Provide a mechanism for userspace to wait for kernel fences, and teach the
CS ioctl to return enough information to let userspace use this mechanism.
This mechanism isn't safe to include as-is, as there is no way for the CS
ioctl to indicate that it hasn't given you the information needed to let you
wait for a kernel fence. I'm thus sending it out as a starting point in case
someone else wants to continue digging into this.
Signed-off-by: Simon Farnsworth <simon.farnsworth at onelan.co.uk>
---
Note the FIXME - how does the CS ioctl indicate a fence failure?
I'm also a little concerned that my general userspace API isn't flexible
enough to match what we actually want - in particular, it would be nice for
GL_ARB_sync to be able to plonk fences down scattered throughout the IB, and
wait for that fence, not the whole CS. I couldn't easily determine whether
it was safe to add a kernel fence to a userspace IB during parsing, though,
so didn't attempt to do that.
Finally, this mechanism (as compared to the wait mechanism I proposed in
[PATCH] drm/radeon: Add support for userspace fence waits), doesn't do
anything to protect us against malicious userspace causing interrupt storms
- userspace can still fill an IB with EVENT_WRITE_EOP packets requesting an
interrupt, and this mechanism allows userspace to ensure that the interrupt
is enabled.
Someone needs to decide if that's a risk worth worrying about - if so, the
CS checkers need to reject attempts by userspace to request interrupts on
completion.
drivers/gpu/drm/radeon/radeon.h | 3 +++
drivers/gpu/drm/radeon/radeon_cs.c | 25 +++++++++++++++++++++++++
drivers/gpu/drm/radeon/radeon_fence.c | 16 ++++++++++++++++
drivers/gpu/drm/radeon/radeon_kms.c | 1 +
include/drm/radeon_drm.h | 15 +++++++++++++++
5 files changed, 60 insertions(+), 0 deletions(-)
diff --git a/drivers/gpu/drm/radeon/radeon.h b/drivers/gpu/drm/radeon/radeon.h
index b4cfb11..f26744a 100644
--- a/drivers/gpu/drm/radeon/radeon.h
+++ b/drivers/gpu/drm/radeon/radeon.h
@@ -800,6 +800,7 @@ struct radeon_cs_parser {
int chunk_ib_idx;
int chunk_relocs_idx;
int chunk_flags_idx;
+ int chunk_fence_idx;
struct radeon_ib *ib;
void *track;
unsigned family;
@@ -1348,6 +1349,8 @@ int radeon_gem_set_tiling_ioctl(struct drm_device *dev,
void *data,
struct drm_file *filp);
int radeon_gem_get_tiling_ioctl(struct drm_device *dev, void *data,
struct drm_file *filp);
+int radeon_fence_wait_value_ioctl(struct drm_device *dev, void *data,
+ struct drm_file *filp);
/* VRAM scratch page for HDP bug, default vram page */
struct r600_vram_scratch {
diff --git a/drivers/gpu/drm/radeon/radeon_cs.c
b/drivers/gpu/drm/radeon/radeon_cs.c
index 435a3d9..e0e8165 100644
--- a/drivers/gpu/drm/radeon/radeon_cs.c
+++ b/drivers/gpu/drm/radeon/radeon_cs.c
@@ -163,6 +163,7 @@ int radeon_cs_parser_init(struct radeon_cs_parser *p, void
*data)
p->chunk_ib_idx = -1;
p->chunk_relocs_idx = -1;
p->chunk_flags_idx = -1;
+ p->chunk_fence_idx = -1;
p->chunks_array = kcalloc(cs->num_chunks, sizeof(uint64_t), GFP_KERNEL);
if (p->chunks_array == NULL) {
return -ENOMEM;
@@ -207,6 +208,12 @@ int radeon_cs_parser_init(struct radeon_cs_parser *p, void
*data)
if (p->chunks[i].length_dw == 0)
return -EINVAL;
}
+ if (p->chunks[i].chunk_id == RADEON_CHUNK_ID_FENCE) {
+ p->chunk_fence_idx = i;
+ /* A fence chunk must be able to store the
end-of-stream fence */
+ if (p->chunks[i].length_dw != (sizeof(struct
drm_radeon_fence_wait) / 4))
+ return -EINVAL;
+ }
p->chunks[i].length_dw = user_chunk.length_dw;
p->chunks[i].user_ptr = (void __user *)(unsigned
long)user_chunk.chunk_data;
@@ -279,6 +286,24 @@ int radeon_cs_parser_init(struct radeon_cs_parser *p, void
*data)
return 0;
}
+static void radeon_cs_parser_output_fence(struct radeon_cs_parser *parser)
+{
+ struct drm_radeon_fence_wait output;
+ void __user* chunk;
+
+ memset(&output, 0, sizeof(struct drm_radeon_fence_wait));
+
+ if (parser->chunk_fence_idx != -1) {
+ chunk = (void __user*)(unsigned
long)parser->chunks_array[parser->chunk_fence_idx];
+ output.ring_token = parser->ib->fence->ring;
+ output.fence_token = parser->ib->fence->seq;
+ /* FIXME: What do I do about an error here? */
+ DRM_COPY_TO_USER(chunk,
+ &output,
+ sizeof(struct drm_radeon_fence_wait));
+ }
+}
+
/**
* cs_parser_fini() - clean parser states
* @parser: parser structure holding parsing context.
