Re: [RFC 01/10] drm/i915/vm_bind: Introduce VM_BIND ioctl

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On Tue, Jul 05, 2022 at 02:59:24AM -0700, Hellstrom, Thomas wrote:
Hi,


On Fri, 2022-07-01 at 15:50 -0700, Niranjana Vishwanathapura wrote:
Add VM_BIND and VM_UNBIND ioctls to bind/unbind a section of an
object at the specified GPU virtual addresses.

Add I915_PARAM_VM_BIND_VERSION to indicate version of VM_BIND feature
supported and I915_VM_CREATE_FLAGS_USE_VM_BIND for UMDs to select the
vm_bind mode of binding.

Signed-off-by: Niranjana Vishwanathapura
<niranjana.vishwanathapura@xxxxxxxxx>

Some comments on patch ordering. In order to ease reviews and to not
introduce unwanted surprises, could we

1) Add patches that introduce needed internal functionality /
refactoring / helpers.
2) Add patches that add enable intended user-space functionality, any
yet unsupported functionality disabled.
3) Add patches that introduce additional internal functionality /
refactoring / helpers.
4) Add patches that enable that additional functionality.

Fixes that are known at series submission time squashed before a
feature is enabled.


Thanks Thomas for the feedback.

Yah, makes sense.


---
 drivers/gpu/drm/i915/gem/i915_gem_context.c |  20 +-
 drivers/gpu/drm/i915/gem/i915_gem_context.h |  15 ++
 drivers/gpu/drm/i915/gt/intel_gtt.h         |   6 +
 drivers/gpu/drm/i915/i915_driver.c          |  30 +++
 drivers/gpu/drm/i915/i915_getparam.c        |   3 +
 include/uapi/drm/i915_drm.h                 | 192
+++++++++++++++++++-
 6 files changed, 248 insertions(+), 18 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c
b/drivers/gpu/drm/i915/gem/i915_gem_context.c
index dabdfe09f5e5..e3f5fbf2ac05 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
@@ -81,7 +81,6 @@

 #include "pxp/intel_pxp.h"

-#include "i915_file_private.h"
 #include "i915_gem_context.h"
 #include "i915_trace.h"
 #include "i915_user_extensions.h"
@@ -346,20 +345,6 @@ static int proto_context_register(struct
drm_i915_file_private *fpriv,
        return ret;
 }

-static struct i915_address_space *
-i915_gem_vm_lookup(struct drm_i915_file_private *file_priv, u32 id)
-{
-       struct i915_address_space *vm;
-
-       xa_lock(&file_priv->vm_xa);
-       vm = xa_load(&file_priv->vm_xa, id);
-       if (vm)
-               kref_get(&vm->ref);
-       xa_unlock(&file_priv->vm_xa);
-
-       return vm;
-}
-
 static int set_proto_ctx_vm(struct drm_i915_file_private *fpriv,
                            struct i915_gem_proto_context *pc,
                            const struct drm_i915_gem_context_param
*args)
@@ -1799,7 +1784,7 @@ int i915_gem_vm_create_ioctl(struct drm_device
*dev, void *data,
        if (!HAS_FULL_PPGTT(i915))
                return -ENODEV;

-       if (args->flags)
+       if (args->flags & I915_VM_CREATE_FLAGS_UNKNOWN)
                return -EINVAL;

        ppgtt = i915_ppgtt_create(to_gt(i915), 0);
@@ -1819,6 +1804,9 @@ int i915_gem_vm_create_ioctl(struct drm_device
*dev, void *data,
        if (err)
                goto err_put;

+       if (args->flags & I915_VM_CREATE_FLAGS_USE_VM_BIND)
+               ppgtt->vm.vm_bind_mode = true;
+
        GEM_BUG_ON(id == 0); /* reserved for invalid/unassigned ppgtt
*/
        args->vm_id = id;
        return 0;
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.h
b/drivers/gpu/drm/i915/gem/i915_gem_context.h
index e5b0f66ea1fe..723bf446c934 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context.h
@@ -12,6 +12,7 @@
 #include "gt/intel_context.h"

