drm/i915: Separate GEM context construction and registration to userspace

In later patches, it became apparent that userspace can see a partially
constructed GEM context and begin using it before it was ready, to much
hilarity. Close this window of opportunity by lifting the registration of
the context with userspace (the insertion of the context into the filp's
idr) to the very end of the CONTEXT_CREATE ioctl.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190321140711.11190-1-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index d776d43707e0be72488a7fd1ea314afe53fcac91..c7cbc66945f080b05460fb1994dc1fce7104c8e6 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -337,15 +337,13 @@ static u32 default_desc_template(const struct drm_i915_private *i915,
 }
 
 static struct i915_gem_context *
-__create_hw_context(struct drm_i915_private *dev_priv,
-                   struct drm_i915_file_private *file_priv)
+__create_context(struct drm_i915_private *dev_priv)
 {
        struct i915_gem_context *ctx;
-       int ret;
        int i;
 
        ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
-       if (ctx == NULL)
+       if (!ctx)
                return ERR_PTR(-ENOMEM);
 
        kref_init(&ctx->ref);
@@ -362,29 +360,6 @@ __create_hw_context(struct drm_i915_private *dev_priv,
        INIT_LIST_HEAD(&ctx->handles_list);
        INIT_LIST_HEAD(&ctx->hw_id_link);
 
-       /* Default context will never have a file_priv */
-       ret = DEFAULT_CONTEXT_HANDLE;
-       if (file_priv) {
-               ret = idr_alloc(&file_priv->context_idr, ctx,
-                               DEFAULT_CONTEXT_HANDLE, 0, GFP_KERNEL);
-               if (ret < 0)
-                       goto err_lut;
-       }
-       ctx->user_handle = ret;
-
-       ctx->file_priv = file_priv;
-       if (file_priv) {
-               ctx->pid = get_task_pid(current, PIDTYPE_PID);
-               ctx->name = kasprintf(GFP_KERNEL, "%s[%d]/%x",
-                                     current->comm,
-                                     pid_nr(ctx->pid),
-                                     ctx->user_handle);
-               if (!ctx->name) {
-                       ret = -ENOMEM;
-                       goto err_pid;
-               }
-       }
-
        /* NB: Mark all slices as needing a remap so that when the context first
         * loads it will restore whatever remap state already exists. If there
         * is no remap info, it will be a NOP. */
@@ -401,25 +376,10 @@ __create_hw_context(struct drm_i915_private *dev_priv,
                ctx->hang_timestamp[i] = jiffies - CONTEXT_FAST_HANG_JIFFIES;
 
        return ctx;
-
-err_pid:
-       put_pid(ctx->pid);
-       idr_remove(&file_priv->context_idr, ctx->user_handle);
-err_lut:
-       context_close(ctx);
-       return ERR_PTR(ret);
-}
-
-static void __destroy_hw_context(struct i915_gem_context *ctx,
-                                struct drm_i915_file_private *file_priv)
-{
-       idr_remove(&file_priv->context_idr, ctx->user_handle);
-       context_close(ctx);
 }
 
 static struct i915_gem_context *
-i915_gem_create_context(struct drm_i915_private *dev_priv,
-                       struct drm_i915_file_private *file_priv)
+i915_gem_create_context(struct drm_i915_private *dev_priv)
 {
        struct i915_gem_context *ctx;
 
@@ -428,18 +388,18 @@ i915_gem_create_context(struct drm_i915_private *dev_priv,
        /* Reap the most stale context */
        contexts_free_first(dev_priv);
 
-       ctx = __create_hw_context(dev_priv, file_priv);
+       ctx = __create_context(dev_priv);
        if (IS_ERR(ctx))
                return ctx;
 
        if (HAS_FULL_PPGTT(dev_priv)) {
                struct i915_hw_ppgtt *ppgtt;
 
-               ppgtt = i915_ppgtt_create(dev_priv, file_priv);
+               ppgtt = i915_ppgtt_create(dev_priv);
                if (IS_ERR(ppgtt)) {
                        DRM_DEBUG_DRIVER("PPGTT setup failed (%ld)\n",
                                         PTR_ERR(ppgtt));
-                       __destroy_hw_context(ctx, file_priv);
+                       context_close(ctx);
                        return ERR_CAST(ppgtt);
                }
 
@@ -475,7 +435,7 @@ i915_gem_context_create_gvt(struct drm_device *dev)
        if (ret)
                return ERR_PTR(ret);
 
