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Message-Id: <20240701095505.165383-9-steven.price@arm.com>
Date: Mon, 1 Jul 2024 10:54:58 +0100
From: Steven Price <steven.price@....com>
To: kvm@...r.kernel.org,
kvmarm@...ts.linux.dev
Cc: Steven Price <steven.price@....com>,
Catalin Marinas <catalin.marinas@....com>,
Marc Zyngier <maz@...nel.org>,
Will Deacon <will@...nel.org>,
James Morse <james.morse@....com>,
Oliver Upton <oliver.upton@...ux.dev>,
Suzuki K Poulose <suzuki.poulose@....com>,
Zenghui Yu <yuzenghui@...wei.com>,
linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org,
Joey Gouly <joey.gouly@....com>,
Alexandru Elisei <alexandru.elisei@....com>,
Christoffer Dall <christoffer.dall@....com>,
Fuad Tabba <tabba@...gle.com>,
linux-coco@...ts.linux.dev,
Ganapatrao Kulkarni <gankulkarni@...amperecomputing.com>
Subject: [PATCH v4 08/15] arm64: mm: Avoid TLBI when marking pages as valid
When __change_memory_common() is purely setting the valid bit on a PTE
(e.g. via the set_memory_valid() call) there is no need for a TLBI as
either the entry isn't changing (the valid bit was already set) or the
entry was invalid and so should not have been cached in the TLB.
Signed-off-by: Steven Price <steven.price@....com>
---
v4: New patch
---
arch/arm64/mm/pageattr.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c
index 0e270a1c51e6..547a9e0b46c2 100644
--- a/arch/arm64/mm/pageattr.c
+++ b/arch/arm64/mm/pageattr.c
@@ -60,7 +60,13 @@ static int __change_memory_common(unsigned long start, unsigned long size,
ret = apply_to_page_range(&init_mm, start, size, change_page_range,
&data);
- flush_tlb_kernel_range(start, start + size);
+ /*
+ * If the memory is being made valid without changing any other bits
+ * then a TLBI isn't required as a non-valid entry cannot be cached in
+ * the TLB.
+ */
+ if (pgprot_val(set_mask) != PTE_VALID || pgprot_val(clear_mask))
+ flush_tlb_kernel_range(start, start + size);
return ret;
}
--
2.34.1
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