Re: [PATCH v3 3/9] drm/xe: Introduce GuC Doorbells Manager

["Piotr Piórkowski" <piotr.piorkowski@intel.com>]

Michal Wajdeczko <michal.wajdeczko@intel.com> wrote on pon [2023-gru-11 21:04:18 +0100]:
> The GFX doorbell solution provides a mechanism for submission of
> workload to the graphics hardware by a ring3 application without
> the penalty of ring transition for each workload submission.
> 
> This feature is not currently used by the Linux drivers, but in
> SR-IOV mode the doorbells are treated as shared resource and the
> PF driver must be able to provision exclusive range of doorbells
> IDs across all enabled VFs.
> 
> Introduce simple GuC doorbell ID manager that will be used by the
> PF driver for VFs provisioning and can later be used by submission
> code once we are ready to switch from H2G based notifications to
> doorbells mechanism.
> 
> Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
> Cc: Matthew Brost <matthew.brost@intel.com>
> Cc: Piotr Piórkowski <piotr.piorkowski@intel.com>
> 
> ---
> v2: fix renames, lock in fini
> v3: reorder init
> ---
>  drivers/gpu/drm/xe/Makefile        |   1 +
>  drivers/gpu/drm/xe/xe_guc_db_mgr.c | 257 +++++++++++++++++++++++++++++
>  drivers/gpu/drm/xe/xe_guc_db_mgr.h |  22 +++
>  drivers/gpu/drm/xe/xe_guc_types.h  |  15 ++
>  drivers/gpu/drm/xe/xe_uc.c         |   5 +
>  5 files changed, 300 insertions(+)
>  create mode 100644 drivers/gpu/drm/xe/xe_guc_db_mgr.c
>  create mode 100644 drivers/gpu/drm/xe/xe_guc_db_mgr.h
> 
> diff --git a/drivers/gpu/drm/xe/Makefile b/drivers/gpu/drm/xe/Makefile
> index f4ae063a7005..0c2e247dc188 100644
> --- a/drivers/gpu/drm/xe/Makefile
> +++ b/drivers/gpu/drm/xe/Makefile
> @@ -84,6 +84,7 @@ xe-y += xe_bb.o \
>  	xe_guc.o \
>  	xe_guc_ads.o \
>  	xe_guc_ct.o \
> +	xe_guc_db_mgr.o \
>  	xe_guc_debugfs.o \
>  	xe_guc_hwconfig.o \
>  	xe_guc_log.o \
> diff --git a/drivers/gpu/drm/xe/xe_guc_db_mgr.c b/drivers/gpu/drm/xe/xe_guc_db_mgr.c
> new file mode 100644
> index 000000000000..15816f90e960
> --- /dev/null
> +++ b/drivers/gpu/drm/xe/xe_guc_db_mgr.c
> @@ -0,0 +1,257 @@
> +// SPDX-License-Identifier: MIT
> +/*
> + * Copyright © 2023 Intel Corporation
> + */
> +
> +#include <linux/bitmap.h>
> +#include <linux/mutex.h>
> +
> +#include <drm/drm_managed.h>
> +
> +#include "regs/xe_guc_regs.h"
> +
> +#include "xe_assert.h"
> +#include "xe_gt_printk.h"
> +#include "xe_guc.h"
> +#include "xe_guc_db_mgr.h"
> +#include "xe_guc_types.h"
> +
> +/**
> + * DOC: GuC Doorbells
> + *
> + * The GFX doorbell solution provides a mechanism for submission of workload
> + * to the graphics hardware by a ring3 application without the penalty of
> + * ring transition for each workload submission.
> + *
> + * In SR-IOV mode, the doorbells are treated as shared resource and PF must
> + * be able to provision exclusive range of IDs across VFs, which may want to
> + * use this feature.
