gpu: nvgpu: Add semaphore based gk20a_channel_sync

Add semaphore implementation of the gk20a_channel_sync interface.

Each channel has one semaphore pool, which is mapped as read-write to
the channel vm. We allocate one or two semaphores from the pool for each
submit.

The first semaphore is only needed if we need to wait for an opaque sync
fd. In that case, we allocate the semaphore, and ask GPU to wait for
it's value to become 1 (semaphore acquire method).  We also queue a
kernel work that waits on the fence fd, and subsequently releases the
semaphore (sets its value to 1) so that the command buffer can proceed.

The second semaphore is used on every submit, and is used for work
completion tracking. The GPU sets its value to 1 when the command buffer
has been processed.

The channel jobs need to hold references to both semaphores so that
their backing semaphore pool slots are not reused while the job is in
flight. Therefore gk20a_channel_fence will keep a reference to the
semaphore that it represents (channel fences are stored in the job
structure). This means that we must diligently close and dup the
gk20a_channel_fence objects to avoid leaking semaphores.

Bug 1450122
Bug 1445450

Change-Id: Ib61091a1b7632fa36efe0289011040ef7c4ae8f8
Signed-off-by: Lauri Peltonen <lpeltonen@nvidia.com>
Reviewed-on: http://git-master/r/374844
GVS: Gerrit_Virtual_Submit
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>

1 files changed, 419 insertions, 5 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/channel_sync_gk20a.c b/drivers/gpu/nvgpu/gk20a/channel_sync_gk20a.c
index f91dd52d..677c4b49 100644
--- a/drivers/gpu/nvgpu/gk20a/channel_sync_gk20a.c
+++ b/drivers/gpu/nvgpu/gk20a/channel_sync_gk20a.c
@@ -19,6 +19,9 @@
 
 #include "channel_sync_gk20a.h"
 #include "gk20a.h"
+#include "semaphore_gk20a.h"
+#include "sync_gk20a.h"
+#include "mm_gk20a.h"
 
 #ifdef CONFIG_SYNC
 #include "../../../staging/android/sync.h"
@@ -74,7 +77,8 @@ bool gk20a_channel_syncpt_is_expired(struct gk20a_channel_sync *s,
 }
 
 int gk20a_channel_syncpt_wait_syncpt(struct gk20a_channel_sync *s, u32 id,
-                u32 thresh, struct priv_cmd_entry **entry)
+                u32 thresh, struct priv_cmd_entry **entry,
+                struct gk20a_channel_fence *fence)
 {
         struct gk20a_channel_syncpt *sp =
                 container_of(s, struct gk20a_channel_syncpt, ops);
@@ -99,11 +103,13 @@ int gk20a_channel_syncpt_wait_syncpt(struct gk20a_channel_sync *s, u32 id,
         add_wait_cmd(&wait_cmd->ptr[0], id, thresh);
 
         *entry = wait_cmd;
+        fence->valid = false;
         return 0;
 }
 
 int gk20a_channel_syncpt_wait_fd(struct gk20a_channel_sync *s, int fd,
-                       struct priv_cmd_entry **entry)
+                       struct priv_cmd_entry **entry,
+                       struct gk20a_channel_fence *fence)
 {
 #ifdef CONFIG_SYNC
         int i;
@@ -158,6 +164,7 @@ int gk20a_channel_syncpt_wait_fd(struct gk20a_channel_sync *s, int fd,
         sync_fence_put(sync_fence);
 
         *entry = wait_cmd;
+        fence->valid = false;
         return 0;
 #else
         return -ENODEV;
@@ -301,6 +308,7 @@ int gk20a_channel_syncpt_incr_user_syncpt(struct gk20a_channel_sync *s,
 }
 
 int gk20a_channel_syncpt_incr_user_fd(struct gk20a_channel_sync *s,
+                                      int wait_fence_fd,
                                       struct priv_cmd_entry **entry,
                                       struct gk20a_channel_fence *fence,
                                       bool wfi,
@@ -366,18 +374,424 @@ gk20a_channel_syncpt_create(struct channel_gk20a *c)
         sp->ops.set_min_eq_max          = gk20a_channel_syncpt_set_min_eq_max;
         sp->ops.destroy                 = gk20a_channel_syncpt_destroy;
 
