From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 13F11C678D4 for ; Mon, 6 Mar 2023 13:18:11 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id E3F5710E0BB; Mon, 6 Mar 2023 13:18:10 +0000 (UTC) Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by gabe.freedesktop.org (Postfix) with ESMTPS id F33AE10E0BB for ; Mon, 6 Mar 2023 13:18:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1678108689; x=1709644689; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=rEHqymnCoY0zYM39SqjB5BV61f73Xv+nu0lAkbpZTFw=; b=C/5Q6vQ/iikXyv+zKK42pR82P4CioR5Y7sO9AL+ROiTGCs5dEAk2z7WX A4DHyrUnUQiwyC3Vf85b+NT1178Qx2p7JsM6h918R9i7ft1JaekyX5rJi YibU1cwYOp84a+deh1RvF6nXeB7UgYuz8XIbXr8xRq0R3P1dDYavwSiI/ lIV8S7dUWCnrSPido7AuQ4cHu9C56BOxCCCv5zdiPGbgiqhxVFtuBJi3L ywRGIV1FN3LxKEwPyerC+yL4QYnWv4XcQDVaf98N8TMD4IhddqGB/Zq9T LPtADTR0ZDUnBsuW8FGJjI6e05Q6hndaVJ4gD6MaRQRr76SDxSXUku6hb Q==; X-IronPort-AV: E=McAfee;i="6500,9779,10640"; a="337866695" X-IronPort-AV: E=Sophos;i="5.98,236,1673942400"; d="scan'208";a="337866695" Received: from orsmga006.jf.intel.com ([10.7.209.51]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Mar 2023 05:18:04 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6500,9779,10640"; a="653607203" X-IronPort-AV: E=Sophos;i="5.98,236,1673942400"; d="scan'208";a="653607203" Received: from jsyrstad-mobl1.amr.corp.intel.com (HELO thellstr-mobl1.intel.com) ([10.249.254.109]) by orsmga006-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Mar 2023 05:18:03 -0800 From: =?UTF-8?q?Thomas=20Hellstr=C3=B6m?= To: intel-xe@lists.freedesktop.org Date: Mon, 6 Mar 2023 14:17:36 +0100 Message-Id: <20230306131738.197862-2-thomas.hellstrom@linux.intel.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230306131738.197862-1-thomas.hellstrom@linux.intel.com> References: <20230306131738.197862-1-thomas.hellstrom@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Subject: [Intel-xe] [PATCH 1/3] drm/xe: Add a page-table walker X-BeenThere: intel-xe@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel Xe graphics driver List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-xe-bounces@lists.freedesktop.org Sender: "Intel-xe" Add a gpu page table walker similar in functionality to the cpu page-table walker in mm/pagewalk.c. This is a candidate for being drm-generic if there are other drivers that may find it useful so should, if possible, be preserved in that way. Signed-off-by: Thomas Hellström --- drivers/gpu/drm/xe/Makefile | 1 + drivers/gpu/drm/xe/xe_pt_walk.c | 160 +++++++++++++++++++++++++++++++ drivers/gpu/drm/xe/xe_pt_walk.h | 161 ++++++++++++++++++++++++++++++++ 3 files changed, 322 insertions(+) create mode 100644 drivers/gpu/drm/xe/xe_pt_walk.c create mode 100644 drivers/gpu/drm/xe/xe_pt_walk.h diff --git a/drivers/gpu/drm/xe/Makefile b/drivers/gpu/drm/xe/Makefile index 18257cd7227d..49460a3ec12c 100644 --- a/drivers/gpu/drm/xe/Makefile +++ b/drivers/gpu/drm/xe/Makefile @@ -75,6 +75,7 @@ xe-y += xe_bb.o \ xe_pm.o \ xe_preempt_fence.o \ xe_pt.o \ + xe_pt_walk.o \ xe_query.o \ xe_reg_sr.o \ xe_reg_whitelist.o \ diff --git a/drivers/gpu/drm/xe/xe_pt_walk.c b/drivers/gpu/drm/xe/xe_pt_walk.c new file mode 100644 index 000000000000..0def89af4372 --- /dev/null +++ b/drivers/gpu/drm/xe/xe_pt_walk.c @@ -0,0 +1,160 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright © 2022 Intel Corporation + */ +#include "xe_pt_walk.h" + +/** + * DOC: GPU page-table tree walking. + * The utilities in this file are similar to the CPU page-table walk + * utilities in mm/pagewalk.c. The main difference is that we distinguish + * the various levels of a page-table tree with an unsigned integer rather + * than by name. 0 is the lowest level, and page-tables with level 0 can + * not be directories pointing to lower levels, whereas all other levels + * can. The user of the utilities determines the highest level. + * + * Nomenclature: + * Each struct xe_ptw, regardless of level is referred to as a page table, and + * multiple page tables typically form a page table tree with page tables at + * intermediate levels being page directories pointing at page tables at lower + * levels. A shared page table for a given address range is a page-table which + * is neither fully within nor fully outside the address range and that can + * thus be shared by two or more address ranges. + * + * Please keep this code generic so that it can used as a drm-wide page- + * table walker should other drivers find use for it. + */ +static u64 xe_pt_addr_end(u64 addr, u64 