* [PATCH 1/2] drm/i915/gt: Move TLB invalidation to its own file
2022-07-28 12:30 [PATCH 0/2] Move TLB invalidation code for its own file and document it Mauro Carvalho Chehab
@ 2022-07-28 12:30 ` Mauro Carvalho Chehab
2022-07-28 12:30 ` [PATCH 2/2] drm/i915/gt: document TLB cache invalidation functions Mauro Carvalho Chehab
1 sibling, 0 replies; 3+ messages in thread
From: Mauro Carvalho Chehab @ 2022-07-28 12:30 UTC (permalink / raw)
Cc: David Airlie, dri-devel, Daniele Ceraolo Spurio, Fei Yang,
Abdiel Janulgue, Chris Wilson, Matthew Auld, Andi Shyti,
Tomas Winkler, Thomas Hellström, Casey Bowman,
Lucas De Marchi, intel-gfx, Rodrigo Vivi, Mauro Carvalho Chehab,
Tvrtko Ursulin, linux-kernel
From: Chris Wilson <chris.p.wilson@intel.com>
Prepare for supporting more TLB invalidation scenarios by moving
the current MMIO invalidation to its own file.
Signed-off-by: Chris Wilson <chris.p.wilson@intel.com>
Cc: Fei Yang <fei.yang@intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
---
To avoid mailbombing on a large number of people, only mailing lists were C/C on the cover.
See [PATCH 0/2] at: https://lore.kernel.org/all/cover.1659011328.git.mchehab@kernel.org/
drivers/gpu/drm/i915/Makefile | 1 +
drivers/gpu/drm/i915/gem/i915_gem_pages.c | 4 +-
drivers/gpu/drm/i915/gt/intel_gt.c | 168 +-------------------
drivers/gpu/drm/i915/gt/intel_gt.h | 12 --
drivers/gpu/drm/i915/gt/intel_tlb.c | 183 ++++++++++++++++++++++
drivers/gpu/drm/i915/gt/intel_tlb.h | 29 ++++
drivers/gpu/drm/i915/i915_vma.c | 1 +
7 files changed, 219 insertions(+), 179 deletions(-)
create mode 100644 drivers/gpu/drm/i915/gt/intel_tlb.c
create mode 100644 drivers/gpu/drm/i915/gt/intel_tlb.h
diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index 522ef9b4aff3..d3df9832d1f7 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -126,6 +126,7 @@ gt-y += \
gt/intel_sseu.o \
gt/intel_sseu_debugfs.o \
gt/intel_timeline.o \
+ gt/intel_tlb.o \
gt/intel_workarounds.o \
gt/shmem_utils.o \
gt/sysfs_engines.o
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_pages.c b/drivers/gpu/drm/i915/gem/i915_gem_pages.c
index 8357dbdcab5c..1cd76cc5d9f3 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_pages.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_pages.c
@@ -7,7 +7,7 @@
#include <drm/drm_cache.h>
#include "gt/intel_gt.h"
-#include "gt/intel_gt_pm.h"
+#include "gt/intel_tlb.h"
#include "i915_drv.h"
#include "i915_gem_object.h"
@@ -199,7 +199,7 @@ static void flush_tlb_invalidate(struct drm_i915_gem_object *obj)
if (!obj->mm.tlb)
return;
- intel_gt_invalidate_tlb(gt, obj->mm.tlb);
+ intel_gt_invalidate_tlb_full(gt, obj->mm.tlb);
obj->mm.tlb = 0;
}
diff --git a/drivers/gpu/drm/i915/gt/intel_gt.c b/drivers/gpu/drm/i915/gt/intel_gt.c
index f435e06125aa..18d82cd620bd 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt.c
+++ b/drivers/gpu/drm/i915/gt/intel_gt.c
