Hi YF,
> The calling to kmem_cache_alloc for level 2 page table allocation may
> run in atomic context, and it fails sometimes when DMA32 zone runs out
> of memory.
>
> Since Mediatek IOMMU hardware support at most 35bit PA in page table,
s/Mediatek/MediaTek/
s/support/supports/
> so add a quirk to allow the PA of level 2 pgtable support bit35.
35bits PA, right?
>
>
...snip...
>
> phys = virt_to_phys(table);
> - if (phys != (arm_v7s_iopte)phys) {
> + if (phys != (arm_v7s_iopte)phys &&
> + !(cfg->quirks & IO_PGTABLE_QUIRK_ARM_MTK_TTBR_EXT)) {
I have one question while reading this.
If IO_PGTABLE_QUIRK_ARM_MTK_TTBR_EXT is set, it means that the phys can be up to 35 bits.
In aarch64, kmalloc() could return up to 52 bits PA (e.g., ARM64_PA_BITS_52=y)
How do we guarantee that phys is safe (<= 35 bits) in this case?
For example:
When IO_PGTABLE_QUIRK_ARM_MTK_TTBR_EXT is set, the platform guarantees its PAs are at most
35 bits?
Thanks,
Miles
> /* Doesn't fit in PTE */
> dev_err(dev, "Page table does not fit in PTE: %pa", &phys);
> goto out_free;
> @@ -457,9 +464,14 @@ static arm_v7s_iopte arm_v7s_install_table(arm_v7s_iopte *table,
> arm_v7s_iopte curr,
> struct io_pgtable_cfg *cfg)
> {
> + phys_addr_t phys = virt_to_phys(table);
> arm_v7s_iopte old, new;
>
> - new = virt_to_phys(table) | ARM_V7S_PTE_TYPE_TABLE;
> + new = phys | ARM_V7S_PTE_TYPE_TABLE;
> +
> + if (cfg->quirks & IO_PGTABLE_QUIRK_ARM_MTK_TTBR_EXT)
> + new = to_iopte_mtk(phys, new, cfg);
> +
> if (cfg->quirks & IO_PGTABLE_QUIRK_ARM_NS)
> new |= ARM_V7S_ATTR_NS_TABLE;
>
> @@ -778,6 +790,7 @@ static phys_addr_t arm_v7s_iova_to_phys(struct io_pgtable_ops *ops,
> static struct io_pgtable *arm_v7s_alloc_pgtable(struct io_pgtable_cfg *cfg,
> void *cookie)
> {
> + slab_flags_t slab_flag = ARM_V7S_TABLE_SLAB_FLAGS;
> struct arm_v7s_io_pgtable *data;
>
> if (cfg->ias > (arm_v7s_is_mtk_enabled(cfg) ? 34 : ARM_V7S_ADDR_BITS))
> @@ -788,7 +801,8 @@ static struct io_pgtable *arm_v7s_alloc_pgtable(struct io_pgtable_cfg *cfg,
>
> if (cfg->quirks & ~(IO_PGTABLE_QUIRK_ARM_NS |
> IO_PGTABLE_QUIRK_NO_PERMS |
> - IO_PGTABLE_QUIRK_ARM_MTK_EXT))
> + IO_PGTABLE_QUIRK_ARM_MTK_EXT |
> + IO_PGTABLE_QUIRK_ARM_MTK_TTBR_EXT))
> return NULL;
>
> /* If ARM_MTK_4GB is enabled, the NO_PERMS is also expected. */
> @@ -801,10 +815,12 @@ static struct io_pgtable *arm_v7s_alloc_pgtable(struct io_pgtable_cfg *cfg,
> return NULL;
>
> spin_lock_init(&data->split_lock);
> + if (cfg->quirks & IO_PGTABLE_QUIRK_ARM_MTK_TTBR_EXT)
> + slab_flag = 0;
> data->l2_tables = kmem_cache_create("io-pgtable_armv7s_l2",
> ARM_V7S_TABLE_SIZE(2, cfg),
> ARM_V7S_TABLE_SIZE(2, cfg),
> - ARM_V7S_TABLE_SLAB_FLAGS, NULL);
> + slab_flag, NULL);
> if (!data->l2_tables)
> goto out_free_data;
>
> diff --git a/include/linux/io-pgtable.h b/include/linux/io-pgtable.h
> index 86af6f0a00a2..7ed15ad4710c 100644
> --- a/include/linux/io-pgtable.h
> +++ b/include/linux/io-pgtable.h
> @@ -74,17 +74,22 @@ struct io_pgtable_cfg {
> * to support up to 35 bits PA where the bit32, bit33 and bit34 are
> * encoded in the bit9, bit4 and bit5 of the PTE respectively.
> *
> + * IO_PGTABLE_QUIRK_ARM_MTK_TTBR_EXT: (ARM v7s format) MediaTek IOMMUs
> + * extend the translation table support up to 35 bits PA, the
> + * encoding format is same with IO_PGTABLE_QUIRK_ARM_MTK_EXT.
> + *
> * IO_PGTABLE_QUIRK_ARM_TTBR1: (ARM LPAE format) Configure the table
> * for use in the upper half of a split address space.
> *
> * IO_PGTABLE_QUIRK_ARM_OUTER_WBWA: Override the outer-cacheability
> * attributes set in the TCR for a non-coherent page-table walker.
> */
> - #define IO_PGTABLE_QUIRK_ARM_NS BIT(0)
> - #define IO_PGTABLE_QUIRK_NO_PERMS BIT(1)
> - #define IO_PGTABLE_QUIRK_ARM_MTK_EXT BIT(3)
> - #define IO_PGTABLE_QUIRK_ARM_TTBR1 BIT(5)
> - #define IO_PGTABLE_QUIRK_ARM_OUTER_WBWA BIT(6)
> + #define IO_PGTABLE_QUIRK_ARM_NS BIT(0)
> + #define IO_PGTABLE_QUIRK_NO_PERMS BIT(1)
> + #define IO_PGTABLE_QUIRK_ARM_MTK_EXT BIT(3)
> + #define IO_PGTABLE_QUIRK_ARM_MTK_TTBR_EXT BIT(4)
> + #define IO_PGTABLE_QUIRK_ARM_TTBR1 BIT(5)
> + #define IO_PGTABLE_QUIRK_ARM_OUTER_WBWA BIT(6)
> unsigned long quirks;
> unsigned long pgsize_bitmap;
> unsigned int ias;
> --
> 2.18.0
>
>