-        sp->ops.syncpt_aggressive_destroy = true;
+        sp->ops.aggressive_destroy      = true;
 
         return &sp->ops;
 }
 #endif /* CONFIG_TEGRA_GK20A */
 
+struct gk20a_channel_semaphore {
+        struct gk20a_channel_sync ops;
+        struct channel_gk20a *c;
+
+        /* A semaphore pool owned by this channel. */
+        struct gk20a_semaphore_pool *pool;
+
+        /* A sync timeline that advances when gpu completes work. */
+        struct sync_timeline *timeline;
+};
+
+#ifdef CONFIG_SYNC
+struct wait_fence_work {
+        struct sync_fence_waiter waiter;
+        struct channel_gk20a *ch;
+        struct gk20a_semaphore *sema;
+};
+
+static void gk20a_channel_semaphore_launcher(
+                struct sync_fence *fence,
+                struct sync_fence_waiter *waiter)
+{
+        int err;
+        struct wait_fence_work *w =
+                container_of(waiter, struct wait_fence_work, waiter);
+        struct gk20a *g = w->ch->g;
+
+        gk20a_dbg_info("waiting for pre fence %p '%s'",
+                        fence, fence->name);
+        err = sync_fence_wait(fence, -1);
+        if (err < 0)
+                dev_err(&g->dev->dev, "error waiting pre-fence: %d\n", err);
+
+        gk20a_dbg_info(
+                  "wait completed (%d) for fence %p '%s', triggering gpu work",
+                  err, fence, fence->name);
+        sync_fence_put(fence);
+        gk20a_semaphore_release(w->sema);
+        gk20a_semaphore_put(w->sema);
+        kfree(w);
+}
+#endif
+
+static int add_sema_cmd(u32 *ptr, u64 sema, u32 payload,
+                        bool acquire, bool wfi)
+{
+        int i = 0;
+        /* semaphore_a */
+        ptr[i++] = 0x20010004;
+        /* offset_upper */
+        ptr[i++] = (sema >> 32) & 0xff;
+        /* semaphore_b */
+        ptr[i++] = 0x20010005;
+        /* offset */
+        ptr[i++] = sema & 0xffffffff;
+        /* semaphore_c */
+        ptr[i++] = 0x20010006;
+        /* payload */
+        ptr[i++] = payload;
+        if (acquire) {
+                /* semaphore_d */
+                ptr[i++] = 0x20010007;
+                /* operation: acq_geq, switch_en */
+                ptr[i++] = 0x4 | (0x1 << 12);
+        } else {
+                /* semaphore_d */
+                ptr[i++] = 0x20010007;
+                /* operation: release, wfi */
+                ptr[i++] = 0x2 | ((wfi ? 0x0 : 0x1) << 20);
+                /* non_stall_int */
+                ptr[i++] = 0x20010008;
+                /* ignored */
+                ptr[i++] = 0;
+        }
+        return i;
+}
+
+static int gk20a_channel_semaphore_wait_cpu(
+                struct gk20a_channel_sync *s,
+                struct gk20a_channel_fence *fence,
+                int timeout)
+{
+        int remain;
+        struct gk20a_channel_semaphore *sp =
+                container_of(s, struct gk20a_channel_semaphore, ops);
+        if (!fence->valid || WARN_ON(!fence->semaphore))
+                return 0;
+
+        remain = wait_event_interruptible_timeout(
+                sp->c->semaphore_wq,
+                !gk20a_semaphore_is_acquired(fence->semaphore),
+                timeout);
+        if (remain == 0 && gk20a_semaphore_is_acquired(fence->semaphore))
+                return -ETIMEDOUT;
+        else if (remain < 0)
+                return remain;
+        return 0;
+}
+
+static bool gk20a_channel_semaphore_is_expired(
+                struct gk20a_channel_sync *s,
+                struct gk20a_channel_fence *fence)
+{
+        bool expired;
+        struct gk20a_channel_semaphore *sp =
+                container_of(s, struct gk20a_channel_semaphore, ops);