> + */
> +
> +static struct xe_guc *dbm_to_guc(struct xe_guc_db_mgr *dbm)
> +{
> +	return container_of(dbm, struct xe_guc, dbm);
> +}
> +
> +static struct xe_gt *dbm_to_gt(struct xe_guc_db_mgr *dbm)
> +{
> +	return guc_to_gt(dbm_to_guc(dbm));
> +}
> +
> +static struct xe_device *dbm_to_xe(struct xe_guc_db_mgr *dbm)
> +{
> +	return gt_to_xe(dbm_to_gt(dbm));
> +}
> +
> +#define dbm_assert(_dbm, _cond)		xe_gt_assert(dbm_to_gt(_dbm), _cond)
> +#define dbm_mutex(_dbm)			(&dbm_to_guc(_dbm)->submission_state.lock)
> +
> +static void __fini_dbm(struct drm_device *drm, void *arg)
> +{
> +	struct xe_guc_db_mgr *dbm = arg;
> +	unsigned int weight;
> +
> +	mutex_lock(dbm_mutex(dbm));
> +
> +	weight = bitmap_weight(dbm->bitmap, dbm->count);
> +	if (weight) {
> +		struct drm_printer p = xe_gt_info_printer(dbm_to_gt(dbm));
> +
> +		xe_gt_err(dbm_to_gt(dbm), "GuC doorbells manager unclean (%u/%u)\n",
> +			  weight, dbm->count);
> +		xe_guc_db_mgr_print(dbm, &p, 1);
> +	}
> +
> +	bitmap_free(dbm->bitmap);
> +	dbm->bitmap = NULL;
> +	dbm->count = 0;
> +
> +	mutex_unlock(dbm_mutex(dbm));
> +}
> +
> +/**
> + * xe_guc_db_mgr_init() - Initialize GuC Doorbells Manager.
> + * @dbm: the &xe_guc_db_mgr to initialize
> + * @count: number of doorbells to manage
> + *
> + * The bare-metal or PF driver can pass ~0 as &count to indicate that all
> + * doorbells supported by the hardware are available for use.
> + *
> + * Only VF's drivers will have to provide explicit number of doorbells IDs
> + * that they can use.
> + *
> + * Return: 0 on success or a negative error code on failure.
> + */
> +int xe_guc_db_mgr_init(struct xe_guc_db_mgr *dbm, unsigned int count)
> +{
> +	int ret;
> +
> +	if (count == ~0)
> +		count = GUC_NUM_DOORBELLS;
> +
> +	dbm_assert(dbm, !dbm->bitmap);
> +	dbm_assert(dbm, count <= GUC_NUM_DOORBELLS);
> +
> +	if (!count)
> +		goto done;
> +
> +	dbm->bitmap = bitmap_zalloc(count, GFP_KERNEL);
> +	if (!dbm->bitmap)
> +		return -ENOMEM;
> +	dbm->count = count;
> +
> +	ret = drmm_add_action_or_reset(&dbm_to_xe(dbm)->drm, __fini_dbm, dbm);
> +	if (ret)
> +		return ret;
> +done:
> +	xe_gt_dbg(dbm_to_gt(dbm), "using %u doorbell(s)\n", dbm->count);
> +	return 0;
> +}
> +
> +static int dbm_reserve_chunk_locked(struct xe_guc_db_mgr *dbm,
> +				    unsigned int count, unsigned int spare)
> +{
> +	unsigned int used;
> +	int index;
> +
> +	dbm_assert(dbm, count);
> +	dbm_assert(dbm, count <= GUC_NUM_DOORBELLS);
> +	dbm_assert(dbm, dbm->count <= GUC_NUM_DOORBELLS);
> +	lockdep_assert_held(dbm_mutex(dbm));
> +
> +	if (!dbm->count)
> +		return -ENODATA;
> +
> +	if (spare) {
> +		used = bitmap_weight(dbm->bitmap, dbm->count);
> +		if (used + count + spare > dbm->count)
> +			return -EDQUOT;
> +	}
> +
> +	index = bitmap_find_next_zero_area(dbm->bitmap, dbm->count, 0, count, 0);
> +	if (index >= dbm->count)
> +		return -ENOSPC;
> +
> +	bitmap_set(dbm->bitmap, index, count);
> +
> +	return index;
> +}
> +
> +static void dbm_release_chunk_locked(struct xe_guc_db_mgr *dbm,
> +				     unsigned int start, unsigned int count)
> +{
> +	dbm_assert(dbm, count);
> +	dbm_assert(dbm, count <= GUC_NUM_DOORBELLS);
> +	dbm_assert(dbm, dbm->count);
> +	dbm_assert(dbm, dbm->count <= GUC_NUM_DOORBELLS);
> +	lockdep_assert_held(dbm_mutex(dbm));
> +
> +	if (IS_ENABLED(CONFIG_DRM_XE_DEBUG)) {
> +		unsigned int n;
> +
> +		for (n = 0; n < count; n++)
> +			dbm_assert(dbm, test_bit(start + n, dbm->bitmap));
> +	}
> +	bitmap_clear(dbm->bitmap, start, count);
> +}
> +
> +/**
> + * xe_guc_db_mgr_reserve_id_locked() - Reserve a single GuC Doorbell ID.
