linux-kernel - [PATCH v5 07/13] riscv: Apply SiFive CIP-1200 workaround to single-ASID sfence.vma

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Date: Thu, 29 Feb 2024 15:21:48 -0800
From: Samuel Holland <samuel.holland@...ive.com>
To: Palmer Dabbelt <palmer@...belt.com>,
	linux-riscv@...ts.infradead.org
Cc: linux-kernel@...r.kernel.org,
	linux-mm@...ck.org,
	Alexandre Ghiti <alexghiti@...osinc.com>,
	Jisheng Zhang <jszhang@...nel.org>,
	Yunhui Cui <cuiyunhui@...edance.com>,
	Samuel Holland <samuel.holland@...ive.com>
Subject: [PATCH v5 07/13] riscv: Apply SiFive CIP-1200 workaround to single-ASID sfence.vma

commit 3f1e782998cd ("riscv: add ASID-based tlbflushing methods") added
calls to the sfence.vma instruction with rs2 != x0. These single-ASID
instruction variants are also affected by SiFive errata CIP-1200.

Until now, the errata workaround was not needed for the single-ASID
sfence.vma variants, because they were only used when the ASID allocator
was enabled, and the affected SiFive platforms do not support multiple
ASIDs. However, we are going to start using those sfence.vma variants
regardless of ASID support, so now we need alternatives covering them.

Signed-off-by: Samuel Holland <samuel.holland@...ive.com>
---

(no changes since v2)

Changes in v2:
 - Rebase on Alexandre's "riscv: tlb flush improvements" series v5

 arch/riscv/include/asm/errata_list.h | 12 +++++++++++-
 arch/riscv/include/asm/tlbflush.h    | 19 ++++++++++++++++++-
 arch/riscv/mm/tlbflush.c             | 23 -----------------------
 3 files changed, 29 insertions(+), 25 deletions(-)

diff --git a/arch/riscv/include/asm/errata_list.h b/arch/riscv/include/asm/errata_list.h
index ea33288f8a25..6e2762101968 100644
--- a/arch/riscv/include/asm/errata_list.h
+++ b/arch/riscv/include/asm/errata_list.h
@@ -43,11 +43,21 @@ ALTERNATIVE(__stringify(RISCV_PTR do_page_fault),			\
 	    CONFIG_ERRATA_SIFIVE_CIP_453)
 #else /* !__ASSEMBLY__ */
 
-#define ALT_FLUSH_TLB_PAGE(x)						\
+#define ALT_SFENCE_VMA_ASID(asid)					\
+asm(ALTERNATIVE("sfence.vma x0, %0", "sfence.vma", SIFIVE_VENDOR_ID,	\
+		ERRATA_SIFIVE_CIP_1200, CONFIG_ERRATA_SIFIVE_CIP_1200)	\
+		: : "r" (asid) : "memory")
+
+#define ALT_SFENCE_VMA_ADDR(addr)					\
 asm(ALTERNATIVE("sfence.vma %0", "sfence.vma", SIFIVE_VENDOR_ID,	\
 		ERRATA_SIFIVE_CIP_1200, CONFIG_ERRATA_SIFIVE_CIP_1200)	\
 		: : "r" (addr) : "memory")
 
+#define ALT_SFENCE_VMA_ADDR_ASID(addr, asid)				\
+asm(ALTERNATIVE("sfence.vma %0, %1", "sfence.vma", SIFIVE_VENDOR_ID,	\
+		ERRATA_SIFIVE_CIP_1200, CONFIG_ERRATA_SIFIVE_CIP_1200)	\
+		: : "r" (addr), "r" (asid) : "memory")
+
 /*
  * _val is marked as "will be overwritten", so need to set it to 0
  * in the default case.
diff --git a/arch/riscv/include/asm/tlbflush.h b/arch/riscv/include/asm/tlbflush.h
index 4f86424b1ba5..463b615d7728 100644
--- a/arch/riscv/include/asm/tlbflush.h
+++ b/arch/riscv/include/asm/tlbflush.h
@@ -22,10 +22,27 @@ static inline void local_flush_tlb_all(void)
 	__asm__ __volatile__ ("sfence.vma" : : : "memory");
 }
 
+static inline void local_flush_tlb_all_asid(unsigned long asid)
+{
+	if (asid != FLUSH_TLB_NO_ASID)
+		ALT_SFENCE_VMA_ASID(asid);
+	else
+		local_flush_tlb_all();
+}
+
 /* Flush one page from local TLB */
 static inline void local_flush_tlb_page(unsigned long addr)
 {
-	ALT_FLUSH_TLB_PAGE(__asm__ __volatile__ ("sfence.vma %0" : : "r" (addr) : "memory"));
+	ALT_SFENCE_VMA_ADDR(addr);
+}
+
+static inline void local_flush_tlb_page_asid(unsigned long addr,
+					     unsigned long asid)
+{
+	if (asid != FLUSH_TLB_NO_ASID)
+		ALT_SFENCE_VMA_ADDR_ASID(addr, asid);
+	else
+		local_flush_tlb_page(addr);
 }
 
 void flush_tlb_all(void);
diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c
index 69402c260a89..365e0a0e4725 100644
--- a/arch/riscv/mm/tlbflush.c
+++ b/arch/riscv/mm/tlbflush.c
@@ -7,29 +7,6 @@
 #include <asm/sbi.h>
 #include <asm/mmu_context.h>
 
-static inline void local_flush_tlb_all_asid(unsigned long asid)
-{
-	if (asid != FLUSH_TLB_NO_ASID)
-		__asm__ __volatile__ ("sfence.vma x0, %0"
-				:
-				: "r" (asid)
-				: "memory");
-	else
-		local_flush_tlb_all();
-}
-
-static inline void local_flush_tlb_page_asid(unsigned long addr,
-		unsigned long asid)
-{
-	if (asid != FLUSH_TLB_NO_ASID)
-		__asm__ __volatile__ ("sfence.vma %0, %1"
-				:
-				: "r" (addr), "r" (asid)
-				: "memory");
-	else
-		local_flush_tlb_page(addr);
-}
-
 /*
  * Flush entire TLB if number of entries to be flushed is greater
  * than the threshold below.
-- 
2.43.1