drm/amdkfd: Kmap event page for dGPUs

The events page must be accessible in user mode by the GPU and CPU
as well as in kernel mode by the CPU. On dGPUs user mode virtual
addresses are managed by the Thunk's GPU memory allocation code.
Therefore we can't allocate the memory in kernel mode like we do
on APUs. But KFD still needs to map the memory for kernel access.
To facilitate this, the Thunk provides the buffer handle of the
events page to KFD when creating the first event.

Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>

1 files changed, 29 insertions, 2 deletions

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_events.c b/drivers/gpu/drm/amd/amdkfd/kfd_events.c
index 6fb9c0d46d63..4890a90f1e44 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_events.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_events.c
@@ -52,6 +52,7 @@ struct kfd_event_waiter {
 struct kfd_signal_page {
 	uint64_t *kernel_address;
 	uint64_t __user *user_address;
+	bool need_to_free_pages;
 };
 
 
@@ -79,6 +80,7 @@ static struct kfd_signal_page *allocate_signal_page(struct kfd_process *p)
 	       KFD_SIGNAL_EVENT_LIMIT * 8);
 
 	page->kernel_address = backing_store;
+	page->need_to_free_pages = true;
 	pr_debug("Allocated new event signal page at %p, for process %p\n",
 			page, p);
 
@@ -269,8 +271,9 @@ static void shutdown_signal_page(struct kfd_process *p)
 	struct kfd_signal_page *page = p->signal_page;
 
 	if (page) {
-		free_pages((unsigned long)page->kernel_address,
-				get_order(KFD_SIGNAL_EVENT_LIMIT * 8));
+		if (page->need_to_free_pages)
+			free_pages((unsigned long)page->kernel_address,
+				   get_order(KFD_SIGNAL_EVENT_LIMIT * 8));
 		kfree(page);
 	}
 }
@@ -292,6 +295,30 @@ static bool event_can_be_cpu_signaled(const struct kfd_event *ev)
 	return ev->type == KFD_EVENT_TYPE_SIGNAL;
 }
 
+int kfd_event_page_set(struct kfd_process *p, void *kernel_address,
+		       uint64_t size)
+{
+	struct kfd_signal_page *page;
+
+	if (p->signal_page)
+		return -EBUSY;
+
+	page = kzalloc(sizeof(*page), GFP_KERNEL);
+	if (!page)
+		return -ENOMEM;
+
+	/* Initialize all events to unsignaled */
+	memset(kernel_address, (uint8_t) UNSIGNALED_EVENT_SLOT,
+	       KFD_SIGNAL_EVENT_LIMIT * 8);
+
+	page->kernel_address = kernel_address;
+
+	p->signal_page = page;
+	p->signal_mapped_size = size;
+
+	return 0;
+}
+
 int kfd_event_create(struct file *devkfd, struct kfd_process *p,
 		     uint32_t event_type, bool auto_reset, uint32_t node_id,
 		     uint32_t *event_id, uint32_t *event_trigger_data,