2018-04-09 21:10:22

by Laura Abbott

[permalink] [raw]
Subject: [PATCH] drm/amdkfd: Remove vla

There's an ongoing effort to remove VLAs[1] from the kernel to eventually
turn on -Wvla. The single VLA usage in the amdkfd driver is actually
constant across all current platforms. Switch to a constant size array
instead.

[1] https://lkml.org/lkml/2018/3/7/621

Signed-off-by: Laura Abbott <[email protected]>
---
drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c b/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c
index 035c351f47c5..c9863858f343 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c
@@ -139,10 +139,12 @@ static void interrupt_wq(struct work_struct *work)
{
struct kfd_dev *dev = container_of(work, struct kfd_dev,
interrupt_work);
+ uint32_t ih_ring_entry[4];

- uint32_t ih_ring_entry[DIV_ROUND_UP(
- dev->device_info->ih_ring_entry_size,
- sizeof(uint32_t))];
+ if (dev->device_info->ih_ring_entry_size > (4 * sizeof(uint32_t))) {
+ dev_err(kfd_chardev(), "Ring entry too small\n");
+ return;
+ }

while (dequeue_ih_ring_entry(dev, ih_ring_entry))
dev->device_info->event_interrupt_class->interrupt_wq(dev,
--
2.14.3



2018-04-10 06:43:22

by Christian König

[permalink] [raw]
Subject: Re: [PATCH] drm/amdkfd: Remove vla

Am 09.04.2018 um 23:06 schrieb Laura Abbott:
> There's an ongoing effort to remove VLAs[1] from the kernel to eventually
> turn on -Wvla. The single VLA usage in the amdkfd driver is actually
> constant across all current platforms.

Actually that isn't correct.

Could be that we haven't upstreamed KFD support for them, but Vega10
have a different interrupt ring entry size and so would cause the error
message here.

> Switch to a constant size array
> instead.

I would say to just make make the array bigger.

Regards,
Christian.

>
> [1] https://lkml.org/lkml/2018/3/7/621
>
> Signed-off-by: Laura Abbott <[email protected]>
> ---
> drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c b/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c
> index 035c351f47c5..c9863858f343 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c
> @@ -139,10 +139,12 @@ static void interrupt_wq(struct work_struct *work)
> {
> struct kfd_dev *dev = container_of(work, struct kfd_dev,
> interrupt_work);
> + uint32_t ih_ring_entry[4];
>
> - uint32_t ih_ring_entry[DIV_ROUND_UP(
> - dev->device_info->ih_ring_entry_size,
> - sizeof(uint32_t))];
> + if (dev->device_info->ih_ring_entry_size > (4 * sizeof(uint32_t))) {
> + dev_err(kfd_chardev(), "Ring entry too small\n");
> + return;
> + }
>
> while (dequeue_ih_ring_entry(dev, ih_ring_entry))
> dev->device_info->event_interrupt_class->interrupt_wq(dev,


2018-04-10 18:47:18

by Laura Abbott

[permalink] [raw]
Subject: Re: [PATCH] drm/amdkfd: Remove vla

On 04/09/2018 11:38 PM, Christian König wrote:
> Am 09.04.2018 um 23:06 schrieb Laura Abbott:
>> There's an ongoing effort to remove VLAs[1] from the kernel to eventually
>> turn on -Wvla. The single VLA usage in the amdkfd driver is actually
>> constant across all current platforms.
>
> Actually that isn't correct.
>
> Could be that we haven't upstreamed KFD support for them, but Vega10 have a different interrupt ring entry size and so would cause the error message here.
>
>> Switch to a constant size array
>> instead.
>
> I would say to just make make the array bigger.
>
> Regards,
> Christian.
>

What array size would accommodate future chips?

