From: Quentin Perret <qperret@google.com>
To: maz@kernel.org, will@kernel.org, james.morse@arm.com,
alexandru.elisei@arm.com, catalin.marinas@arm.com,
suzuki.poulose@arm.com
Cc: linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, kernel-team@android.com,
linux-kernel@vger.kernel.org
Subject: [PATCH v2 7/7] KVM: arm64: Use less bits for hyp_page refcount
Date: Wed, 2 Jun 2021 09:43:47 +0000 [thread overview]
Message-ID: <20210602094347.3730846-8-qperret@google.com> (raw)
In-Reply-To: <20210602094347.3730846-1-qperret@google.com>
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: Quentin Perret <qperret@google.com>
---
arch/arm64/kvm/hyp/include/nvhe/memory.h | 2 +-
arch/arm64/kvm/hyp/nvhe/page_alloc.c | 1 +
2 files changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/kvm/hyp/include/nvhe/memory.h b/arch/arm64/kvm/hyp/include/nvhe/memory.h
index 3fe34fa30ea4..592b7edb3edb 100644
--- a/arch/arm64/kvm/hyp/include/nvhe/memory.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/memory.h
@@ -8,7 +8,7 @@
#include <linux/types.h>
struct hyp_page {
- unsigned int refcount;
+ unsigned short refcount;
unsigned short order;
};
diff --git a/arch/arm64/kvm/hyp/nvhe/page_alloc.c b/arch/arm64/kvm/hyp/nvhe/page_alloc.c
index be07055bbc10..41fc25bdfb34 100644
--- a/arch/arm64/kvm/hyp/nvhe/page_alloc.c
+++ b/arch/arm64/kvm/hyp/nvhe/page_alloc.c
@@ -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++;
}
--
2.32.0.rc0.204.g9fa02ecfa5-goog
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prev parent reply other threads:[~2021-06-02 9:47 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-02 9:43 [PATCH v2 0/7] KVM: arm64: Reduce hyp_vmemmap overhead Quentin Perret
2021-06-02 9:43 ` [PATCH v2 1/7] KVM: arm64: Move hyp_pool locking out of refcount helpers Quentin Perret
2021-06-02 9:43 ` [PATCH v2 2/7] KVM: arm64: Use refcount at hyp to check page availability Quentin Perret
2021-06-02 9:43 ` [PATCH v2 3/7] KVM: arm64: Remove list_head from hyp_page Quentin Perret
2021-06-02 9:43 ` [PATCH v2 4/7] KVM: arm64: Unify MMIO and mem host stage-2 pools Quentin Perret
2021-06-06 10:31 ` Marc Zyngier
2021-06-07 8:04 ` Quentin Perret
2021-06-02 9:43 ` [PATCH v2 5/7] KVM: arm64: Remove hyp_pool pointer from struct hyp_page Quentin Perret
2021-06-02 9:43 ` [PATCH v2 6/7] KVM: arm64: Use less bits for hyp_page order Quentin Perret
2021-06-02 9:43 ` Quentin Perret [this message]
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