From patchwork Fri May 19 10:21:08 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Zijlstra X-Patchwork-Id: 13248181 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 02396C77B7F for ; Fri, 19 May 2023 10:34:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232033AbjESKem (ORCPT ); Fri, 19 May 2023 06:34:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53804 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231963AbjESKeV (ORCPT ); Fri, 19 May 2023 06:34:21 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EE47B10E9; Fri, 19 May 2023 03:34:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Type:MIME-Version:References: Subject:Cc:To:From:Date:Message-ID:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:In-Reply-To; bh=jRlOPCiGZ1QUnD3ip/ciK1dDyTis2uNLJ5A1APQzhgQ=; b=Dzv1GYHGnPXTBnG4o/Xs2ei8aB Q4Q6AnwKkhA4/hEfC+CyMGueM2yEEVQV5k5/e+DpKX7iQH+uIsaifb3r5hun1Lb7Ut3RbjPW/FK3q 7GgHVmd0difqEDkcOUBcHAAh5c6uRhVnesPdDrMRNy/o6AnRENKyjOblNglpALQqDQc/2Nn6ie6+b ucFkxiKZvHRfSu80GKiNvsUh8ymS2G3cSlbSyOZ+URcvm9aZHO7ZGRSM/eu5b4omZrZLj+4rqNVY9 AKoPw+lovjejVC3kt7P8jMHh8B13s8koFqJH7ULD9r3B+YQXXFeiaQspwGhIId5AKB0TqQ/qGFkBs ApoGTrcA==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1pzxPv-006UqQ-LP; Fri, 19 May 2023 10:33:00 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 3C81430614C; Fri, 19 May 2023 12:32:56 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 0) id E61E9235EF0B3; Fri, 19 May 2023 12:32:55 +0200 (CEST) Message-ID: <20230519102715.843039089@infradead.org> User-Agent: quilt/0.66 Date: Fri, 19 May 2023 12:21:08 +0200 From: Peter Zijlstra To: bigeasy@linutronix.de Cc: mark.rutland@arm.com, maz@kernel.org, catalin.marinas@arm.com, will@kernel.org, chenhuacai@kernel.org, kernel@xen0n.name, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, pbonzini@redhat.com, wanpengli@tencent.com, vkuznets@redhat.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, jgross@suse.com, boris.ostrovsky@oracle.com, daniel.lezcano@linaro.org, kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, rafael@kernel.org, peterz@infradead.org, longman@redhat.com, boqun.feng@gmail.com, pmladek@suse.com, senozhatsky@chromium.org, rostedt@goodmis.org, john.ogness@linutronix.de, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com, jstultz@google.com, sboyd@kernel.org, linux-kernel@vger.kernel.org, loongarch@lists.linux.dev, linux-s390@vger.kernel.org, kvm@vger.kernel.org, linux-hyperv@vger.kernel.org, linux-pm@vger.kernel.org, Michael Kelley Subject: [PATCH v2 10/13] clocksource: hyper-v: Provide noinstr sched_clock() References: <20230519102058.581557770@infradead.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org With the intent to provide local_clock_noinstr(), a variant of local_clock() that's safe to be called from noinstr code (with the assumption that any such code will already be non-preemptible), prepare for things by making the Hyper-V TSC and MSR sched_clock implementations noinstr. Signed-off-by: Peter Zijlstra (Intel) Co-developed-by: Michael Kelley Signed-off-by: Michael Kelley Signed-off-by: Peter Zijlstra (Intel) --- arch/x86/include/asm/mshyperv.h | 5 +++++ drivers/clocksource/hyperv_timer.c | 32 ++++++++++++++++++-------------- 2 files changed, 23 insertions(+), 14 deletions(-) --- a/arch/x86/include/asm/mshyperv.h +++ b/arch/x86/include/asm/mshyperv.h @@ -257,6 +257,11 @@ void hv_set_register(unsigned int reg, u u64 hv_get_non_nested_register(unsigned int reg); void hv_set_non_nested_register(unsigned int reg, u64 value); +static __always_inline u64 hv_raw_get_register(unsigned int reg) +{ + return __rdmsr(reg); +} + #else /* CONFIG_HYPERV */ static inline void hyperv_init(void) {} static inline void hyperv_setup_mmu_ops(void) {} --- a/drivers/clocksource/hyperv_timer.c +++ b/drivers/clocksource/hyperv_timer.c @@ -365,6 +365,20 @@ void hv_stimer_global_cleanup(void) } EXPORT_SYMBOL_GPL(hv_stimer_global_cleanup); +static __always_inline u64 read_hv_clock_msr(void) +{ + /* + * Read the partition counter to get the current tick count. This count + * is set to 0 when the partition is created and is incremented in 100 + * nanosecond units. + * + * Use hv_raw_get_register() because this function is used from + * noinstr. Notable; while HV_REGISTER_TIME_REF_COUNT is a synthetic + * register it doesn't need the GHCB path. + */ + return hv_raw_get_register(HV_REGISTER_TIME_REF_COUNT); +} + /* * Code and definitions for the Hyper-V clocksources. Two * clocksources are defined: one that reads the Hyper-V defined MSR, and @@ -393,7 +407,7 @@ struct ms_hyperv_tsc_page *hv_get_tsc_pa } EXPORT_SYMBOL_GPL(hv_get_tsc_page); -static notrace u64 read_hv_clock_tsc(void) +static __always_inline u64 read_hv_clock_tsc(void) { u64 cur_tsc, time; @@ -404,7 +418,7 @@ static notrace u64 read_hv_clock_tsc(voi * to the MSR in case the TSC page indicates unavailability. */ if (!hv_read_tsc_page_tsc(tsc_page, &cur_tsc, &time)) - time = hv_get_register(HV_REGISTER_TIME_REF_COUNT); + time = read_hv_clock_msr(); return time; } @@ -414,7 +428,7 @@ static u64 notrace read_hv_clock_tsc_cs( return read_hv_clock_tsc(); } -static u64 notrace read_hv_sched_clock_tsc(void) +static u64 noinstr read_hv_sched_clock_tsc(void) { return (read_hv_clock_tsc() - hv_sched_clock_offset) * (NSEC_PER_SEC / HV_CLOCK_HZ); @@ -466,22 +480,12 @@ static struct clocksource hyperv_cs_tsc #endif }; -static u64 notrace read_hv_clock_msr(void) -{ - /* - * Read the partition counter to get the current tick count. This count - * is set to 0 when the partition is created and is incremented in - * 100 nanosecond units. - */ - return hv_get_register(HV_REGISTER_TIME_REF_COUNT); -} - static u64 notrace read_hv_clock_msr_cs(struct clocksource *arg) { return read_hv_clock_msr(); } -static u64 notrace read_hv_sched_clock_msr(void) +static u64 noinstr read_hv_sched_clock_msr(void) { return (read_hv_clock_msr() - hv_sched_clock_offset) * (NSEC_PER_SEC / HV_CLOCK_HZ);