drm/xe: Avoid any races around ccs_mode update

Ensure that there are no drm clients when changing CCS mode.
Allow exec_queue creation only with enabled CCS engines.

v2: Rebase

Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Signed-off-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

diff --git a/drivers/gpu/drm/xe/xe_device.c b/drivers/gpu/drm/xe/xe_device.c
index 8423c817111bf77a9c2b55341a9a72a0f245b4a0..2e0b2e40d8f3b3c2bfe6db4510d69f57d98533f4 100644 (file)
--- a/drivers/gpu/drm/xe/xe_device.c
+++ b/drivers/gpu/drm/xe/xe_device.c
@@ -73,6 +73,10 @@ static int xe_file_open(struct drm_device *dev, struct drm_file *file)
        mutex_init(&xef->exec_queue.lock);
        xa_init_flags(&xef->exec_queue.xa, XA_FLAGS_ALLOC1);
 
+       spin_lock(&xe->clients.lock);
+       xe->clients.count++;
+       spin_unlock(&xe->clients.lock);
+
        file->driver_priv = xef;
        return 0;
 }
@@ -105,6 +109,10 @@ static void xe_file_close(struct drm_device *dev, struct drm_file *file)
        xa_destroy(&xef->vm.xa);
        mutex_destroy(&xef->vm.lock);
 
+       spin_lock(&xe->clients.lock);
+       xe->clients.count--;
+       spin_unlock(&xe->clients.lock);
+
        xe_drm_client_put(xef->client);
        kfree(xef);
 }
@@ -225,6 +233,7 @@ struct xe_device *xe_device_create(struct pci_dev *pdev,
        xe->info.force_execlist = xe_modparam.force_execlist;
 
        spin_lock_init(&xe->irq.lock);
+       spin_lock_init(&xe->clients.lock);
 
        init_waitqueue_head(&xe->ufence_wq);
 

diff --git a/drivers/gpu/drm/xe/xe_device_types.h b/drivers/gpu/drm/xe/xe_device_types.h
index 9a212dbdb8a4934cb9db9c829ad92ce2df0124d0..58442da2f6c5c88c54a26952cbc1bae2037ed9ba 100644 (file)
--- a/drivers/gpu/drm/xe/xe_device_types.h
+++ b/drivers/gpu/drm/xe/xe_device_types.h
@@ -310,6 +310,15 @@ struct xe_device {
                enum xe_sriov_mode __mode;
        } sriov;
 
+       /** @clients: drm clients info */
+       struct {
+               /** @lock: Protects drm clients info */
+               spinlock_t lock;
+
+               /** @count: number of drm clients */
+               u64 count;
+       } clients;
+
        /** @usm: unified memory state */
        struct {
                /** @asid: convert a ASID to VM */

diff --git a/drivers/gpu/drm/xe/xe_gt_ccs_mode.c b/drivers/gpu/drm/xe/xe_gt_ccs_mode.c
index 723cf77c830a1f461b2b7ad64ad620fc29d8119f..529fc286cd06c6d46bcfde3b39bcd0e0befb8b44 100644 (file)
--- a/drivers/gpu/drm/xe/xe_gt_ccs_mode.c
+++ b/drivers/gpu/drm/xe/xe_gt_ccs_mode.c
@@ -105,6 +105,7 @@ ccs_mode_store(struct device *kdev, struct device_attribute *attr,
               const char *buff, size_t count)
 {
        struct xe_gt *gt = kobj_to_gt(&kdev->kobj);
+       struct xe_device *xe = gt_to_xe(gt);
        u32 num_engines, num_slices;
        int ret;
 
@@ -123,12 +124,21 @@ ccs_mode_store(struct device *kdev, struct device_attribute *attr,
                return -EINVAL;
        }
 
+       /* CCS mode can only be updated when there are no drm clients */
+       spin_lock(&xe->clients.lock);
+       if (xe->clients.count) {
+               spin_unlock(&xe->clients.lock);
+               return -EBUSY;
+       }
+
        if (gt->ccs_mode != num_engines) {
                xe_gt_info(gt, "Setting compute mode to %d\n", num_engines);
                gt->ccs_mode = num_engines;
                xe_gt_reset_async(gt);
        }
 
+       spin_unlock(&xe->clients.lock);
+
        return count;
 }