 #include "i915_drv.h"
+#include "i915_file_private.h"
 #include "i915_gem.h"
 #include "i915_scheduler.h"
 #include "intel_device_info.h"
@@ -139,6 +140,20 @@ int i915_gem_context_setparam_ioctl(struct
drm_device *dev, void *data,
 int i915_gem_context_reset_stats_ioctl(struct drm_device *dev, void
*data,
                                       struct drm_file *file);

+static inline struct i915_address_space *
+i915_gem_vm_lookup(struct drm_i915_file_private *file_priv, u32 id)
+{
+       struct i915_address_space *vm;
+
+       xa_lock(&file_priv->vm_xa);
+       vm = xa_load(&file_priv->vm_xa, id);
+       if (vm)
+               kref_get(&vm->ref);
+       xa_unlock(&file_priv->vm_xa);
+
+       return vm;
+}

Does this really need to be inlined?

+
 struct i915_gem_context *
 i915_gem_context_lookup(struct drm_i915_file_private *file_priv, u32
id);

diff --git a/drivers/gpu/drm/i915/gt/intel_gtt.h
b/drivers/gpu/drm/i915/gt/intel_gtt.h
index e639434e97fd..c812aa9708ae 100644
--- a/drivers/gpu/drm/i915/gt/intel_gtt.h
+++ b/drivers/gpu/drm/i915/gt/intel_gtt.h
@@ -271,6 +271,12 @@ struct i915_address_space {
        /* Skip pte rewrite on unbind for suspend. Protected by
@mutex */
        bool skip_pte_rewrite:1;

+       /**
+        * true: allow only vm_bind method of binding.
+        * false: allow only legacy execbuff method of binding.
+        */

Use proper kerneldoc. (Same holds for structure documentation across
the series).
Also please follow internal locking guidelines on documentation of
members that need protection with locks.


I just followed the documentation convention that was already there ;)
I think we need a prep patch in this series that adds kernel-doc for
these structures and then add new fields for vm_bind with proper
kernel-docs.

+       bool vm_bind_mode:1;
+
        u8 top;
        u8 pd_shift;
        u8 scratch_order;
diff --git a/drivers/gpu/drm/i915/i915_driver.c
b/drivers/gpu/drm/i915/i915_driver.c
index deb8a8b76965..ccf990dfd99b 100644
--- a/drivers/gpu/drm/i915/i915_driver.c
+++ b/drivers/gpu/drm/i915/i915_driver.c
@@ -1778,6 +1778,34 @@ i915_gem_reject_pin_ioctl(struct drm_device
*dev, void *data,
        return -ENODEV;
 }

+static int i915_gem_vm_bind_ioctl(struct drm_device *dev, void
*data,
+                                 struct drm_file *file)
+{
+       struct drm_i915_gem_vm_bind *args = data;
+       struct i915_address_space *vm;
+
+       vm = i915_gem_vm_lookup(file->driver_priv, args->vm_id);
+       if (unlikely(!vm))
+               return -ENOENT;
+
+       i915_vm_put(vm);
+       return -EINVAL;
+}
+
+static int i915_gem_vm_unbind_ioctl(struct drm_device *dev, void
*data,
+                                   struct drm_file *file)
+{
+       struct drm_i915_gem_vm_unbind *args = data;
+       struct i915_address_space *vm;
+
+       vm = i915_gem_vm_lookup(file->driver_priv, args->vm_id);
+       if (unlikely(!vm))
+               return -ENOENT;
+
+       i915_vm_put(vm);
+       return -EINVAL;
+}
+

Move these functions to the file of the actual implementation?


Yah, makes sense.

 static const struct drm_ioctl_desc i915_ioctls[] = {
        DRM_IOCTL_DEF_DRV(I915_INIT, drm_noop,
DRM_AUTH|DRM_MASTER|DRM_ROOT_ONLY),
        DRM_IOCTL_DEF_DRV(I915_FLUSH, drm_noop, DRM_AUTH),
@@ -1838,6 +1866,8 @@ static const struct drm_ioctl_desc
i915_ioctls[] = {
        DRM_IOCTL_DEF_DRV(I915_QUERY, i915_query_ioctl,
DRM_RENDER_ALLOW),
        DRM_IOCTL_DEF_DRV(I915_GEM_VM_CREATE,
i915_gem_vm_create_ioctl, DRM_RENDER_ALLOW),
        DRM_IOCTL_DEF_DRV(I915_GEM_VM_DESTROY,
i915_gem_vm_destroy_ioctl, DRM_RENDER_ALLOW),
+       DRM_IOCTL_DEF_DRV(I915_GEM_VM_BIND, i915_gem_vm_bind_ioctl,
DRM_RENDER_ALLOW),
+       DRM_IOCTL_DEF_DRV(I915_GEM_VM_UNBIND,
i915_gem_vm_unbind_ioctl, DRM_RENDER_ALLOW),
 };

