diff mbox series

[BACKPORT,6.6.y] Fix mmu notifiers for range-based invalidates

Message ID 20250411172804.6014-1-will@kernel.org (mailing list archive)
State New
Headers show
Series [BACKPORT,6.6.y] Fix mmu notifiers for range-based invalidates | expand

Commit Message

Will Deacon April 11, 2025, 5:28 p.m. UTC 
From: Piotr Jaroszynski <pjaroszynski@nvidia.com>

[ Upstream commit f7edb07ad7c66eab3dce57384f33b9799d579133 ]

Update the __flush_tlb_range_op macro not to modify its parameters as
these are unexepcted semantics. In practice, this fixes the call to
mmu_notifier_arch_invalidate_secondary_tlbs() in
__flush_tlb_range_nosync() to use the correct range instead of an empty
range with start=end. The empty range was (un)lucky as it results in
taking the invalidate-all path that doesn't cause correctness issues,
but can certainly result in suboptimal perf.

This has been broken since commit 6bbd42e2df8f ("mmu_notifiers: call
invalidate_range() when invalidating TLBs") when the call to the
notifiers was added to __flush_tlb_range(). It predates the addition of
the __flush_tlb_range_op() macro from commit 360839027a6e ("arm64: tlb:
Refactor the core flush algorithm of __flush_tlb_range") that made the
bug hard to spot.

Fixes: 6bbd42e2df8f ("mmu_notifiers: call invalidate_range() when invalidating TLBs")

Signed-off-by: Piotr Jaroszynski <pjaroszynski@nvidia.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Raghavendra Rao Ananta <rananta@google.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Nicolin Chen <nicolinc@nvidia.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: iommu@lists.linux.dev
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
Cc: stable@vger.kernel.org # Backport for 6.6.y only
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Link: https://lore.kernel.org/r/20250304085127.2238030-1-pjaroszynski@nvidia.com
[will: Resolve conflicts due to lack of LPA2 support]
Signed-off-by: Will Deacon <will@kernel.org>
---
 arch/arm64/include/asm/tlbflush.h | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)
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Patch

diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
index b73baaf8ae47..d37db2f7a54c 100644
--- a/arch/arm64/include/asm/tlbflush.h
+++ b/arch/arm64/include/asm/tlbflush.h
@@ -369,31 +369,33 @@  static inline void arch_tlbbatch_flush(struct arch_tlbflush_unmap_batch *batch)
 #define __flush_tlb_range_op(op, start, pages, stride,			\
 				asid, tlb_level, tlbi_user)		\
 do {									\
+	typeof(start) __flush_start = start;				\
+	typeof(pages) __flush_pages = pages;				\
 	int num = 0;							\
 	int scale = 3;							\
 	unsigned long addr;						\
 									\
-	while (pages > 0) {						\
+	while (__flush_pages > 0) {					\
 		if (!system_supports_tlb_range() ||			\
-		    pages == 1) {					\
-			addr = __TLBI_VADDR(start, asid);		\
+		    __flush_pages == 1) {				\
+			addr = __TLBI_VADDR(__flush_start, asid);	\
 			__tlbi_level(op, addr, tlb_level);		\
 			if (tlbi_user)					\
 				__tlbi_user_level(op, addr, tlb_level);	\
-			start += stride;				\
-			pages -= stride >> PAGE_SHIFT;			\
+			__flush_start += stride;			\
+			__flush_pages -= stride >> PAGE_SHIFT;		\
 			continue;					\
 		}							\
 									\
-		num = __TLBI_RANGE_NUM(pages, scale);			\
+		num = __TLBI_RANGE_NUM(__flush_pages, scale);		\
 		if (num >= 0) {						\
-			addr = __TLBI_VADDR_RANGE(start, asid, scale,	\
-						  num, tlb_level);	\
+			addr = __TLBI_VADDR_RANGE(__flush_start, asid,	\
+						scale, num, tlb_level);	\
 			__tlbi(r##op, addr);				\
 			if (tlbi_user)					\
 				__tlbi_user(r##op, addr);		\
-			start += __TLBI_RANGE_PAGES(num, scale) << PAGE_SHIFT; \
-			pages -= __TLBI_RANGE_PAGES(num, scale);	\
+			__flush_start += __TLBI_RANGE_PAGES(num, scale) << PAGE_SHIFT; \
+			__flush_pages -= __TLBI_RANGE_PAGES(num, scale);\
 		}							\
 		scale--;						\
 	}								\