Commit 6929586d authored by Quentin Perret's avatar Quentin Perret Committed by Marc Zyngier
Browse files

KVM: arm64: Use less bits for hyp_page refcount 



The hyp_page refcount is currently encoded on 4 bytes even though we
never need to count that many objects in a page. Make it 2 bytes to save
some space in the vmemmap.

As overflows are more likely to happen as well, make sure to catch those
with a BUG in the increment function.

Signed-off-by: default avatarQuentin Perret <qperret@google.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210608114518.748712-8-qperret@google.com
parent 87ec0606

arch/arm64/kvm/hyp/include/nvhe/memory.h

+1 −1
Original line number Diff line number Diff line
@@ -8,7 +8,7 @@ 
#include <linux/types.h>



struct hyp_page {

	unsigned int refcount;

	unsigned short refcount;

	unsigned short order;

};

arch/arm64/kvm/hyp/nvhe/page_alloc.c

+1 −0
Original line number Diff line number Diff line
@@ -146,6 +146,7 @@ static struct hyp_page *__hyp_extract_page(struct hyp_pool *pool, 


static inline void hyp_page_ref_inc(struct hyp_page *p)

{

	BUG_ON(p->refcount == USHRT_MAX);

	p->refcount++;

}