Re: [PATCH v5 2/3] iommu/io-pgtable-arm-v7s: Request DMA32 memory, and improve debugging
On 12/7/18 7:16 AM, Nicolas Boichat wrote:
> IOMMUs using ARMv7 short-descriptor format require page tables
> (level 1 and 2) to be allocated within the first 4GB of RAM, even
> on 64-bit systems.
>
> For level 1/2 pages, ensure GFP_DMA32 is used if CONFIG_ZONE_DMA32
> is defined (e.g. on arm64 platforms).
>
> For level 2 pages, allocate a slab cache in SLAB_CACHE_DMA32. Note
> that we do not explicitly pass GFP_DMA[32] to kmem_cache_zalloc,
> as this is not strictly necessary, and would cause a warning
> in mm/sl*b.c, as we did not update GFP_SLAB_BUG_MASK.
>
> Also, print an error when the physical address does not fit in
> 32-bit, to make debugging easier in the future.
>
> Fixes: ad67f5a6545f ("arm64: replace ZONE_DMA with ZONE_DMA32")
Also, CC stable?
> Signed-off-by: Nicolas Boichat
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Re: [PATCH v5 2/3] iommu/io-pgtable-arm-v7s: Request DMA32 memory, and improve debugging
On Fri, Dec 7, 2018 at 4:05 PM Matthew Wilcox wrote: > > On Fri, Dec 07, 2018 at 02:16:19PM +0800, Nicolas Boichat wrote: > > +#ifdef CONFIG_ZONE_DMA32 > > +#define ARM_V7S_TABLE_GFP_DMA GFP_DMA32 > > +#define ARM_V7S_TABLE_SLAB_CACHE SLAB_CACHE_DMA32 > > This name doesn't make any sense. Why not ARM_V7S_TABLE_SLAB_FLAGS ? Sure, will fix in v6 then. > > +#else > > +#define ARM_V7S_TABLE_GFP_DMA GFP_DMA > > +#define ARM_V7S_TABLE_SLAB_CACHE SLAB_CACHE_DMA > > Can you remind me again why it is, on machines which don't support > ZONE_DMA32, why we have to allocate from ZONE_DMA? My understanding > is that 64-bit machines have ZONE_DMA32 and 32-bit machines don't. > So shouldn't this rather be GFP_KERNEL? Sorry I mean to reply on the v4 thread, Christoph raised the same question (https://patchwork.kernel.org/patch/10713025/). I don't know, and I don't have all the hardware needed to test this ,-( Robin and Will both didn't seem sure. I'd rather not introduce a new regression, this patch series tries to fix a known arm64 regression, where we _need_ tables to be in DMA32. If we want to change 32-bit hardware to use GFP_KERNEL, and we're sure it works, that's fine by me, but it should be in another patch set. Hope this makes sense, Thanks, > Actually, maybe we could centralise this in gfp.h: > > #ifdef CONFIG_64BIT > # ifdef CONFIG_ZONE_DMA32 > #define GFP_32BIT GFP_DMA32 > # else > #define GFP_32BIT GFP_DMA > #else /* 32-bit */ > #define GFP_32BIT GFP_KERNEL > #endif > ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
Re: [PATCH v5 2/3] iommu/io-pgtable-arm-v7s: Request DMA32 memory, and improve debugging
On Fri, Dec 07, 2018 at 02:16:19PM +0800, Nicolas Boichat wrote: > +#ifdef CONFIG_ZONE_DMA32 > +#define ARM_V7S_TABLE_GFP_DMA GFP_DMA32 > +#define ARM_V7S_TABLE_SLAB_CACHE SLAB_CACHE_DMA32 This name doesn't make any sense. Why not ARM_V7S_TABLE_SLAB_FLAGS ? > +#else > +#define ARM_V7S_TABLE_GFP_DMA GFP_DMA > +#define ARM_V7S_TABLE_SLAB_CACHE SLAB_CACHE_DMA Can you remind me again why it is, on machines which don't support ZONE_DMA32, why we have to allocate from ZONE_DMA? My understanding is that 64-bit machines have ZONE_DMA32 and 32-bit machines don't. So shouldn't this rather be GFP_KERNEL? Actually, maybe we could centralise this in gfp.h: #ifdef CONFIG_64BIT # ifdef CONFIG_ZONE_DMA32 #define GFP_32BIT GFP_DMA32 # else #define GFP_32BIT GFP_DMA #else /* 32-bit */ #define GFP_32BIT GFP_KERNEL #endif ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
[PATCH v5 2/3] iommu/io-pgtable-arm-v7s: Request DMA32 memory, and improve debugging
IOMMUs using ARMv7 short-descriptor format require page tables
(level 1 and 2) to be allocated within the first 4GB of RAM, even
on 64-bit systems.
