[Intel-gfx] [PATCH 11/19] drm/i915: Update the helper to set correct mapping
Matthew Auld
matthew.auld at intel.com
Wed Apr 21 11:42:23 UTC 2021
On 19/04/2021 16:01, Tvrtko Ursulin wrote:
>
> On 19/04/2021 15:37, Matthew Auld wrote:
>> On 19/04/2021 15:07, Tvrtko Ursulin wrote:
>>>
>>> On 19/04/2021 12:30, Matthew Auld wrote:
>>>> On 15/04/2021 12:05, Tvrtko Ursulin wrote:
>>>>>
>>>>> On 15/04/2021 10:23, Matthew Auld wrote:
>>>>>> On Thu, 15 Apr 2021 at 09:21, Tvrtko Ursulin
>>>>>> <tvrtko.ursulin at linux.intel.com> wrote:
>>>>>>>
>>>>>>>
>>>>>>> On 14/04/2021 17:20, Matthew Auld wrote:
>>>>>>>> On Wed, 14 Apr 2021 at 16:22, Tvrtko Ursulin
>>>>>>>> <tvrtko.ursulin at linux.intel.com> wrote:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On 12/04/2021 10:05, Matthew Auld wrote:
>>>>>>>>>> From: Venkata Sandeep Dhanalakota
>>>>>>>>>> <venkata.s.dhanalakota at intel.com>
>>>>>>>>>>
>>>>>>>>>> Determine the possible coherent map type based on object
>>>>>>>>>> location,
>>>>>>>>>> and if target has llc or if user requires an always coherent
>>>>>>>>>> mapping.
>>>>>>>>>>
>>>>>>>>>> Cc: Matthew Auld <matthew.auld at intel.com>
>>>>>>>>>> Cc: CQ Tang <cq.tang at intel.com>
>>>>>>>>>> Suggested-by: Michal Wajdeczko <michal.wajdeczko at intel.com>
>>>>>>>>>> Signed-off-by: Venkata Sandeep Dhanalakota
>>>>>>>>>> <venkata.s.dhanalakota at intel.com>
>>>>>>>>>> ---
>>>>>>>>>> drivers/gpu/drm/i915/gt/intel_engine_cs.c | 3 ++-
>>>>>>>>>> drivers/gpu/drm/i915/gt/intel_engine_pm.c | 2 +-
>>>>>>>>>> drivers/gpu/drm/i915/gt/intel_lrc.c | 4 +++-
>>>>>>>>>> drivers/gpu/drm/i915/gt/intel_ring.c | 9 ++++++---
>>>>>>>>>> drivers/gpu/drm/i915/gt/selftest_context.c | 3 ++-
>>>>>>>>>> drivers/gpu/drm/i915/gt/selftest_hangcheck.c | 4 ++--
>>>>>>>>>> drivers/gpu/drm/i915/gt/selftest_lrc.c | 4 +++-
>>>>>>>>>> drivers/gpu/drm/i915/gt/uc/intel_guc.c | 4 +++-
>>>>>>>>>> drivers/gpu/drm/i915/gt/uc/intel_huc.c | 4 +++-
>>>>>>>>>> drivers/gpu/drm/i915/i915_drv.h | 11 +++++++++--
>>>>>>>>>> drivers/gpu/drm/i915/selftests/igt_spinner.c | 4 ++--
>>>>>>>>>> 11 files changed, 36 insertions(+), 16 deletions(-)
>>>>>>>>>>
>>>>>>>>>> diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c
>>>>>>>>>> b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
>>>>>>>>>> index efe935f80c1a..b79568d370f5 100644
>>>>>>>>>> --- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c
>>>>>>>>>> +++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
>>>>>>>>>> @@ -664,7 +664,8 @@ static int init_status_page(struct
>>>>>>>>>> intel_engine_cs *engine)
>>>>>>>>>> if (ret)
>>>>>>>>>> goto err;
>>>>>>>>>>
>>>>>>>>>> - vaddr = i915_gem_object_pin_map(obj, I915_MAP_WB);
>>>>>>>>>> + vaddr = i915_gem_object_pin_map(obj,
