[PATCH 2/4] drm/amd/amdgpu: add support for iova_to_phys to replace TTM trace

[Christian König]

Am 18.09.2017 um 14:35 schrieb Tom St Denis:
> Signed-off-by: Tom St Denis <tom.stdenis at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 32 ++++++++++++++++++++++++++++++++
>   1 file changed, 32 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> index 7848ffa99eb4..b4c298925e2a 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> @@ -43,6 +43,7 @@
>   #include <linux/swap.h>
>   #include <linux/pagemap.h>
>   #include <linux/debugfs.h>
> +#include <linux/iommu.h>
>   #include "amdgpu.h"
>   #include "amdgpu_trace.h"
>   #include "bif/bif_4_1_d.h"
> @@ -1810,6 +1811,36 @@ static const struct file_operations amdgpu_ttm_gtt_fops = {
>   #endif
>   
>   
> +static ssize_t amdgpu_iova_to_phys_read(struct file *f, char __user *buf,
> +				   size_t size, loff_t *pos)
> +{
> +	struct amdgpu_device *adev = file_inode(f)->i_private;
> +	int r;
> +	uint64_t phys;
> +
> +	// always return 8 bytes
> +	if (size != 8)
> +		return -EINVAL;
> +
> +	// only accept page addresses
> +	if (*pos & 0xFFF)
> +		return -EINVAL;
> +
> +
> +	phys = iommu_iova_to_phys(iommu_get_domain_for_dev(adev->dev), *pos);

Well how about adding directly read/write support for the page behind 
the address?

This way we won't need to fiddle with /dev/mem any more either.

Christian.

> +
> +	r = copy_to_user(buf, &phys, 8);
> +	if (r)
> +		return -EFAULT;
> +
> +	return 8;
> +}
> +
> +static const struct file_operations amdgpu_ttm_iova_fops = {
> +	.owner = THIS_MODULE,
> +	.read = amdgpu_iova_to_phys_read,
> +	.llseek = default_llseek
> +};
>   
>   static const struct {
>   	char *name;
> @@ -1819,6 +1850,7 @@ static const struct {
>   #ifdef CONFIG_DRM_AMDGPU_GART_DEBUGFS
>   	{ "amdgpu_gtt", &amdgpu_ttm_gtt_fops },
>   #endif
> +	{ "amdgpu_iova", &amdgpu_ttm_iova_fops },
>   };
>   
>   #endif