drm/panfrost: Implement per FD address spaces

Up until now, a single shared GPU address space was used. This is not
ideal as there's no protection between processes and doesn't work for
supporting the same GPU/CPU VA feature. Most importantly, this will
hopefully mitigate Alyssa's fear of WebGL, whatever that is.

Most of the changes here are moving struct drm_mm and struct
panfrost_mmu objects from the per device struct to the per FD struct.
The critical function is panfrost_mmu_as_get() which handles allocating
and switching the h/w address spaces.

There's 3 states an AS can be in: free, allocated, and in use. When a
job runs, it requests an address space and then marks it not in use when
job is complete(but stays assigned). The first time thru, we find a free
AS in the alloc_mask and assign the AS to the FD. Then the next time
thru, we most likely already have our AS and we just mark it in use with
a ref count. We need a ref count because we have multiple job slots. If
the job/FD doesn't have an AS assigned and there are no free ones, then
we pick an allocated one not in use from our LRU list and switch the AS
from the old FD to the new one.

Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Steven Price <steven.price@arm.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Acked-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190813150115.30338-1-robh@kernel.org

1 files changed, 20 insertions, 4 deletions

diff --git a/drivers/gpu/drm/panfrost/panfrost_device.h b/drivers/gpu/drm/panfrost/panfrost_device.h
index 4e5641db9c7e..f503c566e99f 100644
--- a/drivers/gpu/drm/panfrost/panfrost_device.h
+++ b/drivers/gpu/drm/panfrost/panfrost_device.h
@@ -5,6 +5,8 @@
 #ifndef __PANFROST_DEVICE_H__
 #define __PANFROST_DEVICE_H__
 
+#include <linux/atomic.h>
+#include <linux/io-pgtable.h>
 #include <linux/spinlock.h>
 #include <drm/drm_device.h>
 #include <drm/drm_mm.h>
@@ -63,9 +65,6 @@ struct panfrost_device {
 
 	spinlock_t hwaccess_lock;
 
-	struct drm_mm mm;
-	spinlock_t mm_lock;
-
 	void __iomem *iomem;
 	struct clk *clock;
 	struct clk *bus_clock;
@@ -74,7 +73,11 @@ struct panfrost_device {
 
 	struct panfrost_features features;
 
-	struct panfrost_mmu *mmu;
+	spinlock_t as_lock;
+	unsigned long as_in_use_mask;
+	unsigned long as_alloc_mask;
+	struct list_head as_lru_list;
+
 	struct panfrost_job_slot *js;
 
 	struct panfrost_job *jobs[NUM_JOB_SLOTS];
@@ -98,10 +101,23 @@ struct panfrost_device {
 	} devfreq;
 };
 
+struct panfrost_mmu {
+	struct io_pgtable_cfg pgtbl_cfg;
+	struct io_pgtable_ops *pgtbl_ops;
+	struct mutex lock;
+	int as;
+	atomic_t as_count;
+	struct list_head list;
+};
+
 struct panfrost_file_priv {
 	struct panfrost_device *pfdev;
 
 	struct drm_sched_entity sched_entity[NUM_JOB_SLOTS];
+
+	struct panfrost_mmu mmu;
+	struct drm_mm mm;
+	spinlock_t mm_lock;
 };
 
 static inline struct panfrost_device *to_panfrost_device(struct drm_device *ddev)