>>>>>>>>>> + i915_coherent_map_type(engine->i915, obj, true));
>>>>>>>>>> if (IS_ERR(vaddr)) {
>>>>>>>>>> ret = PTR_ERR(vaddr);
>>>>>>>>>> goto err_unpin;
>>>>>>>>>> diff --git a/drivers/gpu/drm/i915/gt/intel_engine_pm.c
>>>>>>>>>> b/drivers/gpu/drm/i915/gt/intel_engine_pm.c
>>>>>>>>>> index 7c9af86fdb1e..47f4397095e5 100644
>>>>>>>>>> --- a/drivers/gpu/drm/i915/gt/intel_engine_pm.c
>>>>>>>>>> +++ b/drivers/gpu/drm/i915/gt/intel_engine_pm.c
>>>>>>>>>> @@ -23,7 +23,7 @@ static void dbg_poison_ce(struct
>>>>>>>>>> intel_context *ce)
>>>>>>>>>>
>>>>>>>>>> if (ce->state) {
>>>>>>>>>> struct drm_i915_gem_object *obj = ce->state->obj;
>>>>>>>>>> - int type =
>>>>>>>>>> i915_coherent_map_type(ce->engine->i915);
>>>>>>>>>> + int type =
>>>>>>>>>> i915_coherent_map_type(ce->engine->i915, obj, true);
>>>>>>>>>> void *map;
>>>>>>>>>>
>>>>>>>>>> if (!i915_gem_object_trylock(obj))
>>>>>>>>>> diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c
>>>>>>>>>> b/drivers/gpu/drm/i915/gt/intel_lrc.c
>>>>>>>>>> index e86897cde984..aafe2a4df496 100644
>>>>>>>>>> --- a/drivers/gpu/drm/i915/gt/intel_lrc.c
>>>>>>>>>> +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
>>>>>>>>>> @@ -903,7 +903,9 @@ lrc_pre_pin(struct intel_context *ce,
>>>>>>>>>> GEM_BUG_ON(!i915_vma_is_pinned(ce->state));
>>>>>>>>>>
>>>>>>>>>> *vaddr = i915_gem_object_pin_map(ce->state->obj,
>>>>>>>>>> - i915_coherent_map_type(ce->engine->i915) |
>>>>>>>>>> + i915_coherent_map_type(ce->engine->i915,
>>>>>>>>>> + ce->state->obj,
>>>>>>>>>> + false) |
>>>>>>>>>> I915_MAP_OVERRIDE);
>>>>>>>>>>
>>>>>>>>>> return PTR_ERR_OR_ZERO(*vaddr);
>>>>>>>>>> diff --git a/drivers/gpu/drm/i915/gt/intel_ring.c
>>>>>>>>>> b/drivers/gpu/drm/i915/gt/intel_ring.c
>>>>>>>>>> index aee0a77c77e0..3cf6c7e68108 100644
>>>>>>>>>> --- a/drivers/gpu/drm/i915/gt/intel_ring.c
>>>>>>>>>> +++ b/drivers/gpu/drm/i915/gt/intel_ring.c
>>>>>>>>>> @@ -53,9 +53,12 @@ int intel_ring_pin(struct intel_ring *ring,
>>>>>>>>>> struct i915_gem_ww_ctx *ww)
>>>>>>>>>>
>>>>>>>>>> if (i915_vma_is_map_and_fenceable(vma))
>>>>>>>>>> addr = (void __force *)i915_vma_pin_iomap(vma);
>>>>>>>>>> - else
>>>>>>>>>> - addr = i915_gem_object_pin_map(vma->obj,
>>>>>>>>>> - i915_coherent_map_type(vma->vm->i915));
>>>>>>>>>> + else {
>>>>>>>>>> + int type = i915_coherent_map_type(vma->vm->i915,
>>>>>>>>>> vma->obj, false);
>>>>>>>>>> +
>>>>>>>>>> + addr = i915_gem_object_pin_map(vma->obj, type);
>>>>>>>>>> + }
>>>>>>>>>> +
>>>>>>>>>> if (IS_ERR(addr)) {
>>>>>>>>>> ret = PTR_ERR(addr);
>>>>>>>>>> goto err_ring;
>>>>>>>>>> diff --git a/drivers/gpu/drm/i915/gt/selftest_context.c
>>>>>>>>>> b/drivers/gpu/drm/i915/gt/selftest_context.c
>>>>>>>>>> index b9bdd1d23243..26685b927169 100644
