[PATCH v2 2/7] KVM: arm64: Use refcount at hyp to check page availability
From: Quentin Perret <hidden>
Date: 2021-06-02 09:44:04
Also in:
kvmarm, lkml
Subsystem:
arm64 port (aarch64 architecture), kernel virtual machine for arm64 (kvm/arm64), the rest · Maintainers:
Catalin Marinas, Will Deacon, Marc Zyngier, Oliver Upton, Linus Torvalds
The hyp buddy allocator currently checks the struct hyp_page list node to see if a page is available for allocation or not when trying to coalesce memory. Now that decrementing the refcount and attaching to the buddy tree is done in the same critical section, we can rely on the refcount of the buddy page to be in sync, which allows to replace the list node check by a refcount check. This will ease removing the list node from struct hyp_page later on. Signed-off-by: Quentin Perret <redacted> --- arch/arm64/kvm/hyp/nvhe/page_alloc.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/arch/arm64/kvm/hyp/nvhe/page_alloc.c b/arch/arm64/kvm/hyp/nvhe/page_alloc.c
index d666f4789e31..2602577daa00 100644
--- a/arch/arm64/kvm/hyp/nvhe/page_alloc.c
+++ b/arch/arm64/kvm/hyp/nvhe/page_alloc.c@@ -55,7 +55,7 @@ static struct hyp_page *__find_buddy_avail(struct hyp_pool *pool, { struct hyp_page *buddy = __find_buddy_nocheck(pool, p, order); - if (!buddy || buddy->order != order || list_empty(&buddy->node)) + if (!buddy || buddy->order != order || buddy->refcount) return NULL; return buddy;
@@ -133,6 +133,12 @@ static inline void hyp_set_page_refcounted(struct hyp_page *p) p->refcount = 1; } +static void __hyp_put_page(struct hyp_pool *pool, struct hyp_page *p) +{ + if (hyp_page_ref_dec_and_test(p)) + __hyp_attach_page(pool, p); +} + /* * Changes to the buddy tree and page refcounts must be done with the hyp_pool * lock held. If a refcount change requires an update to the buddy tree (e.g.
@@ -146,8 +152,7 @@ void hyp_put_page(void *addr) struct hyp_pool *pool = hyp_page_to_pool(p); hyp_spin_lock(&pool->lock); - if (hyp_page_ref_dec_and_test(p)) - __hyp_attach_page(pool, p); + __hyp_put_page(pool, p); hyp_spin_unlock(&pool->lock); }
@@ -202,15 +207,16 @@ int hyp_pool_init(struct hyp_pool *pool, u64 pfn, unsigned int nr_pages, /* Init the vmemmap portion */ p = hyp_phys_to_page(phys); - memset(p, 0, sizeof(*p) * nr_pages); for (i = 0; i < nr_pages; i++) { p[i].pool = pool; + p[i].order = 0; INIT_LIST_HEAD(&p[i].node); + hyp_set_page_refcounted(&p[i]); } /* Attach the unused pages to the buddy tree */ for (i = reserved_pages; i < nr_pages; i++) - __hyp_attach_page(pool, &p[i]); + __hyp_put_page(pool, &p[i]); return 0; }
--
2.32.0.rc0.204.g9fa02ecfa5-goog
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