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.
Regards, Tvrtko
Regards, Tvrtkoreturn -ENODEV; rcu_read_lock(); diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.h b/drivers/gpu/drm/i915/gem/i915_gem_context.h index da6e8b506d96..37536a260e6e 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_context.h +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.h @@ -154,6 +154,13 @@ i915_gem_context_vm(struct i915_gem_context *ctx) return rcu_dereference_protected(ctx->vm, lockdep_is_held(&ctx->mutex)); } +static inline bool i915_gem_context_is_full_ppgtt(struct i915_gem_context *ctx) +{ + GEM_BUG_ON(!!rcu_access_pointer(ctx->vm) != HAS_FULL_PPGTT(ctx->i915)); + + return !!rcu_access_pointer(ctx->vm); +} + static inline struct i915_address_space * i915_gem_context_get_eb_vm(struct i915_gem_context *ctx) { diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c index 905b1cbd22d5..40f08948f0b2 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c @@ -749,7 +749,7 @@ static int eb_select_context(struct i915_execbuffer *eb) return PTR_ERR(ctx); eb->gem_context = ctx; - if (rcu_access_pointer(ctx->vm)) + if (i915_gem_context_is_full_ppgtt(ctx)) eb->invalid_flags |= EXEC_OBJECT_NEEDS_GTT; return 0; diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c index fc7fb33a3a52..947154e445a7 100644 --- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c +++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c @@ -704,7 +704,7 @@ static int igt_ctx_exec(void *arg) pr_err("Failed to fill dword %lu [%lu/%lu] with gpu (%s) [full-ppgtt? %s], err=%d\n", ndwords, dw, max_dwords(obj), engine->name, - yesno(!!rcu_access_pointer(ctx->vm)), + yesno(i915_gem_context_is_full_ppgtt(ctx)), err); intel_context_put(ce); kernel_context_close(ctx); @@ -838,7 +838,7 @@ static int igt_shared_ctx_exec(void *arg) pr_err("Failed to fill dword %lu [%lu/%lu] with gpu (%s) [full-ppgtt? %s], err=%d\n", ndwords, dw, max_dwords(obj), engine->name, - yesno(!!rcu_access_pointer(ctx->vm)), + yesno(i915_gem_context_is_full_ppgtt(ctx)), err); intel_context_put(ce); kernel_context_close(ctx); @@ -1417,7 +1417,7 @@ static int igt_ctx_readonly(void *arg) pr_err("Failed to fill dword %lu [%lu/%lu] with gpu (%s) [full-ppgtt? %s], err=%d\n", ndwords, dw, max_dwords(obj), ce->engine->name, - yesno(!!ctx_vm(ctx)), + yesno(i915_gem_context_is_full_ppgtt(ctx)), err); i915_gem_context_unlock_engines(ctx); goto out_file;