end, unsigned int level, + const struct xe_pt_walk *walk) +{ + u64 size = 1ull << walk->shifts[level]; + u64 tmp = round_up(addr + 1, size); + + return min_t(u64, tmp, end); +} + +static bool xe_pt_next(pgoff_t *offset, u64 *addr, u64 next, u64 end, + unsigned int level, const struct xe_pt_walk *walk) +{ + pgoff_t step = 1; + + /* Shared pt walk skips to the last pagetable */ + if (unlikely(walk->shared_pt_mode)) { + unsigned int shift = walk->shifts[level]; + u64 skip_to = round_down(end, 1ull << shift); + + if (skip_to > next) { + step += (skip_to - next) >> shift; + next = skip_to; + } + } + + *addr = next; + *offset += step; + + return next != end; +} + +/** + * xe_pt_walk_range() - Walk a range of a gpu page table tree with callbacks + * for each page-table entry in all levels. + * @parent: The root page table for walk start. + * @level: The root page table level. + * @addr: Virtual address start. + * @end: Virtual address end + 1. + * @walk: Walk info. + * + * Similar to the CPU page-table walker, this is a helper to walk + * a gpu page table and call a provided callback function for each entry. + * + * Return: 0 on success, negative error code on error. The error is + * propagated from the callback and on error the walk is terminated. + */ +int xe_pt_walk_range(struct xe_ptw *parent, unsigned int level, + u64 addr, u64 end, struct xe_pt_walk *walk) +{ + pgoff_t offset = xe_pt_offset(addr, level, walk); + struct xe_ptw **entries = parent->dir ? parent->dir->entries : NULL; + const struct xe_pt_walk_ops *ops = walk->ops; + enum page_walk_action action; + struct xe_ptw *child; + int err = 0; + u64 next; + + do { + next = xe_pt_addr_end(addr, end, level, walk); + if (walk->shared_pt_mode && xe_pt_covers(addr, next, level, + walk)) + continue; +again: + action = ACTION_SUBTREE; + child = entries ? entries[offset] : NULL; + err = ops->pt_entry(parent, offset, level, addr, next, + &child, &action, walk); + if (err) + break; + + /* Probably not needed yet for gpu pagetable walk. */ + if (unlikely(action == ACTION_AGAIN)) + goto again; + + if (likely(!level || !child || action == ACTION_CONTINUE)) + continue; + + err = xe_pt_walk_range(child, level - 1, addr, next, walk); + + if (!err && ops->pt_post_descend) + err = ops->pt_post_descend(parent, offset, level, addr, + next, &child, &action, walk); + if (err) + break; + + } while (xe_pt_next(&offset, &addr, next, end, level, walk)); + + return err; +} + +/** + * xe_pt_walk_shared() - Walk shared page tables of a page-table tree. + * @parent: Root page table directory. + * @level: Level of the root. + * @addr: Start address. + * @end: Last address + 1. + * @walk: Walk info. + * + * This function is similar to xe_pt_walk_range() but it skips page tables + * that are private to the range. Since the root (or @parent) page table is + * typically also a shared page table this function is different in that it + * calls the pt_entry callback and the post_descend callback also for the + * root. The root can be detected in the callbacks by checking whether + * parent == *child. + * Walking only the shared page tables is common for unbind-type operations + * where the page-table entries for an address range are cleared or detached + * from the main page-table tree. + * + * Return: 0 on success, negative error code on error: If a callback + * returns an error, the walk will be terminated and the error returned by + * this function. + */ +int xe_pt_walk_shared(struct xe_ptw *parent, unsigned int level, + u64 addr, u64 end, struct xe_pt_walk *walk) +{ + const struct xe_pt_walk_ops *ops = walk->ops; + enum page_walk_action action = ACTION_SUBTREE; + struct xe_ptw *child = parent; + int err; + + walk->shared_pt_mode = true; + err = walk->ops->pt_entry(parent, 0, level + 1, addr, end, + &child, &action, walk); + + if (err || action != ACTION_SUBTREE) + return err; + + err = xe_pt_walk_range(parent, level, addr, end, walk); + if (!err && ops->pt_post_descend) { + err = ops->pt_post_descend(parent, 0, level + 1, addr, end, + &child, &action, walk); + } + return err; +} diff --git a/drivers/gpu/drm/xe/xe_pt_walk.h b/drivers/gpu/drm/xe/xe_pt_walk.h new file mode 100644 index 000000000000..42c51fa601ec --- /dev/null +++ b/drivers/gpu/drm/xe/xe_pt_walk.h @@ -0,0 +1,161 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright © 2022 Intel Corporation + */ +#ifndef __XE_PT_WALK__ +#define __XE_PT_WALK__ + +#include +#include + +struct xe_ptw_dir; + +/** + * struct xe_ptw - base class for driver pagetable