From patchwork Thu Dec 14 02:47:25 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vineeth Remanan Pillai X-Patchwork-Id: 13492227 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bitbyteword.org header.i=@bitbyteword.org header.b="tTwcoFrp" Received: from mail-qt1-x830.google.com (mail-qt1-x830.google.com [IPv6:2607:f8b0:4864:20::830]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D310E19A for ; Wed, 13 Dec 2023 18:47:45 -0800 (PST) Received: by mail-qt1-x830.google.com with SMTP id d75a77b69052e-4258026a9fdso46759801cf.0 for ; Wed, 13 Dec 2023 18:47:45 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bitbyteword.org; s=google; t=1702522064; x=1703126864; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=MJ8V9wpZFRMaxTJ2Yr+JKkom97NUFELsE8HKkLVd89U=; b=tTwcoFrpm1z648NnqZPTYvJRG8qRAP6HhEhissBvfO3WICzlER+W4Tt/oI7kmMIP9f cuwJw6erApazvVuJOsmICilQm5tVsJlbPvoBAQY+jE8fhvJ9EEt+aZap7P6j2KrttjT8 ajUUve1LCghnI3HfHmKzTePg0y6NqTof15pSkJUrVGJfAwkHMmKPcC0ans+73KGvpcm6 +vIekWNczLtj8PFttljYj4NeVH0bB9j61SwGzwiZr3MnRn4KSJKHnf/9zLNnMWCea1H6 W5PDTA315RGU9qFRrhFMJ2R7vZiE4BPt4hvi2DwRLOND3Pwhozz5zAjH0glcKaUO+CQn 3JpQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1702522064; x=1703126864; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=MJ8V9wpZFRMaxTJ2Yr+JKkom97NUFELsE8HKkLVd89U=; b=qZOLXE1J2cdHQFspWg5ttzBc2A/jb+l2wK1qJHMvXWL8wEHsKYL1FL08JOr4pOovol kuh1FnZZwVbveiRFJJkVtV+bMw5vw7TR6PIF1YIAgDDYd4TuwD0SxbgwwKMNGNrfNOai YKESeNx5795wlQgAyDaSYRbWEpxUueSnJ82jYmZsQMjRfYIfr2blN+fC4WRXBufORv9k zxqH3jf1vLsMP4CagXvetq8bCq2Yjqxnqg+kRwC48q6vVziHbkaS1P6XfEZXSjCpcZRm rNSUgXxk3AIpCCFzdR1MVmcgV8k8cKWGm2XQCjHBN/aOQVicv11p+/GNKUCQ3ZGe0Imv 2awQ== X-Gm-Message-State: AOJu0YwEBHEG5qaUVVGOGCRfDVdL6B6mNqkRbw76MLHog+CLh9Hf1r4h NC+ECKHVL8+HvH0In1Um/LzEEA== X-Google-Smtp-Source: AGHT+IHCsSa54wlj5dnr98DogOBhKgfMGGbDmmsgR6hVaIJ/We5ltJAIKpR8uR1tHmUAsiuMmCDtIg== X-Received: by 2002:a05:622a:251:b0:418:1088:7d69 with SMTP id c17-20020a05622a025100b0041810887d69mr12636997qtx.18.1702522064725; Wed, 13 Dec 2023 18:47:44 -0800 (PST) Received: from vinp3lin.lan (c-73-143-21-186.hsd1.vt.comcast.net. [73.143.21.186]) by smtp.gmail.com with ESMTPSA id fh3-20020a05622a588300b00425b356b919sm4240208qtb.55.2023.12.13.18.47.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 13 Dec 2023 18:47:44 -0800 (PST) From: "Vineeth Pillai (Google)" To: Ben Segall , Borislav Petkov , Daniel Bristot de Oliveira , Dave Hansen , Dietmar Eggemann , "H . Peter Anvin" , Ingo Molnar , Juri Lelli , Mel Gorman , Paolo Bonzini , Andy Lutomirski , Peter Zijlstra , Sean Christopherson , Steven Rostedt , Thomas Gleixner , Valentin Schneider , Vincent Guittot , Vitaly Kuznetsov , Wanpeng Li Cc: "Vineeth Pillai (Google)" , Suleiman Souhlal , Masami Hiramatsu , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org, Joel Fernandes Subject: [RFC PATCH 8/8] irq: boost/unboost in irq/nmi entry/exit and softirq Date: Wed, 13 Dec 2023 21:47:25 -0500 Message-ID: <20231214024727.3503870-9-vineeth@bitbyteword.