linux-kernel - [PATCH v6 11/18] arm64/mm: Split __flush_tlb

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Message-Id: <20240215103205.2607016-12-ryan.roberts@arm.com>
Date: Thu, 15 Feb 2024 10:31:58 +0000
From: Ryan Roberts <ryan.roberts@....com>
To: Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>,
	Ard Biesheuvel <ardb@...nel.org>,
	Marc Zyngier <maz@...nel.org>,
	James Morse <james.morse@....com>,
	Andrey Ryabinin <ryabinin.a.a@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Matthew Wilcox <willy@...radead.org>,
	Mark Rutland <mark.rutland@....com>,
	David Hildenbrand <david@...hat.com>,
	Kefeng Wang <wangkefeng.wang@...wei.com>,
	John Hubbard <jhubbard@...dia.com>,
	Zi Yan <ziy@...dia.com>,
	Barry Song <21cnbao@...il.com>,
	Alistair Popple <apopple@...dia.com>,
	Yang Shi <shy828301@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...or.com>
Cc: Ryan Roberts <ryan.roberts@....com>,
	linux-arm-kernel@...ts.infradead.org,
	x86@...nel.org,
	linuxppc-dev@...ts.ozlabs.org,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v6 11/18] arm64/mm: Split __flush_tlb_range() to elide trailing DSB

Split __flush_tlb_range() into __flush_tlb_range_nosync() +
__flush_tlb_range(), in the same way as the existing flush_tlb_page()
arrangement. This allows calling __flush_tlb_range_nosync() to elide the
trailing DSB. Forthcoming "contpte" code will take advantage of this
when clearing the young bit from a contiguous range of ptes.

Ordering between dsb and mmu_notifier_arch_invalidate_secondary_tlbs()
has changed, but now aligns with the ordering of __flush_tlb_page(). It
has been discussed that __flush_tlb_page() may be wrong though.
Regardless, both will be resolved separately if needed.

Reviewed-by: David Hildenbrand <david@...hat.com>
Tested-by: John Hubbard <jhubbard@...dia.com>
Signed-off-by: Ryan Roberts <ryan.roberts@....com>
---
 arch/arm64/include/asm/tlbflush.h | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
index 1deb5d789c2e..3b0e8248e1a4 100644
--- a/arch/arm64/include/asm/tlbflush.h
+++ b/arch/arm64/include/asm/tlbflush.h
@@ -422,7 +422,7 @@ do {									\
 #define __flush_s2_tlb_range_op(op, start, pages, stride, tlb_level) \
 	__flush_tlb_range_op(op, start, pages, stride, 0, tlb_level, false, kvm_lpa2_is_enabled());
 
-static inline void __flush_tlb_range(struct vm_area_struct *vma,
+static inline void __flush_tlb_range_nosync(struct vm_area_struct *vma,
 				     unsigned long start, unsigned long end,
 				     unsigned long stride, bool last_level,
 				     int tlb_level)
@@ -456,10 +456,19 @@ static inline void __flush_tlb_range(struct vm_area_struct *vma,
 		__flush_tlb_range_op(vae1is, start, pages, stride, asid,
 				     tlb_level, true, lpa2_is_enabled());
 
-	dsb(ish);
 	mmu_notifier_arch_invalidate_secondary_tlbs(vma->vm_mm, start, end);
 }
 
+static inline void __flush_tlb_range(struct vm_area_struct *vma,
+				     unsigned long start, unsigned long end,
+				     unsigned long stride, bool last_level,
+				     int tlb_level)
+{
+	__flush_tlb_range_nosync(vma, start, end, stride,
+				 last_level, tlb_level);
+	dsb(ish);
+}
+
 static inline void flush_tlb_range(struct vm_area_struct *vma,
 				   unsigned long start, unsigned long end)
 {
-- 
2.25.1