@@ -11,9 +11,7 @@
#include "pxp/intel_pxp.h"
#include "i915_drv.h"
-#include "i915_perf_oa_regs.h"
#include "intel_context.h"
-#include "intel_engine_pm.h"
#include "intel_engine_regs.h"
#include "intel_ggtt_gmch.h"
#include "intel_gt.h"
@@ -31,6 +29,7 @@
#include "intel_renderstate.h"
#include "intel_rps.h"
#include "intel_gt_sysfs.h"
+#include "intel_tlb.h"
#include "intel_uncore.h"
#include "shmem_utils.h"
@@ -48,8 +47,7 @@ static void __intel_gt_init_early(struct intel_gt *gt)
intel_gt_init_reset(gt);
intel_gt_init_requests(gt);
intel_gt_init_timelines(gt);
- mutex_init(>->tlb.invalidate_lock);
- seqcount_mutex_init(>->tlb.seqno, >->tlb.invalidate_lock);
+ intel_gt_init_tlb(gt);
intel_gt_pm_init_early(gt);
intel_uc_init_early(>->uc);
@@ -770,7 +768,7 @@ void intel_gt_driver_late_release_all(struct drm_i915_private *i915)
intel_gt_fini_requests(gt);
intel_gt_fini_reset(gt);
intel_gt_fini_timelines(gt);
- mutex_destroy(>->tlb.invalidate_lock);
+ intel_gt_fini_tlb(gt);
intel_engines_free(gt);
}
}
@@ -881,163 +879,3 @@ void intel_gt_info_print(const struct intel_gt_info *info,
intel_sseu_dump(&info->sseu, p);
}
-
-struct reg_and_bit {
- i915_reg_t reg;
- u32 bit;
-};
-
-static struct reg_and_bit
-get_reg_and_bit(const struct intel_engine_cs *engine, const bool gen8,
- const i915_reg_t *regs, const unsigned int num)
-{
- const unsigned int class = engine->class;
- struct reg_and_bit rb = { };
-
- if (drm_WARN_ON_ONCE(&engine->i915->drm,
- class >= num || !regs[class].reg))
- return rb;
-
- rb.reg = regs[class];
- if (gen8 && class == VIDEO_DECODE_CLASS)
- rb.reg.reg += 4 * engine->instance; /* GEN8_M2TCR */
- else
- rb.bit = engine->instance;
-
- rb.bit = BIT(rb.bit);
-
- return rb;
-}
-
-static void mmio_invalidate_full(struct intel_gt *gt)
-{
- static const i915_reg_t gen8_regs[] = {
- [RENDER_CLASS] = GEN8_RTCR,
- [VIDEO_DECODE_CLASS] = GEN8_M1TCR, /* , GEN8_M2TCR */
- [VIDEO_ENHANCEMENT_CLASS] = GEN8_VTCR,
- [COPY_ENGINE_CLASS] = GEN8_BTCR,
- };
- static const i915_reg_t gen12_regs[] = {
- [RENDER_CLASS] = GEN12_GFX_TLB_INV_CR,
- [VIDEO_DECODE_CLASS] = GEN12_VD_TLB_INV_CR,
- [VIDEO_ENHANCEMENT_CLASS] = GEN12_VE_TLB_INV_CR,
- [COPY_ENGINE_CLASS] = GEN12_BLT_TLB_INV_CR,
- [COMPUTE_CLASS] = GEN12_COMPCTX_TLB_INV_CR,
- };
- struct drm_i915_private *i915 = gt->i915;
- struct intel_uncore *uncore = gt->uncore;
- struct intel_engine_cs *engine;
- intel_engine_mask_t awake, tmp;
- enum intel_engine_id id;
- const i915_reg_t *regs;
- unsigned int num = 0;
-
- if (GRAPHICS_VER(i915) == 12) {
- regs = gen12_regs;
- num = ARRAY_SIZE(gen12_regs);
- } else if (GRAPHICS_VER(i915) >= 8 && GRAPHICS_VER(i915) <= 11) {
- regs = gen8_regs;
- num = ARRAY_SIZE(gen8_regs);
- } else if (GRAPHICS_VER(i915) < 8) {
- return;
- }
-
- if (drm_WARN_ONCE(&i915->drm, !num,
- "Platform does not implement TLB invalidation!"))