+        if (!fence->valid || WARN_ON(!fence->semaphore))
+                return true;
+
+        expired = !gk20a_semaphore_is_acquired(fence->semaphore);
+        if (expired)
+                gk20a_sync_timeline_signal(sp->timeline);
+        return expired;
+}
+
+static int gk20a_channel_semaphore_wait_syncpt(
+                struct gk20a_channel_sync *s, u32 id,
+                u32 thresh, struct priv_cmd_entry **entry,
+                struct gk20a_channel_fence *fence)
+{
+        struct gk20a_channel_semaphore *sema =
+                container_of(s, struct gk20a_channel_semaphore, ops);
+        struct device *dev = dev_from_gk20a(sema->c->g);
+        gk20a_err(dev, "trying to use syncpoint synchronization");
+        return -ENODEV;
+}
+
+static int gk20a_channel_semaphore_wait_fd(
+                struct gk20a_channel_sync *s, int fd,
+                struct priv_cmd_entry **entry,
+                struct gk20a_channel_fence *fence)
+{
+        struct gk20a_channel_semaphore *sema =
+                container_of(s, struct gk20a_channel_semaphore, ops);
+        struct channel_gk20a *c = sema->c;
+#ifdef CONFIG_SYNC
+        struct sync_fence *sync_fence;
+        struct priv_cmd_entry *wait_cmd = NULL;
+        struct wait_fence_work *w;
+        int written;
+        int err;
+        u64 va;
+
+        sync_fence = gk20a_sync_fence_fdget(fd);
+        if (!sync_fence)
+                return -EINVAL;
+
+        w = kzalloc(sizeof(*w), GFP_KERNEL);
+        if (!w) {
+                err = -ENOMEM;
+                goto fail;
+        }
+        sync_fence_waiter_init(&w->waiter, gk20a_channel_semaphore_launcher);
+        w->ch = c;
+        w->sema = gk20a_semaphore_alloc(sema->pool);
+        if (!w->sema) {
+                gk20a_err(dev_from_gk20a(c->g), "ran out of semaphores");
+                err = -EAGAIN;
+                goto fail;
+        }
+
+        gk20a_channel_alloc_priv_cmdbuf(c, 8, &wait_cmd);
+        if (wait_cmd == NULL) {
+                gk20a_err(dev_from_gk20a(c->g),
+                                "not enough priv cmd buffer space");
+                err = -EAGAIN;
+                goto fail;
+        }
+
+        va = gk20a_semaphore_gpu_va(w->sema, c->vm);
+        /* GPU unblocked when when the semaphore value becomes 1. */
+        written = add_sema_cmd(wait_cmd->ptr, va, 1, true, false);
+        WARN_ON(written != wait_cmd->size);
+        sync_fence_wait_async(sync_fence, &w->waiter);
+
+        *entry = wait_cmd;
+        return 0;
+fail:
+        if (w && w->sema)
+                gk20a_semaphore_put(w->sema);
+        kfree(w);
+        sync_fence_put(sync_fence);
+        return err;
+#else
+        gk20a_err(dev_from_gk20a(c->g),
+                  "trying to use sync fds with CONFIG_SYNC disabled");
+        return -ENODEV;
+#endif
+}
+
+static int __gk20a_channel_semaphore_incr(
+                struct gk20a_channel_sync *s, bool wfi_cmd,
+                struct priv_cmd_entry **entry,
+                struct gk20a_channel_fence *fence)
+{
+        u64 va;
+        int incr_cmd_size;
+        int written;
+        struct priv_cmd_entry *incr_cmd = NULL;
+        struct gk20a_channel_semaphore *sp =
+                container_of(s, struct gk20a_channel_semaphore, ops);
+        struct channel_gk20a *c = sp->c;
+        struct gk20a_semaphore *semaphore;
+
+        semaphore = gk20a_semaphore_alloc(sp->pool);
+        if (!semaphore) {
+                gk20a_err(dev_from_gk20a(c->g),
+                                "ran out of semaphores");
+                return -EAGAIN;
