> -----Original Message----- > From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxxxxxxx> > Sent: Thursday, September 2, 2021 9:42 AM > To: Daniel Vetter <daniel@xxxxxxxx> > Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>; DRI Development <dri- > devel@xxxxxxxxxxxxxxxxxxxxx>; Intel Graphics Development <intel- > gfx@xxxxxxxxxxxxxxxxxxxxx>; Maarten Lankhorst > <maarten.lankhorst@xxxxxxxxxxxxxxx>; Vetter, Daniel > <daniel.vetter@xxxxxxxxx>; Bloomfield, Jon <jon.bloomfield@xxxxxxxxx>; > Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>; Joonas Lahtinen > <joonas.lahtinen@xxxxxxxxxxxxxxx>; Thomas Hellström > <thomas.hellstrom@xxxxxxxxxxxxxxx>; Auld, Matthew > <matthew.auld@xxxxxxxxx>; Landwerlin, Lionel G > <lionel.g.landwerlin@xxxxxxxxx>; Dave Airlie <airlied@xxxxxxxxxx>; Jason > Ekstrand <jason@xxxxxxxxxxxxxx> > Subject: Re: [Intel-gfx] [PATCH 07/11] drm/i915: Add > i915_gem_context_is_full_ppgtt > > > On 02/09/2021 16:22, Daniel Vetter wrote: > > On Thu, Sep 02, 2021 at 03:54:36PM +0100, Tvrtko Ursulin wrote: > >> On 02/09/2021 15:20, Daniel Vetter wrote: > >>> And use it anywhere we have open-coded checks for ctx->vm that really > >>> only check for full ppgtt. > >>> > >>> Plus for paranoia add a GEM_BUG_ON that checks it's really only set > >>> when we have full ppgtt, just in case. gem_context->vm is different > >>> since it's NULL in ggtt mode, unlike intel_context->vm or gt->vm, > >>> which is always set. > >>> > >>> v2: 0day found a testcase that I missed. > >>> > >>> Reviewed-by: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx> > >>> Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx> > >>> Cc: Jon Bloomfield <jon.bloomfield@xxxxxxxxx> > >>> Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > >>> Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx> > >>> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx> > >>> Cc: Daniel Vetter <daniel.vetter@xxxxxxxx> > >>> Cc: "Thomas Hellström" <thomas.hellstrom@xxxxxxxxxxxxxxx> > >>> Cc: Matthew Auld <matthew.auld@xxxxxxxxx> > >>> Cc: Lionel Landwerlin <lionel.g.landwerlin@xxxxxxxxx> > >>> Cc: Dave Airlie <airlied@xxxxxxxxxx> > >>> Cc: Jason Ekstrand <jason@xxxxxxxxxxxxxx> > >>> --- > >>> drivers/gpu/drm/i915/gem/i915_gem_context.c | 2 +- > >>> drivers/gpu/drm/i915/gem/i915_gem_context.h | 7 +++++++ > >>> drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c | 2 +- > >>> drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c | 6 +++--- > >>> 4 files changed, 12 insertions(+), 5 deletions(-) > >>> > >>> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c > b/drivers/gpu/drm/i915/gem/i915_gem_context.c > >>> index 7a566fb7cca4..1eec85944c1f 100644 > >>> --- a/drivers/gpu/drm/i915/gem/i915_gem_context.c > >>> +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c > >>> @@ -1566,7 +1566,7 @@ static int get_ppgtt(struct > drm_i915_file_private *file_priv, > >>> int err; > >>> u32 id; > >>> - if (!rcu_access_pointer(ctx->vm)) > >>> + if (!i915_gem_context_is_full_ppgtt(ctx)) > >> > >> It reads a bit wrong because GEM context cannot *be* full ppggt. It can > be > >> associated with a VM which is or isn't full ppgtt. So a test on a VM > >> retrieved from a context is semnntically more correct. Perhaps you want > to > >> consider adding a helper to that effect instead? It could mean splitting > >> into two helpers (getter + test) or maybe just renaming would work. Like > >> i915_gem_context_has_full_ppgtt_vm(ctx)? > > > > The pointer isn't set when the driver/context isn't running in full ppgtt > > mode. This is why I've added the GEM_BUG_ON to check we're not > breaking > > any invariants. So yeah it is a full ppgtt context or it's not, that is > > indeed the question here. > > > > I'm happy to bikeshed the naming, but I don't see how your suggestion is > > an improvement. > > I think the pointer being set or not is implementation detail, for > instance we could have it always set just like it is in intel_context. > > I simply think GEM context *isn't* full ppgtt, but the VM is. And since > GEM context *points* to a VM, *has* is the right verb in my mind. You > did not write why do you not see has as more correct than is so I don't > want to be guessing too much. FWIW, I agree with Tvrtko. i915_gem_context_is_full_ppgtt is incorrect grammar. It IS a bike shed, but, hey it'll live for a while.