- return;
-
- intel_uncore_forcewake_get(uncore, FORCEWAKE_ALL);
-
- spin_lock_irq(&uncore->lock); /* serialise invalidate with GT reset */
-
- awake = 0;
- for_each_engine(engine, gt, id) {
- struct reg_and_bit rb;
-
- if (!intel_engine_pm_is_awake(engine))
- continue;
-
- rb = get_reg_and_bit(engine, regs == gen8_regs, regs, num);
- if (!i915_mmio_reg_offset(rb.reg))
- continue;
-
- intel_uncore_write_fw(uncore, rb.reg, rb.bit);
- awake |= engine->mask;
- }
-
- GT_TRACE(gt, "invalidated engines %08x\n", awake);
-
- /* Wa_2207587034:tgl,dg1,rkl,adl-s,adl-p */
- if (awake &&
- (IS_TIGERLAKE(i915) ||
- IS_DG1(i915) ||
- IS_ROCKETLAKE(i915) ||
- IS_ALDERLAKE_S(i915) ||
- IS_ALDERLAKE_P(i915)))
- intel_uncore_write_fw(uncore, GEN12_OA_TLB_INV_CR, 1);
-
- spin_unlock_irq(&uncore->lock);
-
- for_each_engine_masked(engine, gt, awake, tmp) {
- struct reg_and_bit rb;
-
- /*
- * HW architecture suggest typical invalidation time at 40us,
- * with pessimistic cases up to 100us and a recommendation to
- * cap at 1ms. We go a bit higher just in case.
- */
- const unsigned int timeout_us = 100;
- const unsigned int timeout_ms = 4;
-
- rb = get_reg_and_bit(engine, regs == gen8_regs, regs, num);
- if (__intel_wait_for_register_fw(uncore,
- rb.reg, rb.bit, 0,
- timeout_us, timeout_ms,
- NULL))
- drm_err_ratelimited(>->i915->drm,
- "%s TLB invalidation did not complete in %ums!\n",
- engine->name, timeout_ms);
- }
-
- /*
- * Use delayed put since a) we mostly expect a flurry of TLB
- * invalidations so it is good to avoid paying the forcewake cost and
- * b) it works around a bug in Icelake which cannot cope with too rapid
- * transitions.
- */
- intel_uncore_forcewake_put_delayed(uncore, FORCEWAKE_ALL);
-}
-
-static bool tlb_seqno_passed(const struct intel_gt *gt, u32 seqno)
-{
- u32 cur = intel_gt_tlb_seqno(gt);
-
- /* Only skip if a *full* TLB invalidate barrier has passed */
- return (s32)(cur - ALIGN(seqno, 2)) > 0;
-}
-
-void intel_gt_invalidate_tlb(struct intel_gt *gt, u32 seqno)
-{
- intel_wakeref_t wakeref;
-
- if (I915_SELFTEST_ONLY(gt->awake == -ENODEV))
- return;
-
- if (intel_gt_is_wedged(gt))
- return;
-
- if (tlb_seqno_passed(gt, seqno))
- return;
-
- with_intel_gt_pm_if_awake(gt, wakeref) {
- mutex_lock(>->tlb.invalidate_lock);
- if (tlb_seqno_passed(gt, seqno))
- goto unlock;
-
- mmio_invalidate_full(gt);
-
- write_seqcount_invalidate(>->tlb.seqno);
-unlock:
- mutex_unlock(>->tlb.invalidate_lock);
- }
-}
diff --git a/drivers/gpu/drm/i915/gt/intel_gt.h b/drivers/gpu/drm/i915/gt/intel_gt.h
index 40b06adf509a..b4bba16cdb53 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt.h
+++ b/drivers/gpu/drm/i915/gt/intel_gt.h
@@ -101,16 +101,4 @@ void intel_gt_info_print(const struct intel_gt_info *info,
void intel_gt_watchdog_work(struct work_struct *work);