-       ctx = i915_gem_create_context(to_i915(dev), NULL);
+       ctx = i915_gem_create_context(to_i915(dev));
        if (IS_ERR(ctx))
                goto out;
 
@@ -511,7 +471,7 @@ i915_gem_context_create_kernel(struct drm_i915_private *i915, int prio)
        struct i915_gem_context *ctx;
        int err;
 
-       ctx = i915_gem_create_context(i915, NULL);
+       ctx = i915_gem_create_context(i915);
        if (IS_ERR(ctx))
                return ctx;
 
@@ -625,25 +585,74 @@ static int context_idr_cleanup(int id, void *p, void *data)
        return 0;
 }
 
+static int gem_context_register(struct i915_gem_context *ctx,
+                               struct drm_i915_file_private *fpriv)
+{
+       int ret;
+
+       ctx->file_priv = fpriv;
+       if (ctx->ppgtt)
+               ctx->ppgtt->vm.file = fpriv;
+
+       ctx->pid = get_task_pid(current, PIDTYPE_PID);
+       ctx->name = kasprintf(GFP_KERNEL, "%s[%d]",
+                             current->comm, pid_nr(ctx->pid));
+       if (!ctx->name) {
+               ret = -ENOMEM;
+               goto err_pid;
+       }
+
+       /* And finally expose ourselves to userspace via the idr */
+       ret = idr_alloc(&fpriv->context_idr, ctx,
+                       DEFAULT_CONTEXT_HANDLE, 0, GFP_KERNEL);
+       if (ret < 0)
+               goto err_name;
+
+       ctx->user_handle = ret;
+
+       return 0;
+
+err_name:
+       kfree(fetch_and_zero(&ctx->name));
+err_pid:
+       put_pid(fetch_and_zero(&ctx->pid));
+       return ret;
+}
+
 int i915_gem_context_open(struct drm_i915_private *i915,
                          struct drm_file *file)
 {
        struct drm_i915_file_private *file_priv = file->driver_priv;
        struct i915_gem_context *ctx;
+       int err;
 
        idr_init(&file_priv->context_idr);
 
        mutex_lock(&i915->drm.struct_mutex);
-       ctx = i915_gem_create_context(i915, file_priv);
-       mutex_unlock(&i915->drm.struct_mutex);
+
+       ctx = i915_gem_create_context(i915);
        if (IS_ERR(ctx)) {
-               idr_destroy(&file_priv->context_idr);
-               return PTR_ERR(ctx);
+               err = PTR_ERR(ctx);
+               goto err;
        }
 
+       err = gem_context_register(ctx, file_priv);
+       if (err)
+               goto err_ctx;
+
+       GEM_BUG_ON(ctx->user_handle != DEFAULT_CONTEXT_HANDLE);
        GEM_BUG_ON(i915_gem_context_is_kernel(ctx));
 
+       mutex_unlock(&i915->drm.struct_mutex);
+
        return 0;
+
+err_ctx:
+       context_close(ctx);
+err:
+       mutex_unlock(&i915->drm.struct_mutex);
+       idr_destroy(&file_priv->context_idr);
+       return PTR_ERR(ctx);
 }
 
 void i915_gem_context_close(struct drm_file *file)
@@ -835,17 +844,28 @@ int i915_gem_context_create_ioctl(struct drm_device *dev, void *data,
        if (ret)
                return ret;
 
-       ctx = i915_gem_create_context(i915, file_priv);
-       mutex_unlock(&dev->struct_mutex);
-       if (IS_ERR(ctx))
-               return PTR_ERR(ctx);
+       ctx = i915_gem_create_context(i915);
+       if (IS_ERR(ctx)) {
+               ret = PTR_ERR(ctx);
+               goto err_unlock;
+       }
 
-       GEM_BUG_ON(i915_gem_context_is_kernel(ctx));
+       ret = gem_context_register(ctx, file_priv);
+       if (ret)
+               goto err_ctx;
+
+       mutex_unlock(&dev->struct_mutex);
 
        args->ctx_id = ctx->user_handle;
        DRM_DEBUG("HW context %d created\n", args->ctx_id);
 
        return 0;
+
+err_ctx:
+       context_close(ctx);
+err_unlock:
+       mutex_unlock(&dev->struct_mutex);
+       return ret;
 }
 
 int i915_gem_context_destroy_ioctl(struct drm_device *dev, void *data,
@@ -870,7 +890,9 @@ int i915_gem_context_destroy_ioctl(struct drm_device *dev, void *data,
        if (ret)
                goto out;
 
