gpu: nvgpu: correct gpfifo size calculation

This change fixes up the calculation of gpfifo entries, to be
allocated depending on the ioctl used:

1) For the legacy ALLOC_GPFIFO ioctl, we preserve the calculation
of gpfifo entries within the kernel.

2) For the new ALLOC_GPFIFO_EX ioctl, we assume that userspace has
pre-calculated power-of-2 value. We process this value un-modified
and only verify that it is a valid power-of-2.

Bug 1795076

Change-Id: I8d2ddfdae40b02fe6b81e63dfd8857ad514a3dfd
Signed-off-by: Sachit Kadle <skadle@nvidia.com>
Reviewed-on: http://git-master/r/1220968
(cherry picked from commit c42396d9836e9b7ec73e0728f0c502b63aff70db)
Reviewed-on: http://git-master/r/1223937
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

1 files changed, 18 insertions, 5 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/channel_gk20a.c b/drivers/gpu/nvgpu/gk20a/channel_gk20a.c
index b846054d..6d4b4f60 100644
--- a/drivers/gpu/nvgpu/gk20a/channel_gk20a.c
+++ b/drivers/gpu/nvgpu/gk20a/channel_gk20a.c
@@ -1701,9 +1701,7 @@ int gk20a_alloc_channel_gpfifo(struct channel_gk20a *c,
         u32 gpfifo_size;
         int err = 0;
 
-        /* Kernel can insert one extra gpfifo entry before user submitted gpfifos
-           and another one after, for internal usage. Triple the requested size. */
-        gpfifo_size = roundup_pow_of_two(args->num_entries * 3);
+        gpfifo_size = args->num_entries;
 
         if (args->flags & NVGPU_ALLOC_GPFIFO_FLAGS_VPR_ENABLED)
                 c->vpr = true;
@@ -3404,6 +3402,10 @@ long gk20a_channel_ioctl(struct file *filp,
                 gk20a_idle(dev);
                 break;
         case NVGPU_IOCTL_CHANNEL_ALLOC_GPFIFO_EX:
+        {
+                struct nvgpu_alloc_gpfifo_ex_args *alloc_gpfifo_ex_args =
+                        (struct nvgpu_alloc_gpfifo_ex_args *)buf;
+
                 err = gk20a_busy(dev);
                 if (err) {
                         dev_err(dev,
@@ -3411,10 +3413,16 @@ long gk20a_channel_ioctl(struct file *filp,
                                 __func__, cmd);
                         break;
                 }
+
+                if (!is_power_of_2(alloc_gpfifo_ex_args->num_entries)) {
+                        err = -EINVAL;
+                        break;
+                }
                 err = gk20a_alloc_channel_gpfifo(ch,
                                 (struct nvgpu_alloc_gpfifo_ex_args *)buf);
                 gk20a_idle(dev);
                 break;
+        }
         case NVGPU_IOCTL_CHANNEL_ALLOC_GPFIFO:
         {
                 struct nvgpu_alloc_gpfifo_ex_args alloc_gpfifo_ex_args;
@@ -3432,8 +3440,13 @@ long gk20a_channel_ioctl(struct file *filp,
                 /* prepare new args structure */
                 memset(&alloc_gpfifo_ex_args, 0,
                                 sizeof(struct nvgpu_alloc_gpfifo_ex_args));
-                alloc_gpfifo_ex_args.num_entries =
-                                alloc_gpfifo_args->num_entries;
+                /*
+                 * Kernel can insert one extra gpfifo entry before user
+                 * submitted gpfifos and another one after, for internal usage.
+                 * Triple the requested size.
+                 */
+                alloc_gpfifo_ex_args.num_entries = roundup_pow_of_two(
+                                alloc_gpfifo_args->num_entries * 3);
                 alloc_gpfifo_ex_args.flags = alloc_gpfifo_args->flags;
 
                 err = gk20a_alloc_channel_gpfifo(ch, &alloc_gpfifo_ex_args);