+        }
+
+        incr_cmd_size = 10;
+        gk20a_channel_alloc_priv_cmdbuf(c, incr_cmd_size, &incr_cmd);
+        if (incr_cmd == NULL) {
+                gk20a_err(dev_from_gk20a(c->g),
+                                "not enough priv cmd buffer space");
+                gk20a_semaphore_put(semaphore);
+                return -EAGAIN;
+        }
+
+        /* Release the completion semaphore. */
+        va = gk20a_semaphore_gpu_va(semaphore, c->vm);
+        written = add_sema_cmd(incr_cmd->ptr, va, 1, false, wfi_cmd);
+        WARN_ON(written != incr_cmd_size);
+
+        fence->valid = true;
+        fence->wfi = wfi_cmd;
+        fence->semaphore = semaphore;
+        *entry = incr_cmd;
+        return 0;
+}
+
+static int gk20a_channel_semaphore_incr_wfi(
+                struct gk20a_channel_sync *s,
+                struct priv_cmd_entry **entry,
+                struct gk20a_channel_fence *fence)
+{
+        return __gk20a_channel_semaphore_incr(s,
+                        true /* wfi */,
+                        entry, fence);
+}
+
+static int gk20a_channel_semaphore_incr(
+                struct gk20a_channel_sync *s,
+                struct priv_cmd_entry **entry,
+                struct gk20a_channel_fence *fence)
+{
+        /* Don't put wfi cmd to this one since we're not returning
+         * a fence to user space. */
+        return __gk20a_channel_semaphore_incr(s, false /* no wfi */,
+                                              entry, fence);
+}
+
+static int gk20a_channel_semaphore_incr_user_syncpt(
+                struct gk20a_channel_sync *s,
+                struct priv_cmd_entry **entry,
+                struct gk20a_channel_fence *fence,
+                bool wfi,
+                u32 *id, u32 *thresh)
+{
+        struct gk20a_channel_semaphore *sema =
+                container_of(s, struct gk20a_channel_semaphore, ops);
+        struct device *dev = dev_from_gk20a(sema->c->g);
+        gk20a_err(dev, "trying to use syncpoint synchronization");
+        return -ENODEV;
+}
+
+static int gk20a_channel_semaphore_incr_user_fd(
+                struct gk20a_channel_sync *s,
+                int wait_fence_fd,
+                struct priv_cmd_entry **entry,
+                struct gk20a_channel_fence *fence,
+                bool wfi,
+                int *fd)
+{
+        struct gk20a_channel_semaphore *sema =
+                container_of(s, struct gk20a_channel_semaphore, ops);
+#ifdef CONFIG_SYNC
+        struct sync_fence *dependency = NULL;
+        int err;
+
+        err = __gk20a_channel_semaphore_incr(s, wfi,
+                                             entry, fence);
+        if (err)
+                return err;
+
+        if (wait_fence_fd >= 0) {
+                dependency = gk20a_sync_fence_fdget(wait_fence_fd);
+                if (!dependency)
+                        return -EINVAL;
+        }
+
+        *fd = gk20a_sync_fence_create(sema->timeline, fence->semaphore,
+                                      dependency, "fence");
+        if (*fd < 0) {
+                if (dependency)
+                        sync_fence_put(dependency);
+                return *fd;
+        }
+        return 0;
+#else
+        gk20a_err(dev_from_gk20a(sema->c->g),
+                  "trying to use sync fds with CONFIG_SYNC disabled");
+        return -ENODEV;
+#endif
+}
+
+static void gk20a_channel_semaphore_set_min_eq_max(struct gk20a_channel_sync *s)
+{
+        /* Nothing to do. */
+}
+
+static void gk20a_channel_semaphore_destroy(struct gk20a_channel_sync *s)
+{
+        struct gk20a_channel_semaphore *sema =
