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 X-Spam-Level: X-Spam-Status: No, score=-8.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E6BC3C48BE3 for ; Thu, 20 Jun 2019 13:06:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C2EB52082C for ; Thu, 20 Jun 2019 13:06:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732095AbfFTNGz (ORCPT ); Thu, 20 Jun 2019 09:06:55 -0400 Received: from foss.arm.com ([217.140.110.172]:36844 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726758AbfFTNGn (ORCPT ); Thu, 20 Jun 2019 09:06:43 -0400 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 72B15C0A; Thu, 20 Jun 2019 06:06:43 -0700 (PDT) Received: from e108454-lin.cambridge.arm.com (e108454-lin.cambridge.arm.com [10.1.196.50]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 035B53F718; Thu, 20 Jun 2019 06:06:41 -0700 (PDT) From: Julien Grall To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu Cc: james.morse@arm.com, marc.zyngier@arm.com, julien.thierry@arm.com, suzuki.poulose@arm.com, catalin.marinas@arm.com, will.deacon@arm.com, Julien Grall , Russell King Subject: [RFC v2 13/14] arm/kvm: Introduce a new VMID allocator Date: Thu, 20 Jun 2019 14:06:07 +0100 Message-Id: <20190620130608.17230-14-julien.grall@arm.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20190620130608.17230-1-julien.grall@arm.com> References: <20190620130608.17230-1-julien.grall@arm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org A follow-up patch will replace the KVM VMID allocator with the arm64 ASID allocator. To avoid as much as possible duplication, the arm KVM code will directly compile arch/arm64/lib/asid.c. The header is a verbatim to copy to avoid breaking the assumption that architecture port has self-containers headers. Signed-off-by: Julien Grall Cc: Russell King --- I hit a warning when compiling the ASID code: linux/arch/arm/kvm/../../arm64/lib/asid.c:17: warning: "ASID_MASK" redefined #define ASID_MASK(info) (~GENMASK((info)->bits - 1, 0)) In file included from linux/include/linux/mm_types.h:18, from linux/include/linux/mmzone.h:21, from linux/include/linux/gfp.h:6, from linux/include/linux/slab.h:15, from linux/arch/arm/kvm/../../arm64/lib/asid.c:11: linux/arch/arm/include/asm/mmu.h:26: note: this is the location of the previous definition #define ASID_MASK ((~0ULL) << ASID_BITS) I haven't yet resolved because I am not sure of the best way to go. AFAICT ASID_MASK is only used in mm/context.c. So I am wondering whether it would be acceptable to move the define. Changes in v2: - Re-use arm64/lib/asid.c rather than duplication the code. --- arch/arm/include/asm/lib_asid.h | 81 +++++++++++++++++++++++++++++++++++++++++ arch/arm/kvm/Makefile | 1 + 2 files changed, 82 insertions(+) create mode 100644 arch/arm/include/asm/lib_asid.h diff --git a/arch/arm/include/asm/lib_asid.h b/arch/arm/include/asm/lib_asid.h new file mode 100644 index 000000000000..79bce4686d21 --- /dev/null +++ b/arch/arm/include/asm/lib_asid.h @@ -0,0 +1,81 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __ARM_LIB_ASID_H__ +#define __ARM_LIB_ASID_H__ + +#include +#include +#include +#include +#include + +struct asid_info +{ + atomic64_t generation; + unsigned long *map; + atomic64_t __percpu *active; + u64 __percpu *reserved; + u32 bits; + /* Lock protecting the structure */ + raw_spinlock_t lock; + /* Which CPU requires context flush on next call */ + cpumask_t flush_pending; + /* Number of ASID allocated by context (shift value) */ + unsigned int ctxt_shift; + /* Callback to locally flush the context. */ + void (*flush_cpu_ctxt_cb)(void); + /* Callback to call when a context is updated */ + void (*update_ctxt_cb)(void *ctxt); +}; + +#define NUM_ASIDS(info) (1UL << ((info)->bits)) +#define NUM_CTXT_ASIDS(info) (NUM_ASIDS(info) >> (info)->ctxt_shift) + +#define active_asid(info, cpu) *per_cpu_ptr((info)->active, cpu) + +void asid_new_context(struct asid_info *info, atomic64_t *pasid, + unsigned int cpu, void *ctxt); + +/* + * Check the ASID is still valid for the context. If not generate a new ASID. + * + * @pasid: Pointer to the current ASID batch + * @cpu: current CPU ID. Must have been acquired throught get_cpu() + */ +static inline void asid_check_context(struct asid_info *info, + atomic64_t *pasid, unsigned int cpu, + void *ctxt) +{ + u64 asid, old_active_asid; + + asid = atomic64_read(pasid); + + /* + * The memory ordering here is subtle. + * If our active_asid is non-zero and the ASID matches the current + * generation, then we update the active_asid entry with a relaxed + * cmpxchg. Racing with a concurrent rollover means that either: + * + * - We get a zero back from the cmpxchg and end up waiting on the + * lock. Taking the lock synchronises with the rollover and so + * we are forced to see the updated generation. + * + * - We get a valid ASID back from the cmpxchg, which means the + * relaxed xchg in flush_context will treat us as reserved + * because atomic RmWs are totally ordered for a given location. + */ + old_active_asid = atomic64_read(&active_asid(info, cpu)); + if (old_active_asid && + !((asid ^ atomic64_read(&info->generation)) >> info->bits) && + atomic64_cmpxchg_relaxed(&active_asid(info, cpu), + old_active_asid, asid)) + return; + + asid_new_context(info, pasid, cpu, ctxt); +} + +int asid_allocator_init(struct asid_info *info, + u32 bits, unsigned int asid_per_ctxt, + void (*flush_cpu_ctxt_cb)(void), + void (*update_ctxt_cb)(void *ctxt)); + +#endif /* __ARM_LIB_ASID_H__ */ diff --git a/arch/arm/kvm/Makefile b/arch/arm/kvm/Makefile index 531e59f5be9c..6ab49bd84531 100644 --- a/arch/arm/kvm/Makefile +++ b/arch/arm/kvm/Makefile @@ -40,3 +40,4 @@ obj-y += $(KVM)/arm/vgic/vgic-its.o obj-y += $(KVM)/arm/vgic/vgic-debug.o obj-y += $(KVM)/irqchip.o obj-y += $(KVM)/arm/arch_timer.o +obj-y += ../../arm64/lib/asid.o -- 2.11.0