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From: Christoph Hellwig <hch@lst.de>
To: Palmer Dabbelt <palmer@sifive.com>,
	Paul Walmsley <paul.walmsley@sifive.com>
Cc: Damien Le Moal <damien.lemoal@wdc.com>,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: [PATCH 07/15] riscv: implement remote sfence.i using IPIs
Date: Thu, 17 Oct 2019 19:37:35 +0200
Message-ID: <20191017173743.5430-8-hch@lst.de> (raw)
In-Reply-To: <20191017173743.5430-1-hch@lst.de>

The RISC-V ISA only supports flushing the instruction cache for the
local CPU core.  Currently we always offload the remote TLB flushing to
the SBI, which then issues an IPI under the hoods.  But with M-mode
we do not have an SBI so we have to do it ourselves.   IPI to the
other nodes using the existing kernel helpers instead if we have
native clint support and thus can IPI directly from the kernel.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/riscv/include/asm/sbi.h |  3 +++
 arch/riscv/mm/cacheflush.c   | 24 ++++++++++++++++++------
 2 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
index b167af3e7470..0cb74eccc73f 100644
--- a/arch/riscv/include/asm/sbi.h
+++ b/arch/riscv/include/asm/sbi.h
@@ -94,5 +94,8 @@ static inline void sbi_remote_sfence_vma_asid(const unsigned long *hart_mask,
 {
 	SBI_CALL_4(SBI_REMOTE_SFENCE_VMA_ASID, hart_mask, start, size, asid);
 }
+#else /* CONFIG_RISCV_SBI */
+/* stub to for code is only reachable under IS_ENABLED(CONFIG_RISCV_SBI): */
+void sbi_remote_fence_i(const unsigned long *hart_mask);
 #endif /* CONFIG_RISCV_SBI */
 #endif /* _ASM_RISCV_SBI_H */
diff --git a/arch/riscv/mm/cacheflush.c b/arch/riscv/mm/cacheflush.c
index 3f15938dec89..794c9ab256eb 100644
--- a/arch/riscv/mm/cacheflush.c
+++ b/arch/riscv/mm/cacheflush.c
@@ -10,9 +10,17 @@
 
 #include <asm/sbi.h>
 
+static void ipi_remote_fence_i(void *info)
+{
+	return local_flush_icache_all();
+}
+
 void flush_icache_all(void)
 {
-	sbi_remote_fence_i(NULL);
+	if (IS_ENABLED(CONFIG_RISCV_SBI))
+		sbi_remote_fence_i(NULL);
+	else
+		on_each_cpu(ipi_remote_fence_i, NULL, 1);
 }
 
 /*
@@ -28,7 +36,7 @@ void flush_icache_all(void)
 void flush_icache_mm(struct mm_struct *mm, bool local)
 {
 	unsigned int cpu;
-	cpumask_t others, hmask, *mask;
+	cpumask_t others, *mask;
 
 	preempt_disable();
 
@@ -46,10 +54,7 @@ void flush_icache_mm(struct mm_struct *mm, bool local)
 	 */
 	cpumask_andnot(&others, mm_cpumask(mm), cpumask_of(cpu));
 	local |= cpumask_empty(&others);
-	if (mm != current->active_mm || !local) {
-		riscv_cpuid_to_hartid_mask(&others, &hmask);
-		sbi_remote_fence_i(hmask.bits);
-	} else {
+	if (mm == current->active_mm && local) {
 		/*
 		 * It's assumed that at least one strongly ordered operation is
 		 * performed on this hart between setting a hart's cpumask bit
@@ -59,6 +64,13 @@ void flush_icache_mm(struct mm_struct *mm, bool local)
 		 * with flush_icache_deferred().
 		 */
 		smp_mb();
+	} else if (IS_ENABLED(CONFIG_RISCV_SBI)) {
+		cpumask_t hartid_mask;
+
+		riscv_cpuid_to_hartid_mask(&others, &hartid_mask);
+		sbi_remote_fence_i(cpumask_bits(&hartid_mask));
+	} else {
+		on_each_cpu_mask(&others, ipi_remote_fence_i, NULL, 1);
 	}
 
 	preempt_enable();
-- 
2.20.1


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  parent reply index

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-17 17:37 RISC-V nommu support v5 Christoph Hellwig
2019-10-17 17:37 ` [PATCH 01/15] riscv: cleanup <asm/bug.h> Christoph Hellwig
2019-10-18  2:50   ` Anup Patel
2019-10-23 22:04   ` Paul Walmsley
2019-10-17 17:37 ` [PATCH 02/15] riscv: cleanup do_trap_break Christoph Hellwig
2019-10-18  2:51   ` Anup Patel
2019-10-23 22:05   ` Paul Walmsley
2019-10-17 17:37 ` [PATCH 03/15] riscv: abstract out CSR names for supervisor vs machine mode Christoph Hellwig
2019-10-18  2:51   ` Anup Patel
2019-10-18 23:55   ` Paul Walmsley
2019-10-28  8:12     ` Christoph Hellwig
2019-10-17 17:37 ` [PATCH 04/15] riscv: don't allow selecting SBI based drivers for M-mode Christoph Hellwig
2019-10-18  2:52   ` Anup Patel
2019-10-17 17:37 ` [PATCH 05/15] riscv: poison SBI calls " Christoph Hellwig
2019-10-18  2:53   ` Anup Patel
2019-10-17 17:37 ` [PATCH 06/15] riscv: cleanup the default power off implementation Christoph Hellwig
2019-10-18  2:53   ` Anup Patel
2019-10-17 17:37 ` Christoph Hellwig [this message]
2019-10-18  2:55   ` [PATCH 07/15] riscv: implement remote sfence.i using IPIs Anup Patel
2019-10-17 17:37 ` [PATCH 08/15] riscv: add support for MMIO access to the timer registers Christoph Hellwig
2019-10-18  2:57   ` Anup Patel
2019-10-17 17:37 ` [PATCH 09/15] riscv: provide native clint access for M-mode Christoph Hellwig
2019-10-18  3:00   ` Anup Patel
2019-11-14  7:39   ` Paul Walmsley
2019-10-17 17:37 ` [PATCH 10/15] riscv: read the hart ID from mhartid on boot Christoph Hellwig
2019-10-18  3:01   ` Anup Patel
2019-11-14  7:40   ` Paul Walmsley
2019-10-17 17:37 ` [PATCH 11/15] riscv: use the correct interrupt levels for M-mode Christoph Hellwig
2019-10-18  3:01   ` Anup Patel
2019-10-17 17:37 ` [PATCH 12/15] riscv: clear the instruction cache and all registers when booting Christoph Hellwig
2019-10-18  3:05   ` Anup Patel
2019-10-17 17:37 ` [PATCH 13/15] riscv: add nommu support Christoph Hellwig
2019-10-18  3:04   ` Anup Patel
2019-10-17 17:37 ` [PATCH 14/15] riscv: provide a flat image loader Christoph Hellwig
2019-10-18  3:06   ` Anup Patel
2019-10-17 17:37 ` [PATCH 15/15] riscv: disable the EFI PECOFF header for M-mode Christoph Hellwig
2019-10-18  3:06   ` Anup Patel
2019-10-18  3:08 ` RISC-V nommu support v5 Anup Patel
2019-10-18  3:29   ` Paul Walmsley
2019-10-18 15:25     ` Christoph Hellwig
2019-10-18 23:46       ` Paul Walmsley

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