On Tue, Dec 06, 2022 at 05:35:56PM +0000, Ben Gardon wrote:
> In continuing to factor the rmap out of mmu.c, move the rmap_iterator
> and associated functions and macros into rmap.(c|h).
>
> No functional change intended.
>
> Signed-off-by: Ben Gardon <bgardon@xxxxxxxxxx>
> ---
> arch/x86/kvm/mmu/mmu.c | 76 -----------------------------------------
> arch/x86/kvm/mmu/rmap.c | 61 +++++++++++++++++++++++++++++++++
> arch/x86/kvm/mmu/rmap.h | 18 ++++++++++
> 3 files changed, 79 insertions(+), 76 deletions(-)
>
[...]
> diff --git a/arch/x86/kvm/mmu/rmap.h b/arch/x86/kvm/mmu/rmap.h
> index 059765b6e066..13b265f3a95e 100644
> --- a/arch/x86/kvm/mmu/rmap.h
> +++ b/arch/x86/kvm/mmu/rmap.h
> @@ -31,4 +31,22 @@ void free_pte_list_desc(struct pte_list_desc *pte_list_desc);
> void pte_list_remove(u64 *spte, struct kvm_rmap_head *rmap_head);
> unsigned int pte_list_count(struct kvm_rmap_head *rmap_head);
>
> +/*
> + * Used by the following functions to iterate through the sptes linked by a
> + * rmap. All fields are private and not assumed to be used outside.
> + */
> +struct rmap_iterator {
> + /* private fields */
> + struct pte_list_desc *desc; /* holds the sptep if not NULL */
> + int pos; /* index of the sptep */
> +};
> +
> +u64 *rmap_get_first(struct kvm_rmap_head *rmap_head,
> + struct rmap_iterator *iter);
> +u64 *rmap_get_next(struct rmap_iterator *iter);
> +
> +#define for_each_rmap_spte(_rmap_head_, _iter_, _spte_) \
> + for (_spte_ = rmap_get_first(_rmap_head_, _iter_); \
> + _spte_; _spte_ = rmap_get_next(_iter_))
> +
I always found these function names and kvm_rmap_head confusing since
they are about iterating through the pte_list_desc data structure. The
rmap (gfn -> list of sptes) is a specific application of the
pte_list_desc structure, but not the only application. There's also
parent_ptes in struct kvm_mmu_page, which is not an rmap, just a plain
old list of ptes.
While you are refactoring this code, what do you think about doing the
following renames?
struct kvm_rmap_head -> struct pte_list_head
struct rmap_iterator -> struct pte_list_iterator
rmap_get_first() -> pte_list_get_first()
rmap_get_next() -> pte_list_get_next()
for_each_rmap_spte() -> for_each_pte_list_entry()
Then we can reserve the term "rmap" just for the actual rmap
(slot->arch.rmap), and code that deals with sp->parent_ptes will become
a lot more clear IMO (because it will not longer mention rmap).
e.g. We go from this:
struct rmap_iterator iter;
u64 *sptep;
for_each_rmap_spte(&sp->parent_ptes, &iter, sptep) {
...
}
To this:
struct pte_list_iterator iter;
u64 *sptep;
for_each_pte_list_entry(&sp->parent_ptes, &iter, sptep) {
...
}