-       __destroy_hw_context(ctx, file_priv);
+       idr_remove(&file_priv->context_idr, ctx->user_handle);
+       context_close(ctx);
+
        mutex_unlock(&dev->struct_mutex);
 
 out:

diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index b8055c8d4e719a2dca74eba377f740093cdbe3bd..b9e0e3a002239573a8560cc03e8551cf038aa20f 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -2069,8 +2069,7 @@ __hw_ppgtt_create(struct drm_i915_private *i915)
 }
 
 struct i915_hw_ppgtt *
-i915_ppgtt_create(struct drm_i915_private *i915,
-                 struct drm_i915_file_private *fpriv)
+i915_ppgtt_create(struct drm_i915_private *i915)
 {
        struct i915_hw_ppgtt *ppgtt;
 
@@ -2078,8 +2077,6 @@ i915_ppgtt_create(struct drm_i915_private *i915,
        if (IS_ERR(ppgtt))
                return ppgtt;
 
-       ppgtt->vm.file = fpriv;
-
        trace_i915_ppgtt_create(&ppgtt->vm);
 
        return ppgtt;
@@ -2657,7 +2654,7 @@ int i915_gem_init_aliasing_ppgtt(struct drm_i915_private *i915)
        struct i915_hw_ppgtt *ppgtt;
        int err;
 
-       ppgtt = i915_ppgtt_create(i915, ERR_PTR(-EPERM));
+       ppgtt = i915_ppgtt_create(i915);
        if (IS_ERR(ppgtt))
                return PTR_ERR(ppgtt);
 

diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.h b/drivers/gpu/drm/i915/i915_gem_gtt.h
index 35f21a2ae36c6ab7fdc2a20215afeaa1053eff02..b76ab4c2a0e6fcbb3f8f8b2b6515316b223876f6 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_gtt.h
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.h
@@ -603,15 +603,17 @@ int i915_gem_init_ggtt(struct drm_i915_private *dev_priv);
 void i915_ggtt_cleanup_hw(struct drm_i915_private *dev_priv);
 
 int i915_ppgtt_init_hw(struct drm_i915_private *dev_priv);
-void i915_ppgtt_release(struct kref *kref);
-struct i915_hw_ppgtt *i915_ppgtt_create(struct drm_i915_private *dev_priv,
-                                       struct drm_i915_file_private *fpriv);
+
+struct i915_hw_ppgtt *i915_ppgtt_create(struct drm_i915_private *dev_priv);
 void i915_ppgtt_close(struct i915_address_space *vm);
+void i915_ppgtt_release(struct kref *kref);
+
 static inline void i915_ppgtt_get(struct i915_hw_ppgtt *ppgtt)
 {
        if (ppgtt)
                kref_get(&ppgtt->ref);
 }
+
 static inline void i915_ppgtt_put(struct i915_hw_ppgtt *ppgtt)
 {
        if (ppgtt)

diff --git a/drivers/gpu/drm/i915/selftests/huge_pages.c b/drivers/gpu/drm/i915/selftests/huge_pages.c
index 2e1db30af477b0300ef6d00d4bb4b7454a832188..1f419fb094f4024585fccd8ff178bd46aac18b36 100644 (file)
--- a/drivers/gpu/drm/i915/selftests/huge_pages.c
+++ b/drivers/gpu/drm/i915/selftests/huge_pages.c
@@ -1713,7 +1713,7 @@ int i915_gem_huge_page_mock_selftests(void)
        mkwrite_device_info(dev_priv)->ppgtt_size = 48;
 
        mutex_lock(&dev_priv->drm.struct_mutex);
-       ppgtt = i915_ppgtt_create(dev_priv, ERR_PTR(-ENODEV));
+       ppgtt = i915_ppgtt_create(dev_priv);
        if (IS_ERR(ppgtt)) {
                err = PTR_ERR(ppgtt);
                goto out_unlock;

diff --git a/drivers/gpu/drm/i915/selftests/i915_gem_context.c b/drivers/gpu/drm/i915/selftests/i915_gem_context.c
index a172dbd9cb9e49c86d82a8a782e7df486a66d0a8..ab2aa32fd01964f48697239ec67a4aa8737ef6dd 100644 (file)
--- a/drivers/gpu/drm/i915/selftests/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/selftests/i915_gem_context.c
@@ -76,7 +76,7 @@ static int live_nop_switch(void *arg)
        }
 
        for (n = 0; n < nctx; n++) {
-               ctx[n] = i915_gem_create_context(i915, file->driver_priv);
+               ctx[n] = live_context(i915, file);
                if (IS_ERR(ctx[n])) {
                        err = PTR_ERR(ctx[n]);
                        goto out_unlock;
@@ -513,7 +513,7 @@ static int igt_ctx_exec(void *arg)
                struct i915_gem_context *ctx;
                unsigned int id;
 