For level 1/2 pages, ensure GFP_DMA32 is used if CONFIG_ZONE_DMA32
is defined (e.g. on arm64 platforms).
For level 2 pages, allocate a slab cache in SLAB_CACHE_DMA32. Note
that we do not explicitly pass GFP_DMA[32] to kmem_cache_zalloc,
as this is not strictly necessary, and would cause a warning
in mm/sl*b.c, as we did not update GFP_SLAB_BUG_MASK.
Also, print an error when the physical address does not fit in
32-bit, to make debugging easier in the future.
Fixes: ad67f5a6545f ("arm64: replace ZONE_DMA with ZONE_DMA32")
Signed-off-by: Nicolas Boichat
---
Changes since v2:
- Commit message
(v3 used the page_frag approach)
Changes since v4:
- Do not pass ARM_V7S_TABLE_GFP_DMA to kmem_cache_zalloc, as this
is unnecessary, and would trigger a warning.
drivers/iommu/io-pgtable-arm-v7s.c | 19 +++
1 file changed, 15 insertions(+), 4 deletions(-)
diff --git a/drivers/iommu/io-pgtable-arm-v7s.c
b/drivers/iommu/io-pgtable-arm-v7s.c
index 445c3bde04800c..f311fe1dfa47b7 100644
--- a/drivers/iommu/io-pgtable-arm-v7s.c
+++ b/drivers/iommu/io-pgtable-arm-v7s.c
@@ -161,6 +161,14 @@
#define ARM_V7S_TCR_PD1BIT(5)
+#ifdef CONFIG_ZONE_DMA32
+#define ARM_V7S_TABLE_GFP_DMA GFP_DMA32
+#define ARM_V7S_TABLE_SLAB_CACHE SLAB_CACHE_DMA32
+#else
+#define ARM_V7S_TABLE_GFP_DMA GFP_DMA
+#define ARM_V7S_TABLE_SLAB_CACHE SLAB_CACHE_DMA
+#endif
+
typedef u32 arm_v7s_iopte;
static bool selftest_running;
@@ -198,13 +206,16 @@ static void *__arm_v7s_alloc_table(int lvl, gfp_t gfp,
void *table = NULL;
if (lvl == 1)
- table = (void *)__get_dma_pages(__GFP_ZERO, get_order(size));
+ table = (void *)__get_free_pages(
+ __GFP_ZERO | ARM_V7S_TABLE_GFP_DMA, get_order(size));
else if (lvl == 2)
- table = kmem_cache_zalloc(data->l2_tables, gfp | GFP_DMA);
+ table = kmem_cache_zalloc(data->l2_tables, gfp);
phys = virt_to_phys(table);
- if (phys != (arm_v7s_iopte)phys)
+ if (phys != (arm_v7s_iopte)phys) {
/* Doesn't fit in PTE */
+ dev_err(dev, "Page table does not fit in PTE: %pa", );
goto out_free;
+ }
if (table && !(cfg->quirks & IO_PGTABLE_QUIRK_NO_DMA)) {
dma = dma_map_single(dev, table, size, DMA_TO_DEVICE);
if (dma_mapping_error(dev, dma))
@@ -737,7 +748,7 @@ static struct io_pgtable *arm_v7s_alloc_pgtable(struct
io_pgtable_cfg *cfg,
data->l2_tables = kmem_cache_create("io-pgtable_armv7s_l2",
ARM_V7S_TABLE_SIZE(2),
ARM_V7S_TABLE_SIZE(2),
- SLAB_CACHE_DMA, NULL);
+ ARM_V7S_TABLE_SLAB_CACHE, NULL);
if (!data->l2_tables)
goto out_free_data;
--
2.20.0.rc2.403.gdbc3b29805-goog
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