linux-kernel - [PATCH 2/2] KVM: arm64: Minor optimization of range_is

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Date:   Wed, 28 Jul 2021 15:32:32 +0000
From:   David Brazdil <dbrazdil@...gle.com>
To:     kvmarm@...ts.cs.columbia.edu
Cc:     Marc Zyngier <maz@...nel.org>, James Morse <james.morse@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Quentin Perret <qperret@...gle.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        David Brazdil <dbrazdil@...gle.com>
Subject: [PATCH 2/2] KVM: arm64: Minor optimization of range_is_memory

Currently range_is_memory finds the corresponding struct memblock_region
for both the lower and upper bounds of the given address range with two
rounds of binary search, and then checks that the two memblocks are the
same. Simplify this by only doing binary search on the lower bound and
then checking that the upper bound is in the same memblock.

Signed-off-by: David Brazdil <dbrazdil@...gle.com>
---
 arch/arm64/kvm/hyp/nvhe/mem_protect.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index a6ce991b1467..37d73af69634 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -189,13 +189,18 @@ static bool find_mem_range(phys_addr_t addr, struct kvm_mem_range *range)
 	return false;
 }
 
+static bool is_in_mem_range(phys_addr_t addr, struct kvm_mem_range *range)
+{
+	return range->start <= addr && addr < range->end;
+}
+
 static bool range_is_memory(u64 start, u64 end)
 {
-	struct kvm_mem_range r1, r2;
+	struct kvm_mem_range r;
 
-	if (!find_mem_range(start, &r1) || !find_mem_range(end - 1, &r2))
+	if (!find_mem_range(start, &r))
 		return false;
-	if (r1.start != r2.start)
+	if (!is_in_mem_range(end - 1, &r))
 		return false;
 
 	return true;
-- 
2.32.0.432.gabb21c7263-goog