-static inline u32 intel_gt_tlb_seqno(const struct intel_gt *gt)
-{
- return seqprop_sequence(>->tlb.seqno);
-}
-
-static inline u32 intel_gt_next_invalidate_tlb_full(const struct intel_gt *gt)
-{
- return intel_gt_tlb_seqno(gt) | 1;
-}
-
-void intel_gt_invalidate_tlb(struct intel_gt *gt, u32 seqno);
-
#endif /* __INTEL_GT_H__ */
diff --git a/drivers/gpu/drm/i915/gt/intel_tlb.c b/drivers/gpu/drm/i915/gt/intel_tlb.c
new file mode 100644
index 000000000000..af8cae979489
--- /dev/null
+++ b/drivers/gpu/drm/i915/gt/intel_tlb.c
@@ -0,0 +1,183 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2022 Intel Corporation
+ */
+
+#include "i915_drv.h"
+#include "i915_perf_oa_regs.h"
+#include "intel_engine_pm.h"
+#include "intel_gt.h"
+#include "intel_gt_pm.h"
+#include "intel_gt_regs.h"
+#include "intel_tlb.h"
+
+struct reg_and_bit {
+ i915_reg_t reg;
+ u32 bit;
+};
+
+static struct reg_and_bit
+get_reg_and_bit(const struct intel_engine_cs *engine, const bool gen8,
+ const i915_reg_t *regs, const unsigned int num)
+{
+ const unsigned int class = engine->class;
+ struct reg_and_bit rb = { };
+
+ if (drm_WARN_ON_ONCE(&engine->i915->drm,
+ class >= num || !regs[class].reg))
+ return rb;
+
+ rb.reg = regs[class];
+ if (gen8 && class == VIDEO_DECODE_CLASS)
+ rb.reg.reg += 4 * engine->instance; /* GEN8_M2TCR */
+ else
+ rb.bit = engine->instance;
+
+ rb.bit = BIT(rb.bit);
+
+ return rb;
+}
+
+static bool tlb_seqno_passed(const struct intel_gt *gt, u32 seqno)
+{
+ u32 cur = intel_gt_tlb_seqno(gt);
+
+ /* Only skip if a *full* TLB invalidate barrier has passed */
+ return (s32)(cur - ALIGN(seqno, 2)) > 0;
+}
+
+static void mmio_invalidate_full(struct intel_gt *gt)
+{
+ static const i915_reg_t gen8_regs[] = {
+ [RENDER_CLASS] = GEN8_RTCR,
+ [VIDEO_DECODE_CLASS] = GEN8_M1TCR, /* , GEN8_M2TCR */
+ [VIDEO_ENHANCEMENT_CLASS] = GEN8_VTCR,
+ [COPY_ENGINE_CLASS] = GEN8_BTCR,
+ };
+ static const i915_reg_t gen12_regs[] = {
+ [RENDER_CLASS] = GEN12_GFX_TLB_INV_CR,
+ [VIDEO_DECODE_CLASS] = GEN12_VD_TLB_INV_CR,
+ [VIDEO_ENHANCEMENT_CLASS] = GEN12_VE_TLB_INV_CR,
+ [COPY_ENGINE_CLASS] = GEN12_BLT_TLB_INV_CR,
+ [COMPUTE_CLASS] = GEN12_COMPCTX_TLB_INV_CR,
+ };
+ struct drm_i915_private *i915 = gt->i915;
+ struct intel_uncore *uncore = gt->uncore;
+ struct intel_engine_cs *engine;
+ intel_engine_mask_t awake, tmp;
+ enum intel_engine_id id;
+ const i915_reg_t *regs;
+ unsigned int num = 0;
+
+ if (GRAPHICS_VER(i915) == 12) {
+ regs = gen12_regs;
+ num = ARRAY_SIZE(gen12_regs);
+ } else if (GRAPHICS_VER(i915) >= 8 && GRAPHICS_VER(i915) <= 11) {
+ regs = gen8_regs;
+ num = ARRAY_SIZE(gen8_regs);
+ } else if (GRAPHICS_VER(i915) < 8) {
+ return;
+ }
+
+ if (drm_WARN_ONCE(&i915->drm, !num,
+ "Platform does not implement TLB invalidation!"))
