diff mbox

drm/i915: Avoid writing relocs with addresses in non-canonical form

Message ID 1449228824-27152-1-git-send-email-michal.winiarski@intel.com (mailing list archive)
State New, archived
Headers show

Commit Message

Michał Winiarski Dec. 4, 2015, 11:33 a.m. UTC
According to bspec, some parts of HW expect the addresses to be in
a canonical form, where bits [63:48] == [47]. Let's convert addresses to
canonical form prior to relocating and return converted offsets to
userspace.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michel Thierry <michel.thierry@intel.com>
Signed-off-by: Micha? Winiarski <michal.winiarski@intel.com>
---
 drivers/gpu/drm/i915/i915_gem_execbuffer.c | 9 ++++++---
 drivers/gpu/drm/i915/i915_gem_gtt.h        | 5 +++++
 2 files changed, 11 insertions(+), 3 deletions(-)

Comments

Ville Syrjälä Dec. 4, 2015, 11:56 a.m. UTC | #1
On Fri, Dec 04, 2015 at 12:33:44PM +0100, Micha? Winiarski wrote:
> According to bspec, some parts of HW expect the addresses to be in
> a canonical form, where bits [63:48] == [47]. Let's convert addresses to
> canonical form prior to relocating and return converted offsets to
> userspace.
> 
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Michel Thierry <michel.thierry@intel.com>
> Signed-off-by: Micha? Winiarski <michal.winiarski@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_gem_execbuffer.c | 9 ++++++---
>  drivers/gpu/drm/i915/i915_gem_gtt.h        | 5 +++++
>  2 files changed, 11 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> index a4c243c..9f27be9 100644
> --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> @@ -395,7 +395,7 @@ i915_gem_execbuffer_relocate_entry(struct drm_i915_gem_object *obj,
>  	target_i915_obj = target_vma->obj;
>  	target_obj = &target_vma->obj->base;
>  
> -	target_offset = target_vma->node.start;
> +	target_offset = gen8_canonical_addr(target_vma->node.start);
>  
>  	/* Sandybridge PPGTT errata: We need a global gtt mapping for MI and
>  	 * pipe_control writes because the gpu doesn't properly redirect them
> @@ -583,6 +583,7 @@ i915_gem_execbuffer_reserve_vma(struct i915_vma *vma,
>  	struct drm_i915_gem_object *obj = vma->obj;
>  	struct drm_i915_gem_exec_object2 *entry = vma->exec_entry;
>  	uint64_t flags;
> +	uint64_t offset;
>  	int ret;
>  
>  	flags = PIN_USER;
> @@ -623,8 +624,10 @@ i915_gem_execbuffer_reserve_vma(struct i915_vma *vma,
>  			entry->flags |= __EXEC_OBJECT_HAS_FENCE;
>  	}
>  
> -	if (entry->offset != vma->node.start) {
> -		entry->offset = vma->node.start;
> +	offset = gen8_canonical_addr(vma->node.start);
> +
> +	if (entry->offset != offset) {
> +		entry->offset = offset;
>  		*need_reloc = true;
>  	}
>  
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.h b/drivers/gpu/drm/i915/i915_gem_gtt.h
> index 877c32c..65e8f88 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.h
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.h
> @@ -507,6 +507,11 @@ static inline size_t gen8_pte_count(uint64_t address, uint64_t length)
>  	return i915_pte_count(address, length, GEN8_PDE_SHIFT);
>  }
>  
> +static inline uint64_t gen8_canonical_addr(uint64_t address)
> +{
> +	return ((int64_t)address << 16) >> 16;
> +}

This could really use a comment explaining what it's doing and why.
Just lifting the first sentence of your commit message into a comment
would seem to be enough.

> +
>  static inline dma_addr_t
>  i915_page_dir_dma_addr(const struct i915_hw_ppgtt *ppgtt, const unsigned n)
>  {
> -- 
> 2.5.0
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
Chris Wilson Dec. 4, 2015, 12:05 p.m. UTC | #2
On Fri, Dec 04, 2015 at 12:33:44PM +0100, Micha? Winiarski wrote:
> According to bspec, some parts of HW expect the addresses to be in
> a canonical form, where bits [63:48] == [47]. Let's convert addresses to
> canonical form prior to relocating and return converted offsets to
> userspace.
> 
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Michel Thierry <michel.thierry@intel.com>
> Signed-off-by: Micha? Winiarski <michal.winiarski@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_gem_execbuffer.c | 9 ++++++---
>  drivers/gpu/drm/i915/i915_gem_gtt.h        | 5 +++++
>  2 files changed, 11 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> index a4c243c..9f27be9 100644
> --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> @@ -395,7 +395,7 @@ i915_gem_execbuffer_relocate_entry(struct drm_i915_gem_object *obj,
>  	target_i915_obj = target_vma->obj;
>  	target_obj = &target_vma->obj->base;
>  
> -	target_offset = target_vma->node.start;
> +	target_offset = gen8_canonical_addr(target_vma->node.start);

Ok, this keeps userspace in sync as well as writing the cannonical
addreses to hardware.