 /*
diff --git a/drivers/gpu/drm/i915/i915_getparam.c
b/drivers/gpu/drm/i915/i915_getparam.c
index 6fd15b39570c..c1d53febc5de 100644
--- a/drivers/gpu/drm/i915/i915_getparam.c
+++ b/drivers/gpu/drm/i915/i915_getparam.c
@@ -175,6 +175,9 @@ int i915_getparam_ioctl(struct drm_device *dev,
void *data,
        case I915_PARAM_PERF_REVISION:
                value = i915_perf_ioctl_version();
                break;
+       case I915_PARAM_VM_BIND_VERSION:
+               value = GRAPHICS_VER(i915) >= 12 ? 1 : 0;
+               break;
        default:
                DRM_DEBUG("Unknown parameter %d\n", param->param);
                return -EINVAL;
diff --git a/include/uapi/drm/i915_drm.h
b/include/uapi/drm/i915_drm.h
index 3e78a00220ea..26cca49717f8 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -470,6 +470,8 @@ typedef struct _drm_i915_sarea {
 #define DRM_I915_GEM_VM_CREATE         0x3a
 #define DRM_I915_GEM_VM_DESTROY                0x3b
 #define DRM_I915_GEM_CREATE_EXT                0x3c
+#define DRM_I915_GEM_VM_BIND           0x3d
+#define DRM_I915_GEM_VM_UNBIND         0x3e
 /* Must be kept compact -- no holes */

 #define DRM_IOCTL_I915_INIT            DRM_IOW( DRM_COMMAND_BASE +
DRM_I915_INIT, drm_i915_init_t)
@@ -534,6 +536,8 @@ typedef struct _drm_i915_sarea {
 #define
DRM_IOCTL_I915_QUERY                   DRM_IOWR(DRM_COMMAND_BASE +
DRM_I915_QUERY, struct drm_i915_query)
 #define DRM_IOCTL_I915_GEM_VM_CREATE   DRM_IOWR(DRM_COMMAND_BASE +
DRM_I915_GEM_VM_CREATE, struct drm_i915_gem_vm_control)
 #define DRM_IOCTL_I915_GEM_VM_DESTROY  DRM_IOW (DRM_COMMAND_BASE +
DRM_I915_GEM_VM_DESTROY, struct drm_i915_gem_vm_control)
+#define DRM_IOCTL_I915_GEM_VM_BIND     DRM_IOWR(DRM_COMMAND_BASE +
DRM_I915_GEM_VM_BIND, struct drm_i915_gem_vm_bind)
+#define DRM_IOCTL_I915_GEM_VM_UNBIND   DRM_IOWR(DRM_COMMAND_BASE +
DRM_I915_GEM_VM_UNBIND, struct drm_i915_gem_vm_unbind)

 /* Allow drivers to submit batchbuffers directly to hardware,
relying
  * on the security mechanisms provided by hardware.
@@ -749,6 +753,25 @@ typedef struct drm_i915_irq_wait {
 /* Query if the kernel supports the I915_USERPTR_PROBE flag. */
 #define I915_PARAM_HAS_USERPTR_PROBE 56

+/*
+ * VM_BIND feature version supported.
+ *
+ * The following versions of VM_BIND have been defined:
+ *
+ * 0: No VM_BIND support.
+ *
+ * 1: In VM_UNBIND calls, the UMD must specify the exact mappings
created
+ *    previously with VM_BIND, the ioctl will not support unbinding
multiple
+ *    mappings or splitting them. Similarly, VM_BIND calls will not
replace
+ *    any existing mappings.
+ *
+ * 2: The restrictions on unbinding partial or multiple mappings is
+ *    lifted, Similarly, binding will replace any mappings in the
given range.
+ *
+ * See struct drm_i915_gem_vm_bind and struct
drm_i915_gem_vm_unbind.
+ */
+#define I915_PARAM_VM_BIND_VERSION     57

Perhaps clarify that new versions are always backwards compatible?