+ return;
+
+ intel_uncore_forcewake_get(uncore, FORCEWAKE_ALL);
+
+ spin_lock_irq(&uncore->lock); /* serialise invalidate with GT reset */
+
+ awake = 0;
+ for_each_engine(engine, gt, id) {
+ struct reg_and_bit rb;
+
+ if (!intel_engine_pm_is_awake(engine))
+ continue;
+
+ rb = get_reg_and_bit(engine, regs == gen8_regs, regs, num);
+ if (!i915_mmio_reg_offset(rb.reg))
+ continue;
+
+ intel_uncore_write_fw(uncore, rb.reg, rb.bit);
+ awake |= engine->mask;
+ }
+
+ GT_TRACE(gt, "invalidated engines %08x\n", awake);
+
+ /* Wa_2207587034:tgl,dg1,rkl,adl-s,adl-p */
+ if (awake &&
+ (IS_TIGERLAKE(i915) ||
+ IS_DG1(i915) ||
+ IS_ROCKETLAKE(i915) ||
+ IS_ALDERLAKE_S(i915) ||
+ IS_ALDERLAKE_P(i915)))
+ intel_uncore_write_fw(uncore, GEN12_OA_TLB_INV_CR, 1);
+
+ spin_unlock_irq(&uncore->lock);
+
+ for_each_engine_masked(engine, gt, awake, tmp) {
+ struct reg_and_bit rb;
+
+ /*
+ * HW architecture suggest typical invalidation time at 40us,
+ * with pessimistic cases up to 100us and a recommendation to
+ * cap at 1ms. We go a bit higher just in case.
+ */
+ const unsigned int timeout_us = 100;
+ const unsigned int timeout_ms = 4;
+
+ rb = get_reg_and_bit(engine, regs == gen8_regs, regs, num);
+ if (__intel_wait_for_register_fw(uncore,
+ rb.reg, rb.bit, 0,
+ timeout_us, timeout_ms,
+ NULL))
+ drm_err_ratelimited(>->i915->drm,
+ "%s TLB invalidation did not complete in %ums!\n",
+ engine->name, timeout_ms);
+ }
+
+ /*
+ * Use delayed put since a) we mostly expect a flurry of TLB
+ * invalidations so it is good to avoid paying the forcewake cost and
+ * b) it works around a bug in Icelake which cannot cope with too rapid
+ * transitions.
+ */
+ intel_uncore_forcewake_put_delayed(uncore, FORCEWAKE_ALL);
+}
+
+void intel_gt_invalidate_tlb_full(struct intel_gt *gt, u32 seqno)
+{
+ intel_wakeref_t wakeref;
+
+ if (I915_SELFTEST_ONLY(gt->awake == -ENODEV))
+ return;
+
+ if (intel_gt_is_wedged(gt))
+ return;
+
+ if (tlb_seqno_passed(gt, seqno))
+ return;
+
+ with_intel_gt_pm_if_awake(gt, wakeref) {
+ mutex_lock(>->tlb.invalidate_lock);
+ if (tlb_seqno_passed(gt, seqno))
+ goto unlock;
+
+ mmio_invalidate_full(gt);
+
+ write_seqcount_invalidate(>->tlb.seqno);
+unlock:
+ mutex_unlock(>->tlb.invalidate_lock);
+ }
+}
+
+void intel_gt_init_tlb(struct intel_gt *gt)
+{
+ mutex_init(>->tlb.invalidate_lock);
+ seqcount_mutex_init(>->tlb.seqno, >->tlb.invalidate_lock);
+}
+
+void intel_gt_fini_tlb(struct intel_gt *gt)
+{
+ mutex_destroy(>->tlb.invalidate_lock);
+}
diff --git a/drivers/gpu/drm/i915/gt/intel_tlb.h b/drivers/gpu/drm/i915/gt/intel_tlb.h
new file mode 100644
index 000000000000..46ce25bf5afe
--- /dev/null
+++ b/drivers/gpu/drm/i915/gt/intel_tlb.h
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright © 2022 Intel Corporation
+ */
+
+#ifndef INTEL_TLB_H
+#define INTEL_TLB_H
+
+#include <linux/seqlock.h>
+#include <linux/types.h>
+
+#include "intel_gt_types.h"
+
+void intel_gt_invalidate_tlb_full(struct intel_gt *gt, u32 seqno);
+
+void intel_gt_init_tlb(struct intel_gt *gt);
+void intel_gt_fini_tlb(struct intel_gt *gt);
+
+static inline u32 intel_gt_tlb_seqno(const struct intel_gt *gt)
+{
