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riscv: mm: still create swiotlb buffer for kmalloc() bouncing if required

PATCH Superseded Jisheng Zhang 2 participants 3 messages Nov 26, 2023 – Nov 27, 2023 RISC-V

v1 of 3 Superseded Latest is v3 →

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Jisheng Zhang

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#0 lore raw

PATCH 1/1 riscv: mm: still create swiotlb buffer for kmalloc() bouncing if required

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 <[email protected]>
---
 arch/riscv/mm/init.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)
arch/riscv/mm/init.c +15 -1
index 2e011cbddf3a..cbcb9918f721 100644
@@ -162,11 +162,25 @@ 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();
Signature · 1 line
2.42.0
build bot
#1 lore raw
kernel test robot noticed the following build errors:

Hi Jisheng,

kernel test robot noticed the following build errors:

[auto build test ERROR on linus/master]
[also build test ERROR on v6.7-rc2 next-20231124]
[If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Jisheng-Zhang/riscv-mm-still-create-swiotlb-buffer-for-kmalloc-bouncing-if-required/20231127-014531
base:   linus/master
patch link:    https://lore.kernel.org/r/20231126162528.2411-1-jszhang%40kernel.org
patch subject: [PATCH] riscv: mm: still create swiotlb buffer for kmalloc() bouncing if required
config: riscv-allnoconfig (https://download.01.org/0day-ci/archive/20231127/[email protected]/config)
compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project.git 4a5ac14ee968ff0ad5d2cc1ffa0299048db4c88a)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231127/[email protected]/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <[email protected]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/

All errors (new ones prefixed by >>):

>> arch/riscv/mm/init.c:171:6: error: use of undeclared identifier 'dma_cache_alignment'; did you mean 'dma_get_cache_alignment'?
     171 |             dma_cache_alignment != 1) {
         |             ^~~~~~~~~~~~~~~~~~~
         |             dma_get_cache_alignment

include/linux/dma-mapping.h:541:19: note: 'dma_get_cache_alignment' declared here
541 | static inline int dma_get_cache_alignment(void)
| ^
1 error generated.

vim +171 arch/riscv/mm/init.c

169
170 if (IS_ENABLED(CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC) && !swiotlb &&

 > 171		    dma_cache_alignment != 1) {

172 /*
173 * If no bouncing needed for ZONE_DMA, allocate 1MB swiotlb
174 * buffer per 1GB of RAM for kmalloc() bouncing on
175 * non-coherent platforms.
176 */
177 unsigned long size =
178 DIV_ROUND_UP(memblock_phys_mem_size(), 1024);
179 swiotlb_adjust_size(min(swiotlb_size_or_default(), size));
180 swiotlb = true;
181 }
182
183 swiotlb_init(swiotlb, SWIOTLB_VERBOSE);
184 memblock_free_all();
185
186 print_vm_layout();
187 }
188

Signature · 2 lines
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
build bot
#2 lore raw
In reply to Jisheng Zhang
kernel test robot noticed the following build errors:

Hi Jisheng,

kernel test robot noticed the following build errors:

[auto build test ERROR on linus/master]
[also build test ERROR on v6.7-rc3 next-20231127]
[If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Jisheng-Zhang/riscv-mm-still-create-swiotlb-buffer-for-kmalloc-bouncing-if-required/20231127-014531
base:   linus/master
patch link:    https://lore.kernel.org/r/20231126162528.2411-1-jszhang%40kernel.org
patch subject: [PATCH] riscv: mm: still create swiotlb buffer for kmalloc() bouncing if required
config: riscv-randconfig-002-20231127 (https://download.01.org/0day-ci/archive/20231127/[email protected]/config)
compiler: riscv64-linux-gcc (GCC) 13.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231127/[email protected]/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <[email protected]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/

All errors (new ones prefixed by >>):

arch/riscv/mm/init.c: In function 'mem_init':

>> arch/riscv/mm/init.c:171:13: error: 'dma_cache_alignment' undeclared (first use in this function); did you mean 'dma_get_cache_alignment'?
     171 |             dma_cache_alignment != 1) {
         |             ^~~~~~~~~~~~~~~~~~~
         |             dma_get_cache_alignment

arch/riscv/mm/init.c:171:13: note: each undeclared identifier is reported only once for each function it appears in

vim +171 arch/riscv/mm/init.c

169
170 if (IS_ENABLED(CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC) && !swiotlb &&

 > 171		    dma_cache_alignment != 1) {

172 /*
173 * If no bouncing needed for ZONE_DMA, allocate 1MB swiotlb
174 * buffer per 1GB of RAM for kmalloc() bouncing on
175 * non-coherent platforms.
176 */
177 unsigned long size =
178 DIV_ROUND_UP(memblock_phys_mem_size(), 1024);
179 swiotlb_adjust_size(min(swiotlb_size_or_default(), size));
180 swiotlb = true;
181 }
182
183 swiotlb_init(swiotlb, SWIOTLB_VERBOSE);
184 memblock_free_all();
185
186 print_vm_layout();
187 }
188

Signature · 2 lines
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki