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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 470E8C6FD1D for ; Mon, 20 Mar 2023 17:47:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229749AbjCTRrs (ORCPT ); Mon, 20 Mar 2023 13:47:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34306 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229735AbjCTRrK (ORCPT ); Mon, 20 Mar 2023 13:47:10 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 0D8013B22A for ; Mon, 20 Mar 2023 10:42:48 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id DF5C015DB; Mon, 20 Mar 2023 10:28:11 -0700 (PDT) Received: from merodach.members.linode.com (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 6AF793F67D; Mon, 20 Mar 2023 10:27:25 -0700 (PDT) From: James Morse To: x86@kernel.org, linux-kernel@vger.kernel.org Cc: Fenghua Yu , Reinette Chatre , Thomas Gleixner , Ingo Molnar , Borislav Petkov , H Peter Anvin , Babu Moger , James Morse , shameerali.kolothum.thodi@huawei.com, D Scott Phillips OS , carl@os.amperecomputing.com, lcherian@marvell.com, bobo.shaobowang@huawei.com, tan.shaopeng@fujitsu.com, xingxin.hx@openanolis.org, baolin.wang@linux.alibaba.com, Jamie Iles , Xin Hao , peternewman@google.com Subject: [PATCH v3 06/19] x86/resctrl: Allow the allocator to check if a CLOSID can allocate clean RMID Date: Mon, 20 Mar 2023 17:26:07 +0000 Message-Id: <20230320172620.18254-7-james.morse@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20230320172620.18254-1-james.morse@arm.com> References: <20230320172620.18254-1-james.morse@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org MPAM's PMG bits extend its PARTID space, meaning the same PMG value can be used for different control groups. This means once a CLOSID is allocated, all its monitoring ids may still be dirty, and held in limbo. Add a helper to allow the CLOSID allocator to check if a CLOSID has dirty RMID values. This behaviour is enabled by a kconfig option selected by the architecture, which avoids a pointless search for x86. Tested-by: Shaopeng Tan Signed-off-by: James Morse --- Changes since v1: * Removed superflous IS_ENABLED(). Changes since v2: * Reworded comment over resctrl_closid_is_dirty() to reflect this is all RMID. --- arch/x86/kernel/cpu/resctrl/internal.h | 1 + arch/x86/kernel/cpu/resctrl/monitor.c | 36 ++++++++++++++++++++++++++ arch/x86/kernel/cpu/resctrl/rdtgroup.c | 17 +++++++----- 3 files changed, 47 insertions(+), 7 deletions(-) diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h index e11d9ce943d3..87545e4beb70 100644 --- a/arch/x86/kernel/cpu/resctrl/internal.h +++ b/arch/x86/kernel/cpu/resctrl/internal.h @@ -534,6 +534,7 @@ int rdtgroup_pseudo_lock_create(struct rdtgroup *rdtgrp); void rdtgroup_pseudo_lock_remove(struct rdtgroup *rdtgrp); struct rdt_domain *get_domain_from_cpu(int cpu, struct rdt_resource *r); int closids_supported(void); +bool resctrl_closid_is_dirty(u32 closid); void closid_free(int closid); int alloc_rmid(u32 closid); void free_rmid(u32 closid, u32 rmid); diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c index ca58a433c668..a2ae4be4b2ba 100644 --- a/arch/x86/kernel/cpu/resctrl/monitor.c +++ b/arch/x86/kernel/cpu/resctrl/monitor.c @@ -363,6 +363,42 @@ static struct rmid_entry *resctrl_find_free_rmid(u32 closid) return ERR_PTR(-ENOSPC); } +/** + * resctrl_closid_is_dirty - Determine if all RMID associated with this CLOSID + * are available. + * @closid: The CLOSID that is being queried. + * + * MPAM's equivalent of RMID are per-CLOSID, meaning a freshly allocated CLOSID + * may not be able to allocate clean RMID. To avoid this the allocator will + * only return clean CLOSID. This is enough for now as it allows MPAM systems + * to use resctrl. This suffers from the problem that there may be no CLOSID + * where all the RMID are clean, causing the CLOSID allocation to fail. + * This can be improved (once MPAM support is upstream) to return the cleanest + * CLOSID where PMG=0 is clean. This would allow the CLOSID allocation to + * succeed, but subsequent monitor-group allocations may fail. + */ +bool resctrl_closid_is_dirty(u32 closid) +{ + struct rmid_entry *entry; + int i; + + lockdep_assert_held(&rdtgroup_mutex); + + if (!IS_ENABLED(CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID)) + return false; + + for (i = 0; i < resctrl_arch_system_num_rmid_idx(); i++) { + entry = &rmid_ptrs[i]; + if (entry->closid != closid) + continue; + + if (entry->busy) + return true; + } + + return false; +} + /* * For MPAM the RMID value is not unique, and has to be considered with * the CLOSID. The (CLOSID, RMID) pair is allocated on all domains, which diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c index bcd27610bb77..e741bc47bae9 100644 --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c @@ -93,7 +93,7 @@ void rdt_last_cmd_printf(const char *fmt, ...) * - Our choices on how to configure each resource become progressively more * limited as the number of resources grows. */ -static int closid_free_map; +static unsigned long closid_free_map; static int closid_free_map_len; int closids_supported(void) @@ -119,14 +119,17 @@ static void closid_init(void) static int closid_alloc(void) { - u32 closid = ffs(closid_free_map); + u32 closid; - if (closid == 0) - return -ENOSPC; - closid--; - closid_free_map &= ~(1 << closid); + for_each_set_bit(closid, &closid_free_map, closid_free_map_len) { + if (resctrl_closid_is_dirty(closid)) + continue; - return closid; + clear_bit(closid, &closid_free_map); + return closid; + } + + return -ENOSPC; } void closid_free(int closid) -- 2.39.2