gpu: nvgpu: avoid double mapping of usermode mmap region

gk20a_pm_runtime_suspend can fail and invoke gk20a_pm_finalize_poweron
that can cause double mapping of the usermode mmap region via
io_remap_pfn_range(). Avoid this by using a boolean variable to track
whether the region is already mapped.

Bug 2707416
Bug 200582208

Change-Id: I4d8cbe427400a5b986348a19af145367cc08ffc6
Signed-off-by: Debarshi Dutta <ddutta@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/2229312
Reviewed-on: https://git-master.nvidia.com/r/c/linux-nvgpu/+/2283801
Reviewed-by: Kajetan Dutka <kdutka@nvidia.com>
Reviewed-by: Thomas Fleury <tfleury@nvidia.com>
Reviewed-by: Amulya Yarlagadda <ayarlagadda@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: Kajetan Dutka <kdutka@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

1 files changed, 14 insertions, 2 deletions

diff --git a/drivers/gpu/nvgpu/os/linux/ioctl_ctrl.c b/drivers/gpu/nvgpu/os/linux/ioctl_ctrl.c
index 9b4f50a5..dfa9edf3 100644
--- a/drivers/gpu/nvgpu/os/linux/ioctl_ctrl.c
+++ b/drivers/gpu/nvgpu/os/linux/ioctl_ctrl.c
@@ -60,6 +60,7 @@ struct gk20a_ctrl_priv {
         struct {
                 struct vm_area_struct *vma;
                 unsigned long flags;
+                bool vma_mapped;
         } usermode_vma;
 };
 
@@ -1925,6 +1926,7 @@ static void usermode_vma_close(struct vm_area_struct *vma)
 
         nvgpu_mutex_acquire(&l->ctrl.privs_lock);
         priv->usermode_vma.vma = NULL;
+        priv->usermode_vma.vma_mapped = false;
         nvgpu_mutex_release(&l->ctrl.privs_lock);
 }
 
@@ -1974,6 +1976,7 @@ int gk20a_ctrl_dev_mmap(struct file *filp, struct vm_area_struct *vma)
                 priv->usermode_vma.vma = vma;
                 priv->usermode_vma.flags = vma->vm_flags;
                 vma->vm_private_data = priv;
+                priv->usermode_vma.vma_mapped = true;
         }
         nvgpu_mutex_release(&l->ctrl.privs_lock);
 
@@ -1988,6 +1991,7 @@ static void alter_usermode_mapping(struct gk20a *g,
 {
         struct nvgpu_os_linux *l = nvgpu_os_linux_from_gk20a(g);
         struct vm_area_struct *vma = priv->usermode_vma.vma;
+        bool vma_mapped = priv->usermode_vma.vma_mapped;
         u64 addr;
         int err;
 
@@ -2000,14 +2004,20 @@ static void alter_usermode_mapping(struct gk20a *g,
 
         down_write(&vma->vm_mm->mmap_sem);
 
-        if (poweroff) {
+        /*
+         * This is a no-op for the below cases
+         * a) poweroff and !vma_mapped - > do nothing as no map exists
+         * b) !poweroff and vmap_mapped -> do nothing as already mapped
+         */
+        if (poweroff && vma_mapped) {
                 err = zap_vma_ptes(vma, vma->vm_start, SZ_4K);
                 if (err == 0) {
                         vma->vm_flags = VM_NONE;
+                        priv->usermode_vma.vma_mapped = false;
                 } else {
                         nvgpu_err(g, "can't remove usermode mapping");
                 }
-        } else {
+        } else if (!poweroff && !vma_mapped) {
                 vma->vm_flags = priv->usermode_vma.flags;
                 err = io_remap_pfn_range(vma, vma->vm_start,
                                 addr >> PAGE_SHIFT,
@@ -2015,6 +2025,8 @@ static void alter_usermode_mapping(struct gk20a *g,
                 if (err != 0) {
                         nvgpu_err(g, "can't restore usermode mapping");
                         vma->vm_flags = VM_NONE;
+                } else {
+                        priv->usermode_vma.vma_mapped = true;
                 }
         }