On 11/7/22 19:50, Robin Murphy wrote:
> On 2022-11-04 20:48, Dmitry Osipenko wrote:
>> On 11/4/22 23:37, Robin Murphy wrote:
>>> On 2022-11-04 20:11, Dmitry Osipenko wrote:
>>>> On 8/23/22 01:01, Robin Murphy wrote:
>>>>> Convert to io-pgtable's bulk {map,unmap}_pages() APIs, to help the old
>>>>> single-page interfaces eventually go away. Unmapping heap BOs still
>>>>> wants to be done a page at a time, but everything else can get the
>>>>> full
>>>>> benefit of the more efficient interface.
>>>>>
>>>>> Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx>
>>>>> ---
>>>>> drivers/gpu/drm/panfrost/panfrost_mmu.c | 40
>>>>> +++++++++++++++----------
>>>>> 1 file changed, 25 insertions(+), 15 deletions(-)
>>>>>
>>>>> diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c
>>>>> b/drivers/gpu/drm/panfrost/panfrost_mmu.c
>>>>> index b285a8001b1d..e246d914e7f6 100644
>>>>> --- a/drivers/gpu/drm/panfrost/panfrost_mmu.c
>>>>> +++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c
>>>>> @@ -248,11 +248,15 @@ void panfrost_mmu_reset(struct panfrost_device
>>>>> *pfdev)
>>>>> mmu_write(pfdev, MMU_INT_MASK, ~0);
>>>>> }
>>>>> -static size_t get_pgsize(u64 addr, size_t size)
>>>>> +static size_t get_pgsize(u64 addr, size_t size, size_t *count)
>>>>> {
>>>>> - if (addr & (SZ_2M - 1) || size < SZ_2M)
>>>>> - return SZ_4K;
>>>>> + size_t blk_offset = -addr % SZ_2M;
>>>>> + if (blk_offset || size < SZ_2M) {
>>>>> + *count = min_not_zero(blk_offset, size) / SZ_4K;
>>>>> + return SZ_4K;
>>>>> + }
>>>>> + *count = size / SZ_2M;
>>>>> return SZ_2M;
>>>>> }
>>>>> @@ -287,12 +291,16 @@ static int mmu_map_sg(struct panfrost_device
>>>>> *pfdev, struct panfrost_mmu *mmu,
>>>>> dev_dbg(pfdev->dev, "map: as=%d, iova=%llx, paddr=%lx,
>>>>> len=%zx", mmu->as, iova, paddr, len);
>>>>> while (len) {
>>>>> - size_t pgsize = get_pgsize(iova | paddr, len);
>>>>> + size_t pgcount, mapped = 0;
>>>>> + size_t pgsize = get_pgsize(iova | paddr, len, &pgcount);
>>>>> - ops->map(ops, iova, paddr, pgsize, prot, GFP_KERNEL);
>>>>> - iova += pgsize;
>>>>> - paddr += pgsize;
>>>>> - len -= pgsize;
>>>>> + ops->map_pages(ops, iova, paddr, pgsize, pgcount, prot,
>>>>> + GFP_KERNEL, &mapped);
>>>>> + /* Don't get stuck if things have gone wrong */
>>>>> + mapped = max(mapped, pgsize);
>>>>> + iova += mapped;
>>>>> + paddr += mapped;
>>>>> + len -= mapped;
>>>>> }
>>>>> }
>>>>> @@ -344,15 +352,17 @@ void panfrost_mmu_unmap(struct
>>>>> panfrost_gem_mapping *mapping)
>>>>> mapping->mmu->as, iova, len);
>>>>> while (unmapped_len < len) {
>>>>> - size_t unmapped_page;
>>>>> - size_t pgsize = get_pgsize(iova, len - unmapped_len);
>>>>> + size_t unmapped_page, pgcount;
>>>>> + size_t pgsize = get_pgsize(iova, len - unmapped_len,
>>>>> &pgcount);
>>>>> - if (ops->iova_to_phys(ops, iova)) {
>>>>> - unmapped_page = ops->unmap(ops, iova, pgsize, NULL);
>>>>> - WARN_ON(unmapped_page != pgsize);
>>>>> + if (bo->is_heap)
>>>>> + pgcount = 1;
>>>>> + if (!bo->is_heap || ops->iova_to_phys(ops, iova)) {
>>>>> + unmapped_page = ops->unmap_pages(ops, iova, pgsize,
>>>>> pgcount, NULL);
>>>>> + WARN_ON(unmapped_page != pgsize * pgcount);
>>>>
>>>> This patch causes this WARN_ON to trigger. It doesn't happen all the
>>>> time, I see that the whole unmapped area is mapped. Initially, I
>>>> thought
>>>> that this happens because it tries to unmap a partially mapped range,
>>>> but I checked that ops->iova_to_phys() returns address for all 4k
>>>> chunks.
>>>>
>>>> For example the pgsize * pgcount = 0x8000000, while returned
>>>> unmapped_page = 0x6000000.
>>>>
>>>> I don't see this problem with this patch reverted. This is using
>>>> today's
>>>> linux-next. Any ideas?
>>>
>>> What's the base IOVA in such a case? I'm wondering if the truncated size
>>> lines up to any interesting boundary. Presumably you're not seeing any
>>> additional warnings from io-pgtable itself?
>>
>> No warnings from io-pgtable. It succeeds for 0x32000000 and fails for
>> 0x3a000000 using same size 0x8000000. It actually fails only for the
>> 0x3a000000 as far as I see from my logs. Perhaps it indeed has to do
>> something with the boundary.
>
> Bleh, indeed even though we don't use 1GB block mappings, we still need
> to split at 1GB boundaries to match what the IOMMU API will do, and thus
> what io-pgtable expects. I guess I hadn't really considered that we
> might ever have that much graphics memory in play at once...
>
> The fix probably looks like this:
>
> diff --git a/drivers/gpu/drm/panfrost/panfrost_mmu.c
> b/drivers/gpu/drm/panfrost/panfrost_mmu.c
> index e246d914e7f6..6abc7d3726dd 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_mmu.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_mmu.c
> @@ -256,7 +256,9 @@ static size_t get_pgsize(u64 addr, size_t size,
> size_t *count)
> *count = min_not_zero(blk_offset, size) / SZ_4K;
> return SZ_4K;
> }
> - *count = size / SZ_2M;
> +
> + blk_offset = -addr % SZ_1G;
> + *count = min_not_zero(blk_offset, size) / SZ_2M;
> return SZ_2M;
> }
The warning is gone with this change applied, thank you!
Tested-by: Dmitry Osipenko <dmitry.osipenko@xxxxxxxxxxxxx>
Will be great if you could add explanatory comment to the code once
you'll send a proper patch.
--
Best regards,
Dmitry