+ return seqprop_sequence(>->tlb.seqno);
+}
+
+static inline u32 intel_gt_next_invalidate_tlb_full(const struct intel_gt *gt)
+{
+ return intel_gt_tlb_seqno(gt) | 1;
+}
+
+#endif /* INTEL_TLB_H */
diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
index 84a9ccbc5fc5..fe947d1456d5 100644
--- a/drivers/gpu/drm/i915/i915_vma.c
+++ b/drivers/gpu/drm/i915/i915_vma.c
@@ -33,6 +33,7 @@
#include "gt/intel_engine_heartbeat.h"
#include "gt/intel_gt.h"
#include "gt/intel_gt_requests.h"
+#include "gt/intel_tlb.h"
#include "i915_drv.h"
#include "i915_gem_evict.h"
--
2.36.1
^ permalink raw reply related [flat|nested] 3+ messages in thread* [PATCH 2/2] drm/i915/gt: document TLB cache invalidation functions
2022-07-28 12:30 [PATCH 0/2] Move TLB invalidation code for its own file and document it Mauro Carvalho Chehab
2022-07-28 12:30 ` [PATCH 1/2] drm/i915/gt: Move TLB invalidation to its own file Mauro Carvalho Chehab
@ 2022-07-28 12:30 ` Mauro Carvalho Chehab
1 sibling, 0 replies; 3+ messages in thread
From: Mauro Carvalho Chehab @ 2022-07-28 12:30 UTC (permalink / raw)
Cc: Tvrtko Ursulin, David Airlie, dri-devel, linux-kernel,
Chris Wilson, Rodrigo Vivi, Mauro Carvalho Chehab, intel-gfx
Add a description for the TLB cache invalidation algorithm and for
the related kAPI functions.
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
---
To avoid mailbombing on a large number of people, only mailing lists were C/C on the cover.
See [PATCH 0/2] at: https://lore.kernel.org/all/cover.1659011328.git.mchehab@kernel.org/
drivers/gpu/drm/i915/gt/intel_tlb.c | 25 +++++++++
drivers/gpu/drm/i915/gt/intel_tlb.h | 83 +++++++++++++++++++++++++++++
2 files changed, 108 insertions(+)
diff --git a/drivers/gpu/drm/i915/gt/intel_tlb.c b/drivers/gpu/drm/i915/gt/intel_tlb.c
index af8cae979489..d5df2e0f77fb 100644
--- a/drivers/gpu/drm/i915/gt/intel_tlb.c
+++ b/drivers/gpu/drm/i915/gt/intel_tlb.c
@@ -145,6 +145,18 @@ static void mmio_invalidate_full(struct intel_gt *gt)
intel_uncore_forcewake_put_delayed(uncore, FORCEWAKE_ALL);
}
+/**
+ * intel_gt_invalidate_tlb_full - do full TLB cache invalidation
+ * @gt: GT structure
+ * @seqno: sequence number
+ *
+ * Do a full TLB cache invalidation if the @seqno is bigger than the last
+ * full TLB cache invalidation.
+ *
+ * Note:
+ * The TLB cache invalidation logic depends on GEN-specific registers.
+ * It currently supports GEN8 to GEN12 and GuC-based TLB cache invalidation.
+ */
void intel_gt_invalidate_tlb_full(struct intel_gt *gt, u32 seqno)
{
intel_wakeref_t wakeref;
@@ -171,12 +183,25 @@ void intel_gt_invalidate_tlb_full(struct intel_gt *gt, u32 seqno)
}
}
+/**
+ * intel_gt_init_tlb - initialize TLB-specific vars
+ * @gt: GT structure
+ *
+ * TLB cache invalidation logic internally uses some resources that require
+ * initialization. Should be called before doing any TLB cache invalidation.
+ */
void intel_gt_init_tlb(struct intel_gt *gt)
{
mutex_init(>->tlb.invalidate_lock);
seqcount_mutex_init(>->tlb.seqno, >->tlb.invalidate_lock);
}
+/**
+ * intel_gt_fini_tlb - initialize TLB-specific vars
+ * @gt: GT structure
+ *
+ * Frees any resources needed by TLB cache invalidation logic.
