linux-kernel - [PATCH 6/7] KVM: arm64: Use less bits for hyp

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Message-Id: <20210527125134.2116404-7-qperret@google.com>
Date:   Thu, 27 May 2021 12:51:33 +0000
From:   Quentin Perret <qperret@...gle.com>
To:     maz@...nel.org, will@...nel.org, james.morse@....com,
        alexandru.elisei@....com, catalin.marinas@....com,
        suzuki.poulose@....com
Cc:     linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        kernel-team@...roid.com, linux-kernel@...r.kernel.org
Subject: [PATCH 6/7] KVM: arm64: Use less bits for hyp_page order

The hyp_page order is currently encoded on 4 bytes even though it is
guaranteed to be smaller than this. Make it 2 bytes to reduce the hyp
vmemmap overhead.

Signed-off-by: Quentin Perret <qperret@...gle.com>
---
 arch/arm64/kvm/hyp/include/nvhe/gfp.h    |  6 +++---
 arch/arm64/kvm/hyp/include/nvhe/memory.h |  2 +-
 arch/arm64/kvm/hyp/nvhe/page_alloc.c     | 12 ++++++------
 3 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/arch/arm64/kvm/hyp/include/nvhe/gfp.h b/arch/arm64/kvm/hyp/include/nvhe/gfp.h
index 9ed374648364..d420e5c0845f 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/gfp.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/gfp.h
@@ -7,7 +7,7 @@
 #include <nvhe/memory.h>
 #include <nvhe/spinlock.h>
 
-#define HYP_NO_ORDER	UINT_MAX
+#define HYP_NO_ORDER	USHRT_MAX
 
 struct hyp_pool {
 	/*
@@ -19,7 +19,7 @@ struct hyp_pool {
 	struct list_head free_area[MAX_ORDER];
 	phys_addr_t range_start;
 	phys_addr_t range_end;
-	unsigned int max_order;
+	unsigned short max_order;
 };
 
 static inline void hyp_page_ref_inc(struct hyp_page *p)
@@ -41,7 +41,7 @@ static inline void hyp_set_page_refcounted(struct hyp_page *p)
 }
 
 /* Allocation */
-void *hyp_alloc_pages(struct hyp_pool *pool, unsigned int order);
+void *hyp_alloc_pages(struct hyp_pool *pool, unsigned short order);
 void hyp_get_page(void *addr, struct hyp_pool *pool);
 void hyp_put_page(void *addr, struct hyp_pool *pool);
 
diff --git a/arch/arm64/kvm/hyp/include/nvhe/memory.h b/arch/arm64/kvm/hyp/include/nvhe/memory.h
index 991636be2f46..3fe34fa30ea4 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/memory.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/memory.h
@@ -9,7 +9,7 @@
 
 struct hyp_page {
 	unsigned int refcount;
-	unsigned int order;
+	unsigned short order;
 };
 
 extern u64 __hyp_vmemmap;
diff --git a/arch/arm64/kvm/hyp/nvhe/page_alloc.c b/arch/arm64/kvm/hyp/nvhe/page_alloc.c
index e453108a2d95..2ba2c550ab03 100644
--- a/arch/arm64/kvm/hyp/nvhe/page_alloc.c
+++ b/arch/arm64/kvm/hyp/nvhe/page_alloc.c
@@ -32,7 +32,7 @@ u64 __hyp_vmemmap;
  */
 static struct hyp_page *__find_buddy_nocheck(struct hyp_pool *pool,
 					     struct hyp_page *p,
-					     unsigned int order)
+					     unsigned short order)
 {
 	phys_addr_t addr = hyp_page_to_phys(p);
 
@@ -51,7 +51,7 @@ static struct hyp_page *__find_buddy_nocheck(struct hyp_pool *pool,
 /* Find a buddy page currently available for allocation */
 static struct hyp_page *__find_buddy_avail(struct hyp_pool *pool,
 					   struct hyp_page *p,
-					   unsigned int order)
+					   unsigned short order)
 {
 	struct hyp_page *buddy = __find_buddy_nocheck(pool, p, order);
 
@@ -93,7 +93,7 @@ static inline struct hyp_page *node_to_page(struct list_head *node)
 static void __hyp_attach_page(struct hyp_pool *pool,
 			      struct hyp_page *p)
 {
-	unsigned int order = p->order;
+	unsigned short order = p->order;
 	struct hyp_page *buddy;
 
 	memset(hyp_page_to_virt(p), 0, PAGE_SIZE << p->order);
@@ -123,7 +123,7 @@ static void __hyp_attach_page(struct hyp_pool *pool,
 
 static struct hyp_page *__hyp_extract_page(struct hyp_pool *pool,
 					   struct hyp_page *p,
-					   unsigned int order)
+					   unsigned short order)
 {
 	struct hyp_page *buddy;
 
@@ -168,9 +168,9 @@ void hyp_get_page(void *addr, struct hyp_pool *pool)
 	hyp_spin_unlock(&pool->lock);
 }
 
-void *hyp_alloc_pages(struct hyp_pool *pool, unsigned int order)
+void *hyp_alloc_pages(struct hyp_pool *pool, unsigned short order)
 {
-	unsigned int i = order;
+	unsigned short i = order;
 	struct hyp_page *p;
 
 	hyp_spin_lock(&pool->lock);
-- 
2.31.1.818.g46aad6cb9e-goog