-               ctx = i915_gem_create_context(i915, file->driver_priv);
+               ctx = live_context(i915, file);
                if (IS_ERR(ctx)) {
                        err = PTR_ERR(ctx);
                        goto out_unlock;
@@ -962,7 +962,7 @@ __igt_ctx_sseu(struct drm_i915_private *i915,
 
        mutex_lock(&i915->drm.struct_mutex);
 
-       ctx = i915_gem_create_context(i915, file->driver_priv);
+       ctx = live_context(i915, file);
        if (IS_ERR(ctx)) {
                ret = PTR_ERR(ctx);
                goto out_unlock;
@@ -1072,7 +1072,7 @@ static int igt_ctx_readonly(void *arg)
        if (err)
                goto out_unlock;
 
-       ctx = i915_gem_create_context(i915, file->driver_priv);
+       ctx = live_context(i915, file);
        if (IS_ERR(ctx)) {
                err = PTR_ERR(ctx);
                goto out_unlock;
@@ -1397,13 +1397,13 @@ static int igt_vm_isolation(void *arg)
        if (err)
                goto out_unlock;
 
-       ctx_a = i915_gem_create_context(i915, file->driver_priv);
+       ctx_a = live_context(i915, file);
        if (IS_ERR(ctx_a)) {
                err = PTR_ERR(ctx_a);
                goto out_unlock;
        }
 
-       ctx_b = i915_gem_create_context(i915, file->driver_priv);
+       ctx_b = live_context(i915, file);
        if (IS_ERR(ctx_b)) {
                err = PTR_ERR(ctx_b);
                goto out_unlock;

diff --git a/drivers/gpu/drm/i915/selftests/i915_gem_gtt.c b/drivers/gpu/drm/i915/selftests/i915_gem_gtt.c
index 826fd51c331ee6deaae48e3b4bb9be39d5e52886..01084f6b4fb788a26a1c0bdd34bdafb585e52099 100644 (file)
--- a/drivers/gpu/drm/i915/selftests/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/selftests/i915_gem_gtt.c
@@ -1010,7 +1010,7 @@ static int exercise_ppgtt(struct drm_i915_private *dev_priv,
                return PTR_ERR(file);
 
        mutex_lock(&dev_priv->drm.struct_mutex);
-       ppgtt = i915_ppgtt_create(dev_priv, file->driver_priv);
+       ppgtt = i915_ppgtt_create(dev_priv);
        if (IS_ERR(ppgtt)) {
                err = PTR_ERR(ppgtt);
                goto out_unlock;

diff --git a/drivers/gpu/drm/i915/selftests/mock_context.c b/drivers/gpu/drm/i915/selftests/mock_context.c
index 8efa6892c6cd96481d31effb5296e4e41d320962..ad3875b01722dc3387fdfbee6663b20cc6b5bd98 100644 (file)
--- a/drivers/gpu/drm/i915/selftests/mock_context.c
+++ b/drivers/gpu/drm/i915/selftests/mock_context.c
@@ -88,9 +88,24 @@ void mock_init_contexts(struct drm_i915_private *i915)
 struct i915_gem_context *
 live_context(struct drm_i915_private *i915, struct drm_file *file)
 {
+       struct i915_gem_context *ctx;
+       int err;
+
        lockdep_assert_held(&i915->drm.struct_mutex);
 
-       return i915_gem_create_context(i915, file->driver_priv);
+       ctx = i915_gem_create_context(i915);
+       if (IS_ERR(ctx))
+               return ctx;
+
+       err = gem_context_register(ctx, file->driver_priv);
+       if (err)
+               goto err_ctx;
+
+       return ctx;
+
+err_ctx:
+       context_close(ctx);
+       return ERR_PTR(err);
 }
 
 struct i915_gem_context *