> + * @dbm: the &xe_guc_db_mgr
> + *
> + * This function expects that submission lock is already taken.
> + *
> + * Return: ID of the allocated GuC doorbell or a negative error code on failure.
> + */
> +int xe_guc_db_mgr_reserve_id_locked(struct xe_guc_db_mgr *dbm)
> +{
> +	return dbm_reserve_chunk_locked(dbm, 1, 0);
> +}
> +
> +/**
> + * xe_guc_db_mgr_release_id_locked() - Release a single GuC Doorbell ID.
> + * @dbm: the &xe_guc_db_mgr
> + * @id: the GuC Doorbell ID to release
> + *
> + * This function expects that submission lock is already taken.
> + */
> +void xe_guc_db_mgr_release_id_locked(struct xe_guc_db_mgr *dbm, unsigned int id)
> +{
> +	return dbm_release_chunk_locked(dbm, id, 1);
> +}
> +
> +/**
> + * xe_guc_db_mgr_reserve_range() - Reserve a range of GuC Doorbell IDs.
> + * @dbm: the &xe_guc_db_mgr
> + * @count: number of GuC doorbell IDs to reserve
> + * @spare: number of GuC doorbell IDs to keep available
> + *
> + * This function is dedicated for the for use by the PF which expects that
> + * allocated range for the VF will be contiguous and that there will be at
> + * least &spare IDs still available for the PF use after this reservation.
> + *
> + * Return: starting ID of the allocated GuC doorbell ID range or
> + *         a negative error code on failure.
> + */
> +int xe_guc_db_mgr_reserve_range(struct xe_guc_db_mgr *dbm,
> +				unsigned int count, unsigned int spare)
> +{
> +	int ret;
> +
> +	mutex_lock(dbm_mutex(dbm));
> +	ret = dbm_reserve_chunk_locked(dbm, count, spare);
> +	mutex_unlock(dbm_mutex(dbm));
> +
> +	return ret;
> +}
> +
> +/**
> + * xe_guc_db_mgr_release_range() - Release a range of Doorbell IDs.
> + * @dbm: the &xe_guc_db_mgr
> + * @start: the starting ID of GuC doorbell ID range to release
> + * @count: number of GuC doorbell IDs to release
> + */
> +void xe_guc_db_mgr_release_range(struct xe_guc_db_mgr *dbm,
> +				 unsigned int start, unsigned int count)
> +{
> +	mutex_lock(dbm_mutex(dbm));
> +	dbm_release_chunk_locked(dbm, start, count);
> +	mutex_unlock(dbm_mutex(dbm));
> +}
> +
> +/**
> + * xe_guc_db_mgr_print() - Print status of GuC Doorbells Manager.