I thought that is implicit by version 2 definition, but yah making it
explicit will be better.

Niranjana

+
 /* Must be kept compact -- no holes and well documented */

 typedef struct drm_i915_getparam {
@@ -1441,6 +1464,41 @@ struct drm_i915_gem_execbuffer2 {
 #define i915_execbuffer2_get_context_id(eb2) \
        ((eb2).rsvd1 & I915_EXEC_CONTEXT_ID_MASK)

+/**
+ * struct drm_i915_gem_timeline_fence - An input or output timeline
fence.
+ *
+ * The operation will wait for input fence to signal.
+ *
+ * The returned output fence will be signaled after the completion
of the
+ * operation.
+ */
+struct drm_i915_gem_timeline_fence {
+       /** @handle: User's handle for a drm_syncobj to wait on or
signal. */
+       __u32 handle;
+
+       /**
+        * @flags: Supported flags are:
+        *
+        * I915_TIMELINE_FENCE_WAIT:
+        * Wait for the input fence before the operation.
+        *
+        * I915_TIMELINE_FENCE_SIGNAL:
+        * Return operation completion fence as output.
+        */
+       __u32 flags;
+#define I915_TIMELINE_FENCE_WAIT            (1 << 0)
+#define I915_TIMELINE_FENCE_SIGNAL          (1 << 1)
+#define __I915_TIMELINE_FENCE_UNKNOWN_FLAGS (-
(I915_TIMELINE_FENCE_SIGNAL << 1))
+
+       /**
+        * @value: A point in the timeline.
+        * Value must be 0 for a binary drm_syncobj. A Value of 0 for
a
+        * timeline drm_syncobj is invalid as it turns a drm_syncobj
into a
+        * binary one.
+        */
+       __u64 value;
+};
+
 struct drm_i915_gem_pin {
        /** Handle of the buffer to be pinned. */
        __u32 handle;
@@ -2397,8 +2455,6 @@ struct drm_i915_gem_context_destroy {
  * The id of new VM (bound to the fd) for use with
I915_CONTEXT_PARAM_VM is
  * returned in the outparam @id.
  *
- * No flags are defined, with all bits reserved and must be zero.
- *
  * An extension chain maybe provided, starting with @extensions, and
terminated
  * by the @next_extension being 0. Currently, no extensions are
defined.
  *
@@ -2410,6 +2466,10 @@ struct drm_i915_gem_context_destroy {
  */
 struct drm_i915_gem_vm_control {
        __u64 extensions;
+
+#define I915_VM_CREATE_FLAGS_USE_VM_BIND       (1u << 0)
+#define I915_VM_CREATE_FLAGS_UNKNOWN \
+       (-(I915_VM_CREATE_FLAGS_USE_VM_BIND << 1))
        __u32 flags;
        __u32 vm_id;
 };
@@ -3602,6 +3662,134 @@ struct
drm_i915_gem_create_ext_protected_content {
 /* ID of the protected content session managed by i915 when PXP is
active */
 #define I915_PROTECTED_CONTENT_DEFAULT_SESSION 0xf