>>>>>>>>>> --- a/drivers/gpu/drm/i915/gt/selftest_context.c
>>>>>>>>>> +++ b/drivers/gpu/drm/i915/gt/selftest_context.c
>>>>>>>>>> @@ -88,7 +88,8 @@ static int __live_context_size(struct
>>>>>>>>>> intel_engine_cs *engine)
>>>>>>>>>> goto err;
>>>>>>>>>>
>>>>>>>>>> vaddr = i915_gem_object_pin_map_unlocked(ce->state->obj,
>>>>>>>>>> - i915_coherent_map_type(engine->i915));
>>>>>>>>>> + i915_coherent_map_type(engine->i915,
>>>>>>>>>> + ce->state->obj, false));
>>>>>>>>>> if (IS_ERR(vaddr)) {
>>>>>>>>>> err = PTR_ERR(vaddr);
>>>>>>>>>> intel_context_unpin(ce);
>>>>>>>>>> diff --git a/drivers/gpu/drm/i915/gt/selftest_hangcheck.c
>>>>>>>>>> b/drivers/gpu/drm/i915/gt/selftest_hangcheck.c
>>>>>>>>>> index 746985971c3a..5b63d4df8c93 100644
>>>>>>>>>> --- a/drivers/gpu/drm/i915/gt/selftest_hangcheck.c
>>>>>>>>>> +++ b/drivers/gpu/drm/i915/gt/selftest_hangcheck.c
>>>>>>>>>> @@ -69,7 +69,7 @@ static int hang_init(struct hang *h, struct
>>>>>>>>>> intel_gt *gt)
>>>>>>>>>> h->seqno = memset(vaddr, 0xff, PAGE_SIZE);
>>>>>>>>>>
>>>>>>>>>> vaddr = i915_gem_object_pin_map_unlocked(h->obj,
>>>>>>>>>> - i915_coherent_map_type(gt->i915));
>>>>>>>>>> + i915_coherent_map_type(gt->i915, h->obj, false));
>>>>>>>>>> if (IS_ERR(vaddr)) {
>>>>>>>>>> err = PTR_ERR(vaddr);
>>>>>>>>>> goto err_unpin_hws;
>>>>>>>>>> @@ -130,7 +130,7 @@ hang_create_request(struct hang *h, struct
>>>>>>>>>> intel_engine_cs *engine)
>>>>>>>>>> return ERR_CAST(obj);
>>>>>>>>>> }
>>>>>>>>>>
>>>>>>>>>> - vaddr = i915_gem_object_pin_map_unlocked(obj,
>>>>>>>>>> i915_coherent_map_type(gt->i915));
>>>>>>>>>> + vaddr = i915_gem_object_pin_map_unlocked(obj,
>>>>>>>>>> i915_coherent_map_type(gt->i915, obj, false));
>>>>>>>>>> if (IS_ERR(vaddr)) {
>>>>>>>>>> i915_gem_object_put(obj);
>>>>>>>>>> i915_vm_put(vm);
>>>>>>>>>> diff --git a/drivers/gpu/drm/i915/gt/selftest_lrc.c
>>>>>>>>>> b/drivers/gpu/drm/i915/gt/selftest_lrc.c
>>>>>>>>>> index 85e7df6a5123..d8f6623524e8 100644
>>>>>>>>>> --- a/drivers/gpu/drm/i915/gt/selftest_lrc.c
>>>>>>>>>> +++ b/drivers/gpu/drm/i915/gt/selftest_lrc.c
>>>>>>>>>> @@ -1221,7 +1221,9 @@ static int compare_isolation(struct
>>>>>>>>>> intel_engine_cs *engine,
>>>>>>>>>> }
>>>>>>>>>>
>>>>>>>>>> lrc = i915_gem_object_pin_map_unlocked(ce->state->obj,
>>>>>>>>>> - i915_coherent_map_type(engine->i915));
>>>>>>>>>> + i915_coherent_map_type(engine->i915,
>>>>>>>>>> + ce->state->obj,
>>>>>>>>>> + false));
>>>>>>>>>> if (IS_ERR(lrc)) {
>>>>>>>>>> err = PTR_ERR(lrc);
>>>>>>>>>> goto err_B1;
>>>>>>>>>> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.c
>>>>>>>>>> b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
>>>>>>>>>> index 78305b2ec89d..adae04c47aab 100644
>>>>>>>>>> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.c