+                container_of(s, struct gk20a_channel_semaphore, ops);
+        if (sema->timeline)
+                gk20a_sync_timeline_destroy(sema->timeline);
+        if (sema->pool) {
+                gk20a_semaphore_pool_unmap(sema->pool, sema->c->vm);
+                gk20a_semaphore_pool_put(sema->pool);
+        }
+        kfree(sema);
+}
+
+static struct gk20a_channel_sync *
+gk20a_channel_semaphore_create(struct channel_gk20a *c)
+{
+        int err;
+        int asid = -1;
+        struct gk20a_channel_semaphore *sema;
+        char pool_name[20];
+
+        if (WARN_ON(!c->vm))
+                return NULL;
+
+        sema = kzalloc(sizeof(*sema), GFP_KERNEL);
+        if (!sema)
+                return NULL;
+        sema->c = c;
+
+        if (c->vm->as_share)
+                asid = c->vm->as_share->id;
+
+        /* A pool of 256 semaphores fits into one 4k page. */
+        sprintf(pool_name, "semaphore_pool-%d", c->hw_chid);
+        sema->pool = gk20a_semaphore_pool_alloc(dev_from_gk20a(c->g),
+                                                pool_name, 256);
+        if (!sema->pool)
+                goto clean_up;
+
+        /* Map the semaphore pool to the channel vm. Map as read-write to the
+         * owner channel (all other channels should map as read only!). */
+        err = gk20a_semaphore_pool_map(sema->pool, c->vm, gk20a_mem_flag_none);
+        if (err)
+                goto clean_up;
+
+#ifdef CONFIG_SYNC
+        sema->timeline = gk20a_sync_timeline_create(
+                        "gk20a_ch%d_as%d", c->hw_chid, asid);
+        if (!sema->timeline)
+                goto clean_up;
+#endif
+        sema->ops.wait_cpu      = gk20a_channel_semaphore_wait_cpu;
+        sema->ops.is_expired    = gk20a_channel_semaphore_is_expired;
+        sema->ops.wait_syncpt   = gk20a_channel_semaphore_wait_syncpt;
+        sema->ops.wait_fd       = gk20a_channel_semaphore_wait_fd;
+        sema->ops.incr          = gk20a_channel_semaphore_incr;
+        sema->ops.incr_wfi      = gk20a_channel_semaphore_incr_wfi;
+        sema->ops.incr_user_syncpt = gk20a_channel_semaphore_incr_user_syncpt;
+        sema->ops.incr_user_fd  = gk20a_channel_semaphore_incr_user_fd;
+        sema->ops.set_min_eq_max = gk20a_channel_semaphore_set_min_eq_max;
+        sema->ops.destroy       = gk20a_channel_semaphore_destroy;
+
+        /* Aggressively destroying the semaphore sync would cause overhead
+         * since the pool needs to be mapped to GMMU. */
+        sema->ops.aggressive_destroy = false;
+
+        return &sema->ops;
+clean_up:
+        gk20a_channel_semaphore_destroy(&sema->ops);
+        return NULL;
+}
+
 struct gk20a_channel_sync *gk20a_channel_sync_create(struct channel_gk20a *c)
 {
 #ifdef CONFIG_TEGRA_GK20A
         if (gk20a_platform_has_syncpoints(c->g->dev))
                 return gk20a_channel_syncpt_create(c);
 #endif
-        WARN_ON(1);
-        return NULL;
+        return gk20a_channel_semaphore_create(c);
+}
+
+static inline bool gk20a_channel_fence_is_closed(struct gk20a_channel_fence *f)
+{
+        if (f->valid || f->semaphore)
+                return false;
+        return true;
+}
+
+void gk20a_channel_fence_close(struct gk20a_channel_fence *f)
+{
+        if (f->semaphore)
+                gk20a_semaphore_put(f->semaphore);
+        memset(f, 0, sizeof(*f));
+}
+
+void gk20a_channel_fence_dup(struct gk20a_channel_fence *from,
+                             struct gk20a_channel_fence *to)
+{
+        WARN_ON(!gk20a_channel_fence_is_closed(to));
+        *to = *from;
+        if (to->semaphore)
+                gk20a_semaphore_get(to->semaphore);
 }