+/**
+ * struct drm_i915_gem_vm_bind - VA to object mapping to bind.
+ *
+ * This structure is passed to VM_BIND ioctl and specifies the
mapping of GPU
+ * virtual address (VA) range to the section of an object that
should be bound
+ * in the device page table of the specified address space (VM).
+ * The VA range specified must be unique (ie., not currently bound)
and can
+ * be mapped to whole object or a section of the object (partial
binding).
+ * Multiple VA mappings can be created to the same section of the
object
+ * (aliasing).
+ *
+ * The @start, @offset and @length must be 4K page aligned. However
the DG2
+ * and XEHPSDV has 64K page size for device local memory and has
compact page
+ * table. On those platforms, for binding device local-memory
objects, the
+ * @start, @offset and @length must be 64K aligned. Also, UMDs
should not mix
+ * the local memory 64K page and the system memory 4K page bindings
in the same
+ * 2M range.
+ *
+ * Error code -EINVAL will be returned if @start, @offset and
@length are not
+ * properly aligned. In version 1 (See I915_PARAM_VM_BIND_VERSION),
error code
+ * -ENOSPC will be returned if the VA range specified can't be
reserved.
+ *
+ * VM_BIND/UNBIND ioctl calls executed on different CPU threads
concurrently
+ * are not ordered. Furthermore, parts of the VM_BIND operation can
be done
+ * asynchronously, if valid @fence is specified.
+ */
+struct drm_i915_gem_vm_bind {
+       /** @vm_id: VM (address space) id to bind */
+       __u32 vm_id;
+
+       /** @handle: Object handle */
+       __u32 handle;
+
+       /** @start: Virtual Address start to bind */
+       __u64 start;
+
+       /** @offset: Offset in object to bind */
+       __u64 offset;
+
+       /** @length: Length of mapping to bind */
+       __u64 length;
+
+       /**
+        * @flags: Currently reserved, MBZ.
+        *
+        * Note that @fence carries its own flags.
+        */
+       __u64 flags;
+
+       /**
+        * @fence: Timeline fence for bind completion signaling.
+        *
+        * Timeline fence is of format struct
drm_i915_gem_timeline_fence.
+        *
+        * It is an out fence, hence using I915_TIMELINE_FENCE_WAIT
flag
+        * is invalid, and an error will be returned.
+        *
+        * If I915_TIMELINE_FENCE_SIGNAL flag is not set, then out
fence
+        * is not requested and binding is completed synchronously.
+        */
+       struct drm_i915_gem_timeline_fence fence;
+
+       /**
+        * @extensions: Zero-terminated chain of extensions.
+        *
+        * For future extensions. See struct i915_user_extension.
+        */
+       __u64 extensions;
+};
+
+/**
+ * struct drm_i915_gem_vm_unbind - VA to object mapping to unbind.
+ *
+ * This structure is passed to VM_UNBIND ioctl and specifies the GPU
virtual
+ * address (VA) range that should be unbound from the device page
table of the
+ * specified address space (VM). VM_UNBIND will force unbind the
specified
+ * range from device page table without waiting for any GPU job to
complete.
+ * It is UMDs responsibility to ensure the mapping is no longer in
use before
+ * calling VM_UNBIND.
+ *
+ * If the specified mapping is not found, the ioctl will simply
return without
+ * any error.
+ *
+ * VM_BIND/UNBIND ioctl calls executed on different CPU threads
concurrently
+ * are not ordered. Furthermore, parts of the VM_UNBIND operation
can be done
+ * asynchronously, if valid @fence is specified.
+ */
+struct drm_i915_gem_vm_unbind {
+       /** @vm_id: VM (address space) id to bind */
+       __u32 vm_id;
+
+       /** @rsvd: Reserved, MBZ */
+       __u32 rsvd;
+
+       /** @start: Virtual Address start to unbind */
+       __u64 start;
+
+       /** @length: Length of mapping to unbind */
+       __u64 length;
+
+       /**
+        * @flags: Currently reserved, MBZ.
+        *
+        * Note that @fence carries its own flags.
+        */
+       __u64 flags;
+
+       /**
+        * @fence: Timeline fence for unbind completion signaling.
+        *
+        * Timeline fence is of format struct
drm_i915_gem_timeline_fence.
+        *
+        * It is an out fence, hence using I915_TIMELINE_FENCE_WAIT
flag
+        * is invalid, and an error will be returned.
+        *
+        * If I915_TIMELINE_FENCE_SIGNAL flag is not set, then out
fence
+        * is not requested and unbinding is completed synchronously.
+        */
+       struct drm_i915_gem_timeline_fence fence;
+
+       /**
+        * @extensions: Zero-terminated chain of extensions.
+        *
+        * For future extensions. See struct i915_user_extension.
+        */
+       __u64 extensions;
+};
+
 #if defined(__cplusplus)
 }
 #endif




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