>  	/* Sandybridge PPGTT errata: We need a global gtt mapping for MI and
>  	 * pipe_control writes because the gpu doesn't properly redirect them
> @@ -583,6 +583,7 @@ i915_gem_execbuffer_reserve_vma(struct i915_vma *vma,
>  	struct drm_i915_gem_object *obj = vma->obj;
>  	struct drm_i915_gem_exec_object2 *entry = vma->exec_entry;
>  	uint64_t flags;
> +	uint64_t offset;
>  	int ret;
>  
>  	flags = PIN_USER;
> @@ -623,8 +624,10 @@ i915_gem_execbuffer_reserve_vma(struct i915_vma *vma,
>  			entry->flags |= __EXEC_OBJECT_HAS_FENCE;
>  	}
>  
> -	if (entry->offset != vma->node.start) {
> -		entry->offset = vma->node.start;
> +	offset = gen8_canonical_addr(vma->node.start);
> +

Kill the extra line.

> +	if (entry->offset != offset) {
> +		entry->offset = offset;
>  		*need_reloc = true;

And this copies back the cannonical address to userspace. Ok, the
userspace side looks correct (the presumed_offset and execobject.offsets
will be updated to store the cannonical address).

>  	}
>  
> diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.h b/drivers/gpu/drm/i915/i915_gem_gtt.h
> index 877c32c..65e8f88 100644
> --- a/drivers/gpu/drm/i915/i915_gem_gtt.h
> +++ b/drivers/gpu/drm/i915/i915_gem_gtt.h
> @@ -507,6 +507,11 @@ static inline size_t gen8_pte_count(uint64_t address, uint64_t length)
>  	return i915_pte_count(address, length, GEN8_PDE_SHIFT);
>  }
>  
> +static inline uint64_t gen8_canonical_addr(uint64_t address)
> +{

You need the bspec reference here as well.

Looks good to me, with just a quick explanation here as to what we are
doing and why.
-Chris
diff mbox

Patch

diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index a4c243c..9f27be9 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -395,7 +395,7 @@  i915_gem_execbuffer_relocate_entry(struct drm_i915_gem_object *obj,
 	target_i915_obj = target_vma->obj;
 	target_obj = &target_vma->obj->base;
 
-	target_offset = target_vma->node.start;
+	target_offset = gen8_canonical_addr(target_vma->node.start);
 
 	/* Sandybridge PPGTT errata: We need a global gtt mapping for MI and
 	 * pipe_control writes because the gpu doesn't properly redirect them
@@ -583,6 +583,7 @@  i915_gem_execbuffer_reserve_vma(struct i915_vma *vma,
 	struct drm_i915_gem_object *obj = vma->obj;
 	struct drm_i915_gem_exec_object2 *entry = vma->exec_entry;
 	uint64_t flags;
+	uint64_t offset;
 	int ret;
 
 	flags = PIN_USER;
@@ -623,8 +624,10 @@  i915_gem_execbuffer_reserve_vma(struct i915_vma *vma,
 			entry->flags |= __EXEC_OBJECT_HAS_FENCE;
 	}
 
-	if (entry->offset != vma->node.start) {
-		entry->offset = vma->node.start;
+	offset = gen8_canonical_addr(vma->node.start);
+
+	if (entry->offset != offset) {
+		entry->offset = offset;
 		*need_reloc = true;
 	}
 
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.h b/drivers/gpu/drm/i915/i915_gem_gtt.h
index 877c32c..65e8f88 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.h
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.h
@@ -507,6 +507,11 @@  static inline size_t gen8_pte_count(uint64_t address, uint64_t length)
 	return i915_pte_count(address, length, GEN8_PDE_SHIFT);
 }
 
+static inline uint64_t gen8_canonical_addr(uint64_t address)
+{
+	return ((int64_t)address << 16) >> 16;
+}
+
 static inline dma_addr_t
 i915_page_dir_dma_addr(const struct i915_hw_ppgtt *ppgtt, const unsigned n)
 {