diff --git a/drivers/gpu/drm/radeon/radeon_fence.c
b/drivers/gpu/drm/radeon/radeon_fence.c
index 85893c3..50bb054 100644
--- a/drivers/gpu/drm/radeon/radeon_fence.c
+++ b/drivers/gpu/drm/radeon/radeon_fence.c
@@ -356,6 +356,22 @@ int radeon_fence_wait_value(struct radeon_device *rdev,
int ring,
return r;
}
+int radeon_fence_wait_value_ioctl(struct drm_device *dev, void *data,
+ struct drm_file *filp)
+{
+ struct radeon_device *rdev = dev->dev_private;
+ struct drm_radeon_fence_wait *args = data;
+ int r;
+
+ r = radeon_fence_wait_value(rdev,
+ args->ring_token,
+ args->fence_token,
+ usecs_to_jiffies(args->timeout_usec));
+ if (r > 0)
+ r = 0;
+
+ return r;
+}
struct radeon_fence *radeon_fence_ref(struct radeon_fence *fence)
{
kref_get(&fence->kref);
diff --git a/drivers/gpu/drm/radeon/radeon_kms.c
b/drivers/gpu/drm/radeon/radeon_kms.c
index d335288..a52db06 100644
--- a/drivers/gpu/drm/radeon/radeon_kms.c
+++ b/drivers/gpu/drm/radeon/radeon_kms.c
@@ -496,5 +496,6 @@ struct drm_ioctl_desc radeon_ioctls_kms[] = {
DRM_IOCTL_DEF_DRV(RADEON_GEM_GET_TILING, radeon_gem_get_tiling_ioctl,
DRM_AUTH|DRM_UNLOCKED),
DRM_IOCTL_DEF_DRV(RADEON_GEM_BUSY, radeon_gem_busy_ioctl,
DRM_AUTH|DRM_UNLOCKED),
DRM_IOCTL_DEF_DRV(RADEON_GEM_VA, radeon_gem_va_ioctl,
DRM_AUTH|DRM_UNLOCKED),
+ DRM_IOCTL_DEF_DRV(RADEON_FENCE_WAIT, radeon_fence_wait_value_ioctl,
DRM_AUTH|DRM_UNLOCKED),
};
int radeon_max_kms_ioctl = DRM_ARRAY_SIZE(radeon_ioctls_kms);
diff --git a/include/drm/radeon_drm.h b/include/drm/radeon_drm.h
index dd2e9cf..d81ce94 100644
--- a/include/drm/radeon_drm.h
+++ b/include/drm/radeon_drm.h
@@ -510,6 +510,7 @@ typedef struct {
#define DRM_RADEON_GEM_GET_TILING 0x29
#define DRM_RADEON_GEM_BUSY 0x2a
#define DRM_RADEON_GEM_VA 0x2b
+#define DRM_RADEON_FENCE_WAIT 0x2c
#define DRM_IOCTL_RADEON_CP_INIT DRM_IOW( DRM_COMMAND_BASE +
DRM_RADEON_CP_INIT, drm_radeon_init_t)
#define DRM_IOCTL_RADEON_CP_START DRM_IO( DRM_COMMAND_BASE +
DRM_RADEON_CP_START)
@@ -552,6 +553,7 @@ typedef struct {
#define DRM_IOCTL_RADEON_GEM_GET_TILING DRM_IOWR(DRM_COMMAND_BASE +
DRM_RADEON_GEM_GET_TILING, struct drm_radeon_gem_get_tiling)
#define DRM_IOCTL_RADEON_GEM_BUSY DRM_IOWR(DRM_COMMAND_BASE +
DRM_RADEON_GEM_BUSY, struct drm_radeon_gem_busy)
#define DRM_IOCTL_RADEON_GEM_VA DRM_IOWR(DRM_COMMAND_BASE +
DRM_RADEON_GEM_VA, struct drm_radeon_gem_va)
+#define DRM_IOCTL_RADEON_FENCE_WAIT DRM_IOWR(DRM_COMMAND_BASE +
DRM_RADEON_FENCE_WAIT, struct drm_radeon_fence_wait)
typedef struct drm_radeon_init {
enum {
@@ -906,6 +908,12 @@ struct drm_radeon_gem_va {
#define RADEON_CHUNK_ID_RELOCS 0x01
#define RADEON_CHUNK_ID_IB 0x02
#define RADEON_CHUNK_ID_FLAGS 0x03
+#define RADEON_CHUNK_ID_FENCE 0x04
+
+/* A RADEON_CHUNK_ID_FENCE is a struct drm_radeon_fence_wait. If the CS is
+ * accepted, the kernel will fill in the fence_token and ring_token elements
+ * such that userspace just needs to fill in timeout_usec and call the
+ * DRM_RADEON_FENCE_WAIT ioctl to wait for this CS to complete. */
/* The first dword of RADEON_CHUNK_ID_FLAGS is a uint32 of these flags: */
#define RADEON_CS_KEEP_TILING_FLAGS 0x01
@@ -967,4 +975,11 @@ struct drm_radeon_info {
uint64_t value;
};
+struct drm_radeon_fence_wait {
+ uint64_t fence_token;
+ uint64_t timeout_usec;
+ uint32_t ring_token;
+ uint32_t padding;
+};
+
#endif
--
1.7.6.4