subclassing. + * @dir: Pointer to an array of children if any. + * + * Drivers could subclass this, and if it's a page-directory, typically + * embed the xe_ptw_dir::entries array in the same allocation. + */ +struct xe_ptw { + struct xe_ptw_dir *dir; +}; + +/** + * struct xe_ptw_dir - page directory structure + * @entries: Array holding page directory children. + * + * It is the responsibility of the user to ensure @entries is + * correctly sized. + */ +struct xe_ptw_dir { + struct xe_ptw *entries[0]; +}; + +/** + * struct xe_pt_walk - Embeddable struct for walk parameters + */ +struct xe_pt_walk { + /** @ops: The walk ops used for the pagewalk */ + const struct xe_pt_walk_ops *ops; + /** + * @shifts: Array of page-table entry shifts used for the + * different levels, starting out with the leaf level 0 + * page-shift as the first entry. It's legal for this pointer to be + * changed during the walk. + */ + const u64 *shifts; + /** @max_level: Highest populated level in @sizes */ + unsigned int max_level; + /** + * @shared_pt_mode: Whether to skip all entries that are private + * to the address range and called only for entries that are + * shared with other address ranges. Such entries are referred to + * as shared pagetables. + */ + bool shared_pt_mode; +}; + +/** + * typedef xe_pt_entry_fn - gpu page-table-walk callback-function + * @parent: The parent page.table. + * @offset: The offset (number of entries) into the page table. + * @level: The level of @parent. + * @addr: The virtual address. + * @next: The virtual address for the next call, or end address. + * @child: Pointer to pointer to child page-table at this @offset. The + * function may modify the value pointed to if, for example, allocating a + * child page table. + * @action: The walk action to take upon return. See . + * @walk: The walk parameters. + */ +typedef int (*xe_pt_entry_fn)(struct xe_ptw *parent, pgoff_t offset, + unsigned int level, u64 addr, u64 next, + struct xe_ptw **child, + enum page_walk_action *action, + struct xe_pt_walk *walk); + +/** + * struct xe_pt_walk_ops - Walk callbacks. + */ +struct xe_pt_walk_ops { + /** + * @pt_entry: Callback to be called for each page table entry prior + * to descending to the next level. The returned value of the action + * function parameter is honored. + */ + xe_pt_entry_fn pt_entry; + /** + * @pt_post_descend: Callback to be called for each page table entry + * after return from descending to the next level. The returned value + * of the action function parameter is ignored. + */ + xe_pt_entry_fn pt_post_descend; +}; + +int xe_pt_walk_range(struct xe_ptw *parent, unsigned int level, + u64 addr, u64 end, struct xe_pt_walk *walk); + +int xe_pt_walk_shared(struct xe_ptw *parent, unsigned int level, + u64 addr, u64 end, struct xe_pt_walk *walk); + +/** + * xe_pt_covers - Whether the address range covers an entire entry in @level + * @addr: Start of the range. + * @end: End of range + 1. + * @level: Page table level. + * @walk: Page table walk info. + * + * This function is a helper to aid in determining whether a leaf page table + * entry can be inserted at this @level. + * + * Return: Whether the range provided covers exactly an entry at this level. + */ +static inline bool xe_pt_covers(u64 addr, u64 end, unsigned int level, + const struct xe_pt_walk *walk) +{ + u64 pt_size = 1ull << walk->shifts[level]; + + return end - addr == pt_size && IS_ALIGNED(addr, pt_size); +} + +/** + * xe_pt_num_entries: Number of page-table entries of a given range at this + * level + * @addr: Start address. + * @end: End address. + * @level: Page table level. + * @walk: Walk info. + * + * Return: The number of page table entries at this level between @start and + * @end. + */ +static inline pgoff_t +xe_pt_num_entries(u64 addr, u64 end, unsigned int level, + const struct xe_pt_walk *walk) +{ + u64 pt_size = 1ull << walk->shifts[level]; + + return (round_up(end, pt_size) - round_down(addr, pt_size)) >> + walk->shifts[level]; +} + +/** + * xe_pt_offset: Offset of the page-table entry for a given address. + * @addr: The address. + * @level: Page table level. + * @walk: Walk info. + * + * Return: The page table entry offset for the given address in a + * page table with size indicated by @level. + */ +static inline pgoff_t +xe_pt_offset(u64 addr, unsigned int level, const struct xe_pt_walk *walk) +{ + if (level < walk->max_level) + addr &= ((1ull << walk->shifts[level + 1]) - 1); + + return addr >> walk->shifts[level]; +} + +#endif -- 2.39.2