>>>>>>>>>> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
>>>>>>>>>> @@ -682,7 +682,9 @@ int intel_guc_allocate_and_map_vma(struct
>>>>>>>>>> intel_guc *guc, u32 size,
>>>>>>>>>> if (IS_ERR(vma))
>>>>>>>>>> return PTR_ERR(vma);
>>>>>>>>>>
>>>>>>>>>> - vaddr = i915_gem_object_pin_map_unlocked(vma->obj,
>>>>>>>>>> I915_MAP_WB);
>>>>>>>>>> + vaddr = i915_gem_object_pin_map_unlocked(vma->obj,
>>>>>>>>>> + i915_coherent_map_type(guc_to_gt(guc)->i915,
>>>>>>>>>> + vma->obj, true));
>>>>>>>>>> if (IS_ERR(vaddr)) {
>>>>>>>>>> i915_vma_unpin_and_release(&vma, 0);
>>>>>>>>>> return PTR_ERR(vaddr);
>>>>>>>>>> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_huc.c
>>>>>>>>>> b/drivers/gpu/drm/i915/gt/uc/intel_huc.c
>>>>>>>>>> index 2126dd81ac38..56d2144dc6a0 100644
>>>>>>>>>> --- a/drivers/gpu/drm/i915/gt/uc/intel_huc.c
>>>>>>>>>> +++ b/drivers/gpu/drm/i915/gt/uc/intel_huc.c
>>>>>>>>>> @@ -82,7 +82,9 @@ static int intel_huc_rsa_data_create(struct
>>>>>>>>>> intel_huc *huc)
>>>>>>>>>> if (IS_ERR(vma))
>>>>>>>>>> return PTR_ERR(vma);
>>>>>>>>>>
>>>>>>>>>> - vaddr = i915_gem_object_pin_map_unlocked(vma->obj,
>>>>>>>>>> I915_MAP_WB);
>>>>>>>>>> + vaddr = i915_gem_object_pin_map_unlocked(vma->obj,
>>>>>>>>>> + i915_coherent_map_type(gt->i915,
>>>>>>>>>> + vma->obj, true));
>>>>>>>>>> if (IS_ERR(vaddr)) {
>>>>>>>>>> i915_vma_unpin_and_release(&vma, 0);
>>>>>>>>>> return PTR_ERR(vaddr);
>>>>>>>>>> diff --git a/drivers/gpu/drm/i915/i915_drv.h
>>>>>>>>>> b/drivers/gpu/drm/i915/i915_drv.h
>>>>>>>>>> index 69e43bf91a15..2abbc06712a4 100644
>>>>>>>>>> --- a/drivers/gpu/drm/i915/i915_drv.h
>>>>>>>>>> +++ b/drivers/gpu/drm/i915/i915_drv.h
>>>>>>>>>> @@ -78,6 +78,7 @@
>>>>>>>>>> #include "gem/i915_gem_context_types.h"
>>>>>>>>>> #include "gem/i915_gem_shrinker.h"
>>>>>>>>>> #include "gem/i915_gem_stolen.h"
>>>>>>>>>> +#include "gem/i915_gem_lmem.h"
>>>>>>>>>>
>>>>>>>>>> #include "gt/intel_engine.h"
>>>>>>>>>> #include "gt/intel_gt_types.h"
>>>>>>>>>> @@ -1921,9 +1922,15 @@ static inline int
>>>>>>>>>> intel_hws_csb_write_index(struct drm_i915_private *i915)
>>>>>>>>>> }
>>>>>>>>>>
>>>>>>>>>> static inline enum i915_map_type
>>>>>>>>>> -i915_coherent_map_type(struct drm_i915_private *i915)
>>>>>>>>>> +i915_coherent_map_type(struct drm_i915_private *i915,
>>>>>>>>>> + struct drm_i915_gem_object *obj, bool
>>>>>>>>>> always_coherent)
>>>>>>>>>> {
>>>>>>>>>> - return HAS_LLC(i915) ? I915_MAP_WB : I915_MAP_WC;
>>>>>>>>>> + if (i915_gem_object_is_lmem(obj))
>>>>>>>>>> + return I915_MAP_WC;
>>>>>>>>>> + if (HAS_LLC(i915) || always_coherent)
>>>>>>>>>> + return I915_MAP_WB;
>>>>>>>>>> + else
>>>>>>>>>> + return I915_MAP_WC;
>>>>>>>>>
>>>>>>>>> Seems this patch is doing two things.