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20231214024727.3503870-1-vineeth@bitbyteword.org> References: <20231214024727.3503870-1-vineeth@bitbyteword.org> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 The host proactively boosts the VCPU threads during irq/nmi injection. However, the host is unaware of posted interrupts, and therefore, the guest should request a boost if it has not already been boosted. Similarly, guest should request an unboost on irq/nmi/softirq exit if the vcpu doesn't need the boost any more. Co-developed-by: Joel Fernandes (Google) Signed-off-by: Joel Fernandes (Google) Signed-off-by: Vineeth Pillai (Google) --- kernel/entry/common.c | 30 ++++++++++++++++++++++++++++++ kernel/softirq.c | 11 +++++++++++ 2 files changed, 41 insertions(+) diff --git a/kernel/entry/common.c b/kernel/entry/common.c index fae56faac0b0..c69912b71725 100644 --- a/kernel/entry/common.c +++ b/kernel/entry/common.c @@ -327,6 +327,13 @@ noinstr irqentry_state_t irqentry_enter(struct pt_regs *regs) .exit_rcu = false, }; +#ifdef CONFIG_PARAVIRT_SCHED + instrumentation_begin(); + if (pv_sched_enabled()) + pv_sched_boost_vcpu_lazy(); + instrumentation_end(); +#endif + if (user_mode(regs)) { irqentry_enter_from_user_mode(regs); return ret; @@ -452,6 +459,18 @@ noinstr void irqentry_exit(struct pt_regs *regs, irqentry_state_t state) if (state.exit_rcu) ct_irq_exit(); } + +#ifdef CONFIG_PARAVIRT_SCHED + instrumentation_begin(); + /* + * On irq exit, request a deboost from hypervisor if no softirq pending + * and current task is not RT and !need_resched. + */ + if (pv_sched_enabled() && !local_softirq_pending() && + !need_resched() && !task_is_realtime(current)) + pv_sched_unboost_vcpu(); + instrumentation_end(); +#endif } irqentry_state_t noinstr irqentry_nmi_enter(struct pt_regs *regs) @@ -469,6 +488,11 @@ irqentry_state_t noinstr irqentry_nmi_enter(struct pt_regs *regs) kmsan_unpoison_entry_regs(regs); trace_hardirqs_off_finish(); ftrace_nmi_enter(); + +#ifdef CONFIG_PARAVIRT_SCHED + if (pv_sched_enabled()) + pv_sched_boost_vcpu_lazy(); +#endif instrumentation_end(); return irq_state; @@ -482,6 +506,12 @@ void noinstr irqentry_nmi_exit(struct pt_regs *regs, irqentry_state_t irq_state) trace_hardirqs_on_prepare(); lockdep_hardirqs_on_prepare(); } + +#ifdef CONFIG_PARAVIRT_SCHED + if (pv_sched_enabled() && !in_hardirq() && !local_softirq_pending() && + !need_resched() && !task_is_realtime(current)) + pv_sched_unboost_vcpu(); +#endif instrumentation_end(); ct_nmi_exit(); diff --git a/kernel/softirq.c b/kernel/softirq.c index 807b34ccd797..90a127615e16 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -530,6 +530,11 @@ asmlinkage __visible void __softirq_entry __do_softirq(void) in_hardirq = lockdep_softirq_start(); account_softirq_enter(current); +#ifdef CONFIG_PARAVIRT_SCHED + if (pv_sched_enabled()) + pv_sched_boost_vcpu_lazy(); +#endif + restart: /* Reset the pending bitmask before enabling irqs */ set_softirq_pending(0); @@ -577,6 +582,12 @@ asmlinkage __visible void __softirq_entry __do_softirq(void) wakeup_softirqd(); } +#ifdef CONFIG_PARAVIRT_SCHED + if (pv_sched_enabled() && !need_resched() && + !task_is_realtime(current)) + pv_sched_unboost_vcpu(); +#endif + account_softirq_exit(current); lockdep_softirq_end(in_hardirq); softirq_handle_end();