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[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> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" 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 =3D false, }; =20 +#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, irqen= try_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 } =20 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(); =20 return irq_state; @@ -482,6 +506,12 @@ void noinstr irqentry_nmi_exit(struct pt_regs *regs, i= rqentry_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(); =20 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 =3D lockdep_softirq_start(); account_softirq_enter(current); =20 +#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(); } =20 +#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(); --=20 2.43.0