gpu: nvgpu: fix debugfs to disable big pages

After setting 'Y' in disable_bigpage, in native SMMU case,
we could still see 64K GMMU pages beeing used.

Fixed the following:
    - enforce disable_bigpage in nvgpu_vm_map
    - update GPU characteristics so that new clients know
      whether or not big pages are enabled. For instance
      this may affect how CUDA requests memory mapping.

JIRA EVLR-1694

Change-Id: I62841096add3bd798c5c11090054f82c8a2be832
Signed-off-by: Thomas Fleury <tfleury@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1532429
Reviewed-by: Richard Zhao <rizhao@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: svccoveritychecker <svccoveritychecker@nvidia.com>
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>

1 files changed, 43 insertions, 2 deletions

diff --git a/drivers/gpu/nvgpu/common/linux/debug.c b/drivers/gpu/nvgpu/common/linux/debug.c
index 36f142d7..7dce74d6 100644
--- a/drivers/gpu/nvgpu/common/linux/debug.c
+++ b/drivers/gpu/nvgpu/common/linux/debug.c
@@ -28,6 +28,7 @@
 
 #include <linux/debugfs.h>
 #include <linux/seq_file.h>
+#include <linux/uaccess.h>
 
 #include <nvgpu/debug.h>
 
@@ -173,6 +174,45 @@ void gk20a_debug_show_dump(struct gk20a *g, struct gk20a_debug_output *o)
         gk20a_debug_dump_all_channel_status_ramfc(g, o);
 }
 
+static ssize_t disable_bigpage_read(struct file *file, char __user *user_buf, size_t count, loff_t *ppos)
+{
+        char buf[3];
+        struct gk20a *g = file->private_data;
+
+        if (g->mm.disable_bigpage)
+                buf[0] = 'Y';
+        else
+                buf[0] = 'N';
+        buf[1] = '\n';
+        buf[2] = 0x00;
+        return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
+}
+
+static ssize_t disable_bigpage_write(struct file *file, const char __user *user_buf, size_t count, loff_t *ppos)
+{
+        char buf[32];
+        int buf_size;
+        bool bv;
+        struct gk20a *g = file->private_data;
+
+        buf_size = min(count, (sizeof(buf)-1));
+        if (copy_from_user(buf, user_buf, buf_size))
+                return -EFAULT;
+
+        if (strtobool(buf, &bv) == 0) {
+                g->mm.disable_bigpage = bv;
+                gk20a_init_gpu_characteristics(g);
+        }
+
+        return count;
+}
+
+static struct file_operations disable_bigpage_fops = {
+        .open =         simple_open,
+        .read =         disable_bigpage_read,
+        .write =        disable_bigpage_write,
+};
+
 static int railgate_residency_show(struct seq_file *s, void *data)
 {
         struct gk20a *g = s->private;
@@ -296,10 +336,11 @@ void gk20a_debug_init(struct gk20a *g, const char *debugfs_symlink)
                                         l->debugfs,
                                         &g->mm.bypass_smmu);
         l->debugfs_disable_bigpage =
-                        debugfs_create_bool("disable_bigpage",
+                        debugfs_create_file("disable_bigpage",
                                         S_IRUGO|S_IWUSR,
                                         l->debugfs,
-                                        &g->mm.disable_bigpage);
+                                        g,
+                                        &disable_bigpage_fops);
 
         l->debugfs_timeslice_low_priority_us =
                         debugfs_create_u32("timeslice_low_priority_us",