>>
>> [1] https://lkml.org/lkml/2018/3/7/621
>>
>> Signed-off-by: Laura Abbott <[email protected]>
>> ---
>>   drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c | 8 +++++---
>>   1 file changed, 5 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c b/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c
>> index 035c351f47c5..c9863858f343 100644
>> --- a/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c
>> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c
>> @@ -139,10 +139,12 @@ static void interrupt_wq(struct work_struct *work)
>>   {
>>       struct kfd_dev *dev = container_of(work, struct kfd_dev,
>>                           interrupt_work);
>> +    uint32_t ih_ring_entry[4];
>> -    uint32_t ih_ring_entry[DIV_ROUND_UP(
>> -                dev->device_info->ih_ring_entry_size,
>> -                sizeof(uint32_t))];
>> +    if (dev->device_info->ih_ring_entry_size > (4 * sizeof(uint32_t))) {
>> +        dev_err(kfd_chardev(), "Ring entry too small\n");
>> +        return;
>> +    }
>>       while (dequeue_ih_ring_entry(dev, ih_ring_entry))
>>           dev->device_info->event_interrupt_class->interrupt_wq(dev,
>


2018-04-10 18:49:21

by Felix Kuehling

[permalink] [raw]
Subject: Re: [PATCH] drm/amdkfd: Remove vla

Thanks Christian for catching that. I'm working on a patch series to
upstream Vega10 support, about 95% done. It will add this ASIC info for
Vega10:

static const struct kfd_device_info vega10_device_info = {
.asic_family = CHIP_VEGA10,
.max_pasid_bits = 16,
.max_no_of_hqd = 24,
.doorbell_size = 8,
.ih_ring_entry_size = 8 * sizeof(uint32_t), /* !!! IH ring entry size is bigger on Vega10 !!! */
.event_interrupt_class = &event_interrupt_class_v9,
.num_of_watch_points = 4,
.mqd_size_aligned = MQD_SIZE_ALIGNED,
.supports_cwsr = true,
.needs_iommu_device = false,
.needs_pci_atomics = false,
};

If you change it to uint32_t ih_ring_entry[8] and update the check, it
should be reasonably future proof.

Regards,
  Felix


On 2018-04-10 02:38 AM, Christian König wrote:
> Am 09.04.2018 um 23:06 schrieb Laura Abbott:
>> There's an ongoing effort to remove VLAs[1] from the kernel to
>> eventually
>> turn on -Wvla. The single VLA usage in the amdkfd driver is actually
>> constant across all current platforms.
>
> Actually that isn't correct.
>
> Could be that we haven't upstreamed KFD support for them, but Vega10
> have a different interrupt ring entry size and so would cause the
> error message here.
>
>> Switch to a constant size array
>> instead.
>
> I would say to just make make the array bigger.
>
> Regards,
> Christian.
>
>>
>> [1] https://lkml.org/lkml/2018/3/7/621
>>
>> Signed-off-by: Laura Abbott <[email protected]>
>> ---
>>   drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c | 8 +++++---
>>   1 file changed, 5 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c
>> b/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c
>> index 035c351f47c5..c9863858f343 100644
>> --- a/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c
>> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_interrupt.c
>> @@ -139,10 +139,12 @@ static void interrupt_wq(struct work_struct *work)
>>   {
>>       struct kfd_dev *dev = container_of(work, struct kfd_dev,
>>                           interrupt_work);
>> +    uint32_t ih_ring_entry[4];
>>   -    uint32_t ih_ring_entry[DIV_ROUND_UP(
>> -                dev->device_info->ih_ring_entry_size,
>> -                sizeof(uint32_t))];
>> +    if (dev->device_info->ih_ring_entry_size > (4 *
>> sizeof(uint32_t))) {
>> +        dev_err(kfd_chardev(), "Ring entry too small\n");
>> +        return;
>> +    }
>>         while (dequeue_ih_ring_entry(dev, ih_ring_entry))
>>           dev->device_info->event_interrupt_class->interrupt_wq(dev,
>
> _______________________________________________
> amd-gfx mailing list
> [email protected]
> https://lists.freedesktop.org/mailman/listinfo/amd-gfx