[PATCH] drm/amd/amdgpu: add support for iova_to_phys to replace TTM trace (v5)
Tom St Denis
tom.stdenis at amd.com
Tue Sep 19 15:28:07 UTC 2017
Booting with IOMMU disabled in the bios breaks this.
I'll submit a fix in a minute. Should be easy.
Tom
On 19/09/17 11:25 AM, Tom St Denis wrote:
> On 19/09/17 11:17 AM, Deucher, Alexander wrote:
>>> -----Original Message-----
>>> From: amd-gfx [mailto:amd-gfx-bounces at lists.freedesktop.org] On Behalf
>>> Of Tom St Denis
>>> Sent: Tuesday, September 19, 2017 8:13 AM
>>> To: amd-gfx at lists.freedesktop.org
>>> Cc: StDenis, Tom
>>> Subject: [PATCH] drm/amd/amdgpu: add support for iova_to_phys to
>>> replace TTM trace (v5)
>>>
>>> Signed-off-by: Tom St Denis <tom.stdenis at amd.com>
>>>
>>> (v2): Add domain to iova debugfs
>>> (v3): Add true read/write methods to access system memory of pages
>>> mapped to the device
>>> (v4): Move get_domain call out of loop and return on error
>>> (v5): Just use kmap/kunmap
>>> ---
>>> drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 99
>>> +++++++++++++++++++++++++++++++++
>>> 1 file changed, 99 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>>> index 50d20903de4f..c7f8e081a772 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm
>>> +++ 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>
>>
>> Just to double check, do you need any compile guards for the IOMMU
>> disabled case?
>
> I honestly don't know. Is there an easy way to setup a cross build that
> won't automagically enable the iommu in the configuration?
>
> (also, if the iommu team co-operated from the get go...).
>
> Looking at the cavium thunder ethernet source (I grepped for
> iova_to_phys) it seems the return of dev_to_domain might be NULL if
> IOMMU is disabled in which case these read/writes will return -EFAULT...
>
> ideally the iommu_iova_to_phys() would be an identity function if the
> domain is NULL. Which it doesn't. It'll OOPS if domain==NULL.
>
> So the fix might be to skip the iova_to_phys call if domain==NULL and
> act on the address as a physical address.
>
> On my carrizo with IOMMU enabled I can read the gfx ring buffer directly
> with --vm-read for both the Carrizo and Polaris10 (the Carrizo doesn't
> do mapping, the Polaris10 does). I can try a boot with iommu disabled
> and see what happens.
>
> Tom
>
>
>>
>> Alex
>>
>>> #include "amdgpu.h"
>>> #include "amdgpu_trace.h"
>>> #include "bif/bif_4_1_d.h"
>>> @@ -1809,7 +1810,104 @@ 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;
>>> + ssize_t result, n;
>>> + int r;
>>> + uint64_t phys;
>>> + void *ptr;
>>> + struct iommu_domain *dom;
>>> +
>>> + dom = iommu_get_domain_for_dev(adev->dev);
>>> + if (!dom)
>>> + return -EFAULT;
>>> +
>>> + result = 0;
>>> + while (size) {
>>> + // get physical address and map
>>> + phys = iommu_iova_to_phys(dom, *pos);
>>> +
>>> + // copy upto one page
>>> + if (size > PAGE_SIZE)
>>> + n = PAGE_SIZE;
>>> + else
>>> + n = size;
>>> +
>>> + // to end of the page
>>> + if (((*pos & (PAGE_SIZE - 1)) + n) >= PAGE_SIZE)
>>> + n = PAGE_SIZE - (*pos & (PAGE_SIZE - 1));
>>> +
>>> + ptr = kmap(pfn_to_page(PFN_DOWN(phys)));
>>> + if (!ptr)
>>> + return -EFAULT;
>>> +
>>> + r = copy_to_user(buf, ptr, n);
>>> + kunmap(pfn_to_page(PFN_DOWN(phys)));
>>> + if (r)
>>> + return -EFAULT;
>>> +
>>> + *pos += n;
>>> + size -= n;
>>> + result += n;
>>> + }
>>> +
>>> + return result;
>>> +}
>>> +
>>> +static ssize_t amdgpu_iova_to_phys_write(struct file *f, const char
>>> __user
>>> *buf,
>>> + size_t size, loff_t *pos)
>>> +{
>>> + struct amdgpu_device *adev = file_inode(f)->i_private;
>>> + ssize_t result, n;
>>> + int r;
>>> + uint64_t phys;
>>> + void *ptr;
>>> + struct iommu_domain *dom;
>>> +
>>> + dom = iommu_get_domain_for_dev(adev->dev);
>>> + if (!dom)
>>> + return -EFAULT;
>>> +
>>> + result = 0;
>>> + while (size) {
>>> + // get physical address and map
>>> + phys = iommu_iova_to_phys(dom, *pos);
>>>
>>> + // copy upto one page
>>> + if (size > PAGE_SIZE)
>>> + n = PAGE_SIZE;
>>> + else
>>> + n = size;
>>> +
>>> + // to end of the page
>>> + if (((*pos & (PAGE_SIZE - 1)) + n) >= PAGE_SIZE)
>>> + n = PAGE_SIZE - (*pos & (PAGE_SIZE - 1));
>>> +
>>> + ptr = kmap(pfn_to_page(PFN_DOWN(phys)));
>>> + if (!ptr)
>>> + return -EFAULT;
>>> +
>>> + r = copy_from_user(ptr, buf, n);
>>> + kunmap(pfn_to_page(PFN_DOWN(phys)));
>>> + if (r)
>>> + return -EFAULT;
>>> +
>>> + *pos += n;
>>> + size -= n;
>>> + result += n;
>>> + }
>>> +
>>> + return result;
>>> +}
>>> +
>>> +static const struct file_operations amdgpu_ttm_iova_fops = {
>>> + .owner = THIS_MODULE,
>>> + .read = amdgpu_iova_to_phys_read,
>>> + .write = amdgpu_iova_to_phys_write,
>>> + .llseek = default_llseek
>>> +};
>>>
>>> static const struct {
>>> char *name;
>>> @@ -1820,6 +1918,7 @@ static const struct {
>>> #ifdef CONFIG_DRM_AMDGPU_GART_DEBUGFS
>>> { "amdgpu_gtt", &amdgpu_ttm_gtt_fops, TTM_PL_TT },
>>> #endif
>>> + { "amdgpu_iova", &amdgpu_ttm_iova_fops, TTM_PL_SYSTEM },
>>> };
>>>
>>> #endif
>>> --
>>> 2.12.0
>>>
>>> _______________________________________________
>>> amd-gfx mailing list
>>> amd-gfx at lists.freedesktop.org
>>> https://lists.freedesktop.org/mailman/listinfo/amd-gfx
>
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