+ */
void intel_gt_fini_tlb(struct intel_gt *gt)
{
mutex_destroy(>->tlb.invalidate_lock);
diff --git a/drivers/gpu/drm/i915/gt/intel_tlb.h b/drivers/gpu/drm/i915/gt/intel_tlb.h
index 46ce25bf5afe..d186f5d5901f 100644
--- a/drivers/gpu/drm/i915/gt/intel_tlb.h
+++ b/drivers/gpu/drm/i915/gt/intel_tlb.h
@@ -11,16 +11,99 @@
#include "intel_gt_types.h"
+/**
+ * DOC: TLB cache invalidation logic
+ *
+ * The way the current algorithm works is that drm_i915_gem_object can be
+ * created on any order. At unbind/evict time, the object is warranted that
+ * it won't be used anymore. So, they store a sequence number provided by
+ * intel_gt_next_invalidate_tlb_full().This can happen either at
+ * __vma_put_pages(), for VMA sync unbind, or at ppgtt_unbind_vma(), for
+ * VMA async VMA bind.
+ *
+ * At __i915_gem_object_unset_pages(), intel_gt_invalidate_tlb() is called,
+ * where it checks if the sequence number of the object was already invalidated
+ * or not. If not, it increments it::
+ *
+ * void intel_gt_invalidate_tlb(struct intel_gt *gt, u32 seqno)
+ * {
+ * ...
+ * with_intel_gt_pm_if_awake(gt, wakeref) {
+ * mutex_lock(>->tlb.invalidate_lock);
+ * if (tlb_seqno_passed(gt, seqno))
+ * goto unlock;
+ *
+ * mmio_invalidate_full(gt);
+ *
+ * write_seqcount_invalidate(>->tlb.seqno); // increment seqno
+ * ...
+ *
+ * So, let's say the current seqno is 2 and 3 new objects were created,
+ * on this order:
+ *
+ * obj1
+ * obj2
+ * obj3
+ *
+ * They can be unbind/evict on a different order. At unbind/evict time,
+ * the mm.tlb will be stamped with the sequence number, using the number
+ * from the last TLB flush, plus 1.
+ *
+ * Different threads may be used on unbind/evict and/or unset pages.
+ *
+ * As the logic at void intel_gt_invalidate_tlb() is protected by a mutex,
+ * for simplicity, let's consider just two threads::
+ *
+ * sequence number Thread 0 Thread 1
+ *
+ * seqno=2
+ * unbind/evict event
+ * obj3.mm.tlb = seqno | 1
+ *
+ * unbind/evict event
+ * obj1.mm.tlb = seqno | 1
+ * __i915_gem_object_unset_pages()
+ * called for obj3 => TLB flush
+ * invalidating both obj1 and obj2.
+ * seqno += 2
+ * seqno=4
+ * unbind/evict event
+ * obj2.mm.tlb = seqno | 1
+ * __i915_gem_object_unset_pages()
+ * called for obj1, don't flush,
+ * as past flush invalidated obj1
+ *
+ * __i915_gem_object_unset_pages()
+ * called for obj2 => TLB flush
+ * seqno += 2
+ * seqno=6
+ */
+
void intel_gt_invalidate_tlb_full(struct intel_gt *gt, u32 seqno);
void intel_gt_init_tlb(struct intel_gt *gt);
void intel_gt_fini_tlb(struct intel_gt *gt);
+/**
+ * intel_gt_tlb_seqno - Returns the current TLB invlidation sequence number
+ *
+ * @gt: GT structure
+ *
+ * There's no need to lock while calling it, as seqprop_sequence is thread-safe
+ */
static inline u32 intel_gt_tlb_seqno(const struct intel_gt *gt)
{
return seqprop_sequence(>->tlb.seqno);
}
+/**
+ * intel_gt_next_invalidate_tlb_full - Returns the next TLB full invalidation
+ * sequence number
+ *
+ * @gt: GT structure
+ *
+ * There's no need to lock while calling it, as seqprop_sequence is thread-safe
+ */
static inline u32 intel_gt_next_invalidate_tlb_full(const struct intel_gt *gt)
{
return intel_gt_tlb_seqno(gt) | 1;
--
2.36.1
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