[PATCH v4 2/9] drm/xe: Add "null_sparse" type to VM snap properties

[Matthew Brost]

On Wed, May 07, 2025 at 02:36:28PM -0600, Cavitt, Jonathan wrote:
> -----Original Message-----
> From: Intel-xe <intel-xe-bounces at lists.freedesktop.org> On Behalf Of Matthew Brost
> Sent: Wednesday, May 7, 2025 1:16 PM
> To: intel-xe at lists.freedesktop.org
> Cc: Souza, Jose <jose.souza at intel.com>; Santa, Carlos <carlos.santa at intel.com>; Venkatesh Reddy, Sushma <sushma.venkatesh.reddy at intel.com>
> Subject: [PATCH v4 2/9] drm/xe: Add "null_sparse" type to VM snap properties
> > 
> > Add "null_sparse" type to VM snap properties indicating the VMA reads
> > zero and writes are droppped. This is useful information for debug and
> > will help build a robust GPU hang replay tool.
> > 
> > The current format is:
> > 
> > [<vma address>]: <permissions>|<type>
> > 
> > Permissions has two options, either "read_only" or "read_write".
> > 
> > Type has three options, either "userptr", "null_sparse", or "bo".
> > 
> > Cc: José Roberto de Souza <jose.souza at intel.com>
> > Signed-off-by: Matthew Brost <matthew.brost at intel.com>
> 
> Admittedly, this looks like it could or should be squashed with
> the previous patch in this series, but it's not a blocking request.
> 

Yea this one should probably be squashed. Will do.

Matt

> Reviewed-by: Jonathan Cavitt <jonathan.cavitt at intel.com>
> -Jonathan Cavitt
> 
> > ---
> >  drivers/gpu/drm/xe/xe_vm.c | 11 ++++++++++-
> >  1 file changed, 10 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
> > index ddeec681f71f..95c51834c620 100644
> > --- a/drivers/gpu/drm/xe/xe_vm.c
> > +++ b/drivers/gpu/drm/xe/xe_vm.c
> > @@ -3729,6 +3729,7 @@ struct xe_vm_snapshot {
> >  		unsigned long len;
> >  #define XE_VM_SNAP_FLAG_USERPTR		BIT(0)
> >  #define XE_VM_SNAP_FLAG_READ_ONLY	BIT(1)
> > +#define XE_VM_SNAP_FLAG_IS_NULL		BIT(2)
> >  		unsigned long flags;
> >  		struct xe_bo *bo;
> >  		void *data;
> > @@ -3786,6 +3787,8 @@ struct xe_vm_snapshot *xe_vm_snapshot_capture(struct xe_vm *vm)
> >  
> >  			snap->snap[i].bo_ofs = xe_vma_userptr(vma);
> >  			snap->snap[i].flags |= XE_VM_SNAP_FLAG_USERPTR;
> > +		} else if (xe_vma_is_null(vma)) {
> > +			snap->snap[i].flags |= XE_VM_SNAP_FLAG_IS_NULL;
> >  		} else {
> >  			snap->snap[i].data = ERR_PTR(-ENOENT);
> >  		}
> > @@ -3806,7 +3809,8 @@ void xe_vm_snapshot_capture_delayed(struct xe_vm_snapshot *snap)
> >  		struct xe_bo *bo = snap->snap[i].bo;
> >  		int err;
> >  
> > -		if (IS_ERR(snap->snap[i].data))
> > +		if (IS_ERR(snap->snap[i].data) ||
> > +		    snap->snap[i].flags & XE_VM_SNAP_FLAG_IS_NULL)
> >  			continue;
> >  
> >  		snap->snap[i].data = kvmalloc(snap->snap[i].len, GFP_USER);
> > @@ -3858,6 +3862,8 @@ void xe_vm_snapshot_print(struct xe_vm_snapshot *snap, struct drm_printer *p)
> >  		drm_printf(p, "[%llx].properties: %s|%s\n", snap->snap[i].ofs,
> >  			   snap->snap[i].flags & XE_VM_SNAP_FLAG_READ_ONLY ?
> >  			   "read_only" : "read_write",
> > +			   snap->snap[i].flags & XE_VM_SNAP_FLAG_IS_NULL ?
> > +			   "null_sparse" :
> >  			   snap->snap[i].flags & XE_VM_SNAP_FLAG_USERPTR ?
> >  			   "userptr" : "bo");
> >  
> > @@ -3867,6 +3873,9 @@ void xe_vm_snapshot_print(struct xe_vm_snapshot *snap, struct drm_printer *p)
> >  			continue;
> >  		}
> >  
> > +		if (snap->snap[i].flags & XE_VM_SNAP_FLAG_IS_NULL)
> > +			continue;
> > +
> >  		drm_printf(p, "[%llx].data: ", snap->snap[i].ofs);
> >  
> >  		for (j = 0; j < snap->snap[i].len; j += sizeof(u32)) {
> > -- 
> > 2.34.1
> > 
> >