drm/amdkfd: Add available memory ioctl

Add a new KFD ioctl to return the largest possible memory size that
can be allocated as a buffer object using
kfd_ioctl_alloc_memory_of_gpu. It attempts to use exactly the same
accept/reject criteria as that function so that allocating a new
buffer object of the size returned by this new ioctl is guaranteed to
succeed, barring races with other allocating tasks.

This IOCTL will be used by libhsakmt:
https://www.mail-archive.com/amd-gfx@lists.freedesktop.org/msg75743.html

Signed-off-by: Daniel Phillips <Daniel.Phillips@amd.com>
Signed-off-by: David Yat Sin <David.YatSin@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 34 insertions, 0 deletions

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
index 1c7016958d6d..3bcf9bf29acb 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
@@ -65,6 +65,25 @@ static int kfd_char_dev_major = -1;
 static struct class *kfd_class;
 struct device *kfd_device;
 
+static inline struct kfd_process_device *kfd_lock_pdd_by_id(struct kfd_process *p, __u32 gpu_id)
+{
+	struct kfd_process_device *pdd;
+
+	mutex_lock(&p->mutex);
+	pdd = kfd_process_device_data_by_id(p, gpu_id);
+
+	if (pdd)
+		return pdd;
+
+	mutex_unlock(&p->mutex);
+	return NULL;
+}
+
+static inline void kfd_unlock_pdd(struct kfd_process_device *pdd)
+{
+	mutex_unlock(&pdd->process->mutex);
+}
+
 int kfd_chardev_init(void)
 {
 	int err = 0;
@@ -958,6 +977,19 @@ bool kfd_dev_is_large_bar(struct kfd_dev *dev)
 	return false;
 }
 
+static int kfd_ioctl_get_available_memory(struct file *filep,
+					  struct kfd_process *p, void *data)
+{
+	struct kfd_ioctl_get_available_memory_args *args = data;
+	struct kfd_process_device *pdd = kfd_lock_pdd_by_id(p, args->gpu_id);
+
+	if (!pdd)
+		return -EINVAL;
+	args->available = amdgpu_amdkfd_get_available_memory(pdd->dev->adev);
+	kfd_unlock_pdd(pdd);
+	return 0;
+}
+
 static int kfd_ioctl_alloc_memory_of_gpu(struct file *filep,
 					struct kfd_process *p, void *data)
 {
@@ -2648,6 +2680,8 @@ static const struct amdkfd_ioctl_desc amdkfd_ioctls[] = {
 	AMDKFD_IOCTL_DEF(AMDKFD_IOC_CRIU_OP,
 			kfd_ioctl_criu, KFD_IOC_FLAG_CHECKPOINT_RESTORE),
 
+	AMDKFD_IOCTL_DEF(AMDKFD_IOC_AVAILABLE_MEMORY,
+			kfd_ioctl_get_available_memory, 0),
 };
 
 #define AMDKFD_CORE_IOCTL_COUNT	ARRAY_SIZE(amdkfd_ioctls)