>>>>>>>>>
>>>>>>>>> First it is adding lmem support to this helper by always
>>>>>>>>> returning WC
>>>>>>>>> for lmem objects.
>>>>>>>>>
>>>>>>>>> Secondly it is introducing an idea of "always coherent" in a
>>>>>>>>> helper
>>>>>>>>> called i915_coherent_map_type. Could someone explain what is
>>>>>>>>> coherent vs
>>>>>>>>> always coherent?
>>>>>>>>>
>>>>>>>>> And also, why is always coherent happy with WB? Sounds counter
>>>>>>>>> intuitive
>>>>>>>>> to me.
>>>>>>>>
>>>>>>>> All this does is try to keep the existing behaviour intact, whilst
>>>>>>>> also ensuring that all lmem objects are mapped using only WC, no
>>>>>>>> matter what. The always_coherent=true thing is for the existing
>>>>>>>> places
>>>>>>>> where we sometimes map the object using WB, without first
>>>>>>>> considering
>>>>>>>> whether the device has the fast shared LLC vs snooping. Yes, it's
>>>>>>>> slightly ugly :)
>>>>>>>
>>>>>>> Not fully following - if we had to write kerneldoc for
>>>>>>> always_coherent
>>>>>>> input argument - what it would say?
>>>>>>
>>>>>> @always_coherent - If true we should always try to map the object
>>>>>> using WB. If false we should only map as WB if the device supports
>>>>>> the
>>>>>> fast shared LLC, in the case of snooped devices we will map use WC.
>>>>>> Note that If the resource is lmem then we will always map as WC,
>>>>>> regardless of the value of always_coherent, since that's all we
>>>>>> currently support.
>>>>>>
>>>>>> Maybe the naming is poor?
>>>>>
>>>>> Maybe just confusing to me, not sure yet.
>>>>>
>>>>> So always_coherent is not about how the callers wants to use it,
>>>>> but about platform knowledge? Or a performance concern for LLC vs
>>>>> snooping cases? Does WB works (coherently) on snooping platforms?
>>>>
>>>> The always_coherent=true is for the existing callers that want WB,
>>>> regardless of LLC vs snooping.
>>>>
>>>> The other callers use the existing i915_coherent_map_type() which
>>>> only gives out WB for LLC platforms.
>>>>
>>>> AFAIK, LLC vs snooping should offer the same in terms of coherency,
>>>> but in terms of performance the shared LLC is much faster, and so
>>>> for snooping platforms we choose to not enable WB everywhere.
>>>>
>>>> On top of that we now have lmem, but for that we only allow WC. This
>>>> patch just rolls all of that into one helper, while keeping the
>>>> existing behaviour unchanged.
>>>
>>> Thanks. But I am still struggling with the API. :(
>>>
>>> Is the introduction of always_coherent flag in the context of DG1
>>> required even? AFAICT for lmem objects the flag is ignored so no?
>>
>> If we drop the flag/helper thing, then we need something like:
>>
>> type = WB;
>> if (i915_gem_object_is_lmem(obj))
>> type = WC;
>>
>> vaddr = i915_gem_object_pin_map(obj, type);
>>
>> In all the places where we currently do:
>>
>> vaddr = i915_gem_object_pin_map(obj, WB);
>>
>> Where obj can be lmem, so ctx, ring, guc etc. Is that better or worse?
>> The existing i915_coherent_map_type() callers should work as-is, since
>> DG1 is snooped. And this patch just extends that to cover all cases.
>>
>> Perhaps we need a new helper instead? Maybe you have a better idea?
>
> Not yet. Would it make sense to put something in kerneldoc about when
> callers might choose always_coherent true vs false? In terms of expected
> usage (frequency, simplicity?) and any rules with regards when callers
> need to worry about flushing/ordering when there are mixed read and writes?
Hmmm, looking at this again, maybe for now we should just go with:
type = WB;
if (i915_gem_object_is_lmem(obj))
type = WC;
vaddr = i915_gem_object_pin_map(obj, type)
Which is way less confusing, plus there are only a handful of places
where we need this, so doesn't seem too bad?
Alternatively, we could wrap that in something like:
/* Returns WB for system memory, or WC for local memory */
void *i915_gem_object_pin_map_default(obj);
Thoughts?
>
> Regards,
>
> Tvrtko
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