From: Jisheng Zhang <jszhang@kernel.org>
To: Paul Walmsley <paul.walmsley@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>
Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
Alexandre Ghiti <alexghiti@rivosinc.com>
Subject: [PATCH v3 RESEND] riscv: mm: still create swiotlb buffer for kmalloc() bouncing if required
Date: Mon, 25 Mar 2024 19:00:36 +0800 [thread overview]
Message-ID: <20240325110036.1564-1-jszhang@kernel.org> (raw)
After commit f51f7a0fc2f4 ("riscv: enable DMA_BOUNCE_UNALIGNED_KMALLOC
for !dma_coherent"), for non-coherent platforms with less than 4GB
memory, we rely on users to pass "swiotlb=mmnn,force" kernel parameters
to enable DMA bouncing for unaligned kmalloc() buffers. Now let's go
further: If no bouncing needed for ZONE_DMA, let kernel automatically
allocate 1MB swiotlb buffer per 1GB of RAM for kmalloc() bouncing on
non-coherent platforms, so that no need to pass "swiotlb=mmnn,force"
any more.
The math of "1MB swiotlb buffer per 1GB of RAM for kmalloc() bouncing"
is taken from arm64. Users can still force smaller swiotlb buffer by
passing "swiotlb=mmnn".
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
---
since v2:
- rebase on v6.8-rc1
- collect Reviewed-by tag
since v1
- fix build error if CONFIG_RISCV_DMA_NONCOHERENT=n
arch/riscv/include/asm/cache.h | 2 +-
arch/riscv/mm/init.c | 16 +++++++++++++++-
2 files changed, 16 insertions(+), 2 deletions(-)
diff --git a/arch/riscv/include/asm/cache.h b/arch/riscv/include/asm/cache.h
index 2174fe7bac9a..570e9d8acad1 100644
--- a/arch/riscv/include/asm/cache.h
+++ b/arch/riscv/include/asm/cache.h
@@ -26,8 +26,8 @@
#ifndef __ASSEMBLY__
-#ifdef CONFIG_RISCV_DMA_NONCOHERENT
extern int dma_cache_alignment;
+#ifdef CONFIG_RISCV_DMA_NONCOHERENT
#define dma_get_cache_alignment dma_get_cache_alignment
static inline int dma_get_cache_alignment(void)
{
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index fe8e159394d8..ac5e7f64c05c 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -161,11 +161,25 @@ static void print_vm_layout(void) { }
void __init mem_init(void)
{
+ bool swiotlb = max_pfn > PFN_DOWN(dma32_phys_limit);
#ifdef CONFIG_FLATMEM
BUG_ON(!mem_map);
#endif /* CONFIG_FLATMEM */
- swiotlb_init(max_pfn > PFN_DOWN(dma32_phys_limit), SWIOTLB_VERBOSE);
+ if (IS_ENABLED(CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC) && !swiotlb &&
+ dma_cache_alignment != 1) {
+ /*
+ * If no bouncing needed for ZONE_DMA, allocate 1MB swiotlb
+ * buffer per 1GB of RAM for kmalloc() bouncing on
+ * non-coherent platforms.
+ */
+ unsigned long size =
+ DIV_ROUND_UP(memblock_phys_mem_size(), 1024);
+ swiotlb_adjust_size(min(swiotlb_size_or_default(), size));
+ swiotlb = true;
+ }
+
+ swiotlb_init(swiotlb, SWIOTLB_VERBOSE);
memblock_free_all();
print_vm_layout();
--
2.43.0
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next reply other threads:[~2024-03-25 11:14 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-25 11:00 Jisheng Zhang [this message]
2024-04-28 22:00 ` [PATCH v3 RESEND] riscv: mm: still create swiotlb buffer for kmalloc() bouncing if required patchwork-bot+linux-riscv
2024-05-07 15:08 ` Geert Uytterhoeven
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