On 19/09/17 11:17 AM, Deucher, Alexander wrote:
-----Original Message-----
From: amd-gfx [mailto:amd-gfx-boun...@lists.freedesktop.org] On Behalf
Of Tom St Denis
Sent: Tuesday, September 19, 2017 8:13 AM
To: amd-gfx@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.stde...@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
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