear unsync bits
> now, rename it.
What about mmu_gather_unsync_shadow_pages()? I agree that "walk" isn't a great
name, but IMO that's true regardless of when it updates the unsync bitmap. And
similar to a previous complaint about "clear" being ambiguous, I don't think it's
realistic that we'll be able to come up with a name the precisely and unambiguously
describes what exactly is being cleared.
Instead, regardless of what name we settle on, add a function comment. Probably
in the patch that changes the clear_unsync_child_bit behavior. That's a better
place to document the implementation detail.
> Signed-off-by: Lai Jiangshan <jiangshan.ljs@xxxxxxxxxxxx>
> ---
> arch/x86/kvm/mmu/mmu.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index 2446ede0b7b9..a56d328365e4 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -1773,7 +1773,7 @@ static inline void clear_unsync_child_bit(struct kvm_mmu_page *sp, int idx)
> __clear_bit(idx, sp->unsync_child_bitmap);
> }
>
> -static int __mmu_unsync_walk(struct kvm_mmu_page *sp,
> +static int __mmu_unsync_walk_and_clear(struct kvm_mmu_page *sp,
> struct kvm_mmu_pages *pvec)
> {
> int i, ret, nr_unsync_leaf = 0;
> @@ -1793,7 +1793,7 @@ static int __mmu_unsync_walk(struct kvm_mmu_page *sp,
> if (mmu_pages_add(pvec, child, i))
> return -ENOSPC;
>
> - ret = __mmu_unsync_walk(child, pvec);
> + ret = __mmu_unsync_walk_and_clear(child, pvec);
> if (ret < 0)
> return ret;
> nr_unsync_leaf += ret;
> @@ -1818,7 +1818,7 @@ static int __mmu_unsync_walk(struct kvm_mmu_page *sp,
>
> #define INVALID_INDEX (-1)
>
> -static int mmu_unsync_walk(struct kvm_mmu_page *sp,
> +static int mmu_unsync_walk_and_clear(struct kvm_mmu_page *sp,
> struct kvm_mmu_pages *pvec)
Please align indentation.
> {
> pvec->nr = 0;
> @@ -1826,7 +1826,7 @@ static int mmu_unsync_walk(struct kvm_mmu_page *sp,
> return 0;
>
> mmu_pages_add(pvec, sp, INVALID_INDEX);
> - return __mmu_unsync_walk(sp, pvec);
> + return __mmu_unsync_walk_and_clear(sp, pvec);
> }
>
> static void kvm_mmu_page_clear_unsync(struct kvm *kvm, struct kvm_mmu_page *sp)
> @@ -1962,7 +1962,7 @@ static int mmu_sync_children(struct kvm_vcpu *vcpu,
> LIST_HEAD(invalid_list);
> bool flush = false;
>
> - while (mmu_unsync_walk(parent, &pages)) {
> + while (mmu_unsync_walk_and_clear(parent, &pages)) {
> bool protected = false;
>
> for_each_sp(pages, sp, parents, i)
> @@ -2279,7 +2279,7 @@ static int mmu_zap_unsync_children(struct kvm *kvm,
> if (parent->role.level == PG_LEVEL_4K)
> return 0;
>
> - while (mmu_unsync_walk(parent, &pages)) {
> + while (mmu_unsync_walk_and_clear(parent, &pages)) {
> struct kvm_mmu_page *sp;
>
> for_each_sp(pages, sp, parents, i) {
> --
> 2.19.1.6.gb485710b
>