> + * @dbm: the &xe_guc_db_mgr to print
> + * @p: the &drm_printer to print to
> + * @indent: tab indentation level
> + */
> +void xe_guc_db_mgr_print(struct xe_guc_db_mgr *dbm,
> +			 struct drm_printer *p, int indent)
> +{
> +	unsigned int rs, re;
> +	unsigned int total;
> +
> +	drm_printf_indent(p, indent, "count: %u\n", dbm->count);
> +	if (!dbm->bitmap)
> +		return;
> +
> +	mutex_lock(dbm_mutex(dbm));
> +
> +	total = 0;
> +	for_each_clear_bitrange(rs, re, dbm->bitmap, dbm->count) {
> +		drm_printf_indent(p, indent, "available range: %u..%u (%u)\n",
> +				  rs, re - 1, re - rs);
> +		total += re - rs;
> +	}
> +	drm_printf_indent(p, indent, "available total: %u\n", total);
> +
> +	total = 0;
> +	for_each_set_bitrange(rs, re, dbm->bitmap, dbm->count) {
> +		drm_printf_indent(p, indent, "reserved range: %u..%u (%u)\n",
> +				  rs, re - 1, re - rs);
> +		total += re - rs;
> +	}
> +	drm_printf_indent(p, indent, "reserved total: %u\n", total);
> +
> +	mutex_unlock(dbm_mutex(dbm));
> +}
> diff --git a/drivers/gpu/drm/xe/xe_guc_db_mgr.h b/drivers/gpu/drm/xe/xe_guc_db_mgr.h
> new file mode 100644
> index 000000000000..c250fa0ca9d6
> --- /dev/null
> +++ b/drivers/gpu/drm/xe/xe_guc_db_mgr.h
> @@ -0,0 +1,22 @@
> +/* SPDX-License-Identifier: MIT */
> +/*
> + * Copyright © 2023 Intel Corporation
> + */
> +
> +#ifndef _XE_GUC_DB_MGR_H_
> +#define _XE_GUC_DB_MGR_H_
> +
> +struct drm_printer;
> +struct xe_guc_db_mgr;
> +
> +int xe_guc_db_mgr_init(struct xe_guc_db_mgr *dbm, unsigned int count);
> +
> +int xe_guc_db_mgr_reserve_id_locked(struct xe_guc_db_mgr *dbm);
> +void xe_guc_db_mgr_release_id_locked(struct xe_guc_db_mgr *dbm, unsigned int id);
> +
> +int xe_guc_db_mgr_reserve_range(struct xe_guc_db_mgr *dbm, unsigned int count, unsigned int spare);
> +void xe_guc_db_mgr_release_range(struct xe_guc_db_mgr *dbm, unsigned int start, unsigned int count);
> +
> +void xe_guc_db_mgr_print(struct xe_guc_db_mgr *dbm, struct drm_printer *p, int indent);
> +
> +#endif
> diff --git a/drivers/gpu/drm/xe/xe_guc_types.h b/drivers/gpu/drm/xe/xe_guc_types.h
> index cd80802e8918..16de203c62a7 100644
> --- a/drivers/gpu/drm/xe/xe_guc_types.h
> +++ b/drivers/gpu/drm/xe/xe_guc_types.h
> @@ -17,6 +17,19 @@
>  #include "xe_guc_pc_types.h"
>  #include "xe_uc_fw_types.h"
>  
> +/**
> + * struct xe_guc_db_mgr - GuC Doorbells Manager.
> + *
> + * Note: GuC Doorbells Manager is relying on &xe_guc::submission_state.lock
> + * to protect its members.
> + */
> +struct xe_guc_db_mgr {
> +	/** @count: number of doorbells to manage */
> +	unsigned int count;
> +	/** @bitmap: bitmap to track allocated doorbells */
> +	unsigned long *bitmap;
> +};
> +
>  /**
>   * struct xe_guc - Graphic micro controller
>   */
> @@ -31,6 +44,8 @@ struct xe_guc {
>  	struct xe_guc_ct ct;
>  	/** @pc: GuC Power Conservation */
>  	struct xe_guc_pc pc;
> +	/** @dbm: GuC Doorbell Manager */
> +	struct xe_guc_db_mgr dbm;
>  	/** @submission_state: GuC submission state */
>  	struct {
>  		/** @exec_queue_lookup: Lookup an xe_engine from guc_id */
> diff --git a/drivers/gpu/drm/xe/xe_uc.c b/drivers/gpu/drm/xe/xe_uc.c
> index 25e1ddfd2f86..4408ea1751e7 100644
> --- a/drivers/gpu/drm/xe/xe_uc.c
> +++ b/drivers/gpu/drm/xe/xe_uc.c
> @@ -9,6 +9,7 @@
>  #include "xe_gsc.h"
>  #include "xe_gt.h"
>  #include "xe_guc.h"
> +#include "xe_guc_db_mgr.h"
>  #include "xe_guc_pc.h"
>  #include "xe_guc_submit.h"
>  #include "xe_huc.h"
> @@ -60,6 +61,10 @@ int xe_uc_init(struct xe_uc *uc)
>  	if (ret)
>  		goto err;
>  
> +	ret = xe_guc_db_mgr_init(&uc->guc.dbm, ~0);
> +	if (ret)
> +		goto err;
> +
>  	return 0;

After the fixes you made, this series seems okay to me already:
Reviewed-by: Piotr Piórkowski <piotr.piorkowski@intel.com>


>  
>  err:
> -- 
> 2.25.1
> 

--