+ Russell, Arnd
On Thursday 13 March 2014 10:47 PM, Anna, Suman wrote:
> Hi Laurent,
>
> On 03/07/2014 06:46 PM, Laurent Pinchart wrote:
>> The page table entries must be cleaned from the cache before being
>> accessed by the IOMMU. Instead of implementing cache management manually
>> (and ignoring L2 cache), use clean_dcache_area() to make sure the
>> entries are visible to the device.
>
> Thanks for fixing this, this has been long pending. There have been some
> previous attempts at this as well by Ramesh Gupta, with the last thread
> (a long time now) being
> http://marc.info/?t=134752035400001&r=1&w=2
>
> Santosh,
> Can you please take a look at this patch and provide your comments?
>
> regards
> Suman
>
>>
>> Signed-off-by: Laurent Pinchart <[email protected]>
>> ---
>> drivers/iommu/omap-iommu.c | 41 ++++++++++-------------------------------
>> 1 file changed, 10 insertions(+), 31 deletions(-)
>>
>> diff --git a/drivers/iommu/omap-iommu.c b/drivers/iommu/omap-iommu.c
>> index a893eca..bb605c9 100644
>> --- a/drivers/iommu/omap-iommu.c
>> +++ b/drivers/iommu/omap-iommu.c
>> @@ -500,24 +500,9 @@ EXPORT_SYMBOL_GPL(omap_foreach_iommu_device);
>> /*
>> * H/W pagetable operations
>> */
>> -static void flush_iopgd_range(u32 *first, u32 *last)
>> +static void flush_pgtable(void *addr, size_t size)
>> {
>> - /* FIXME: L2 cache should be taken care of if it exists */
>> - do {
>> - asm("mcr p15, 0, %0, c7, c10, 1 @ flush_pgd"
>> - : : "r" (first));
>> - first += L1_CACHE_BYTES / sizeof(*first);
>> - } while (first <= last);
>> -}
>> -
>> -static void flush_iopte_range(u32 *first, u32 *last)
>> -{
>> - /* FIXME: L2 cache should be taken care of if it exists */
>> - do {
>> - asm("mcr p15, 0, %0, c7, c10, 1 @ flush_pte"
>> - : : "r" (first));
>> - first += L1_CACHE_BYTES / sizeof(*first);
>> - } while (first <= last);
>> + clean_dcache_area(addr, size);
I remember NAKing this approach in past and my stand remains same.
The cache APIs which you are trying to use here are not suppose
to be used outside.
I think the right way to fix this is to make use of streaming APIs.
If needed, IOMMU can have its own dma_ops for special case
handling if any.
Russell, Arnd might have more ideas.
>> }
>>
>> static void iopte_free(u32 *iopte)
>> @@ -546,7 +531,7 @@ static u32 *iopte_alloc(struct omap_iommu *obj, u32
>> *iopgd, u32 da)
>> return ERR_PTR(-ENOMEM);
>>
>> *iopgd = virt_to_phys(iopte) | IOPGD_TABLE;
>> - flush_iopgd_range(iopgd, iopgd);
>> + flush_pgtable(iopgd, sizeof(*iopgd));
>>
>> dev_vdbg(obj->dev, "%s: a new pte:%p\n", __func__, iopte);
>> } else {
>> @@ -575,7 +560,7 @@ static int iopgd_alloc_section(struct omap_iommu *obj,
>> u32 da, u32 pa, u32 prot)
>> }
>>
>> *iopgd = (pa & IOSECTION_MASK) | prot | IOPGD_SECTION;
>> - flush_iopgd_range(iopgd, iopgd);
>> + flush_pgtable(iopgd, sizeof(*iopgd));
>> return 0;
>> }
>>
>> @@ -592,7 +577,7 @@ static int iopgd_alloc_super(struct omap_iommu *obj, u32
>> da, u32 pa, u32 prot)
>>
>> for (i = 0; i < 16; i++)
>> *(iopgd + i) = (pa & IOSUPER_MASK) | prot | IOPGD_SUPER;
>> - flush_iopgd_range(iopgd, iopgd + 15);
>> + flush_pgtable(iopgd, sizeof(*iopgd) * 16);
>> return 0;
>> }
>>
>> @@ -605,7 +590,7 @@ static int iopte_alloc_page(struct omap_iommu *obj, u32
>> da, u32 pa, u32 prot)
>> return PTR_ERR(iopte);
>>
>> *iopte = (pa & IOPAGE_MASK) | prot | IOPTE_SMALL;
>> - flush_iopte_range(iopte, iopte);
>> + flush_pgtable(iopte, sizeof(*iopte));
>>
>> dev_vdbg(obj->dev, "%s: da:%08x pa:%08x pte:%p *pte:%08x\n",
>> __func__, da, pa, iopte, *iopte);
>> @@ -619,18 +604,12 @@ static int iopte_alloc_large(struct omap_iommu *obj,
>> u32 da, u32 pa, u32 prot)
>> u32 *iopte = iopte_alloc(obj, iopgd, da);
>> int i;
>>
>> - if ((da | pa) & ~IOLARGE_MASK) {
>> - dev_err(obj->dev, "%s: %08x:%08x should aligned on %08lx\n",
>> - __func__, da, pa, IOLARGE_SIZE);
>> - return -EINVAL;
>> - }
>> -
>> if (IS_ERR(iopte))
>> return PTR_ERR(iopte);
>>
>> for (i = 0; i < 16; i++)
>> *(iopte + i) = (pa & IOLARGE_MASK) | prot | IOPTE_LARGE;
>> - flush_iopte_range(iopte, iopte + 15);
>> + flush_pgtable(iopte, sizeof(*iopte) * 16);
>> return 0;
>> }
>>
>> @@ -733,7 +712,7 @@ static size_t iopgtable_clear_entry_core(struct
>> omap_iommu *obj, u32 da)
>> }
>> bytes *= nent;
>> memset(iopte, 0, nent * sizeof(*iopte));
>> - flush_iopte_range(iopte, iopte + (nent - 1) * sizeof(*iopte));
>> + flush_pgtable(iopte, sizeof(*iopte) * nent);
>>
>> /*
>> * do table walk to check if this table is necessary or not
>> @@ -755,7 +734,7 @@ static size_t iopgtable_clear_entry_core(struct
>> omap_iommu *obj, u32 da)
>> bytes *= nent;
>> }
>> memset(iopgd, 0, nent * sizeof(*iopgd));
>> - flush_iopgd_range(iopgd, iopgd + (nent - 1) * sizeof(*iopgd));
>> + flush_pgtable(iopgd, sizeof(*iopgd) * nent);
>> out:
>> return bytes;
>> }
>> @@ -799,7 +778,7 @@ static void iopgtable_clear_entry_all(struct omap_iommu
>> *obj)
>> iopte_free(iopte_offset(iopgd, 0));
>>
>> *iopgd = 0;
>> - flush_iopgd_range(iopgd, iopgd);
>> + flush_pgtable(iopgd, sizeof(*iopgd));
>> }
>>
>> flush_iotlb_all(obj);
>>
>
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