linux-kernel - [RESEND][patch V3 21/23] context_tracking: Make guest_enter/exit

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Date:   Fri, 20 Mar 2020 19:00:17 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     x86@...nel.org, Paul McKenney <paulmck@...nel.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        "Joel Fernandes (Google)" <joel@...lfernandes.org>,
        "Steven Rostedt (VMware)" <rostedt@...dmis.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Frederic Weisbecker <frederic@...nel.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Brian Gerst <brgerst@...il.com>,
        Juergen Gross <jgross@...e.com>,
        Alexandre Chartre <alexandre.chartre@...cle.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Paolo Bonzini <pbonzini@...hat.com>, kvm@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>
Subject: [RESEND][patch V3 21/23] context_tracking: Make
 guest_enter/exit_irqoff() .noinstr ready

Mark the functions __always_inline and add the annotations for the "safe"
calls into regular text sections where RCU is watching.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Tom Lendacky <thomas.lendacky@....com>
Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org
---
 include/linux/context_tracking.h |   21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

--- a/include/linux/context_tracking.h
+++ b/include/linux/context_tracking.h
@@ -101,12 +101,14 @@ static inline void context_tracking_init
 
 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
 /* must be called with irqs disabled */
-static inline void guest_enter_irqoff(void)
+static __always_inline void guest_enter_irqoff(void)
 {
+	instr_begin();
 	if (vtime_accounting_enabled_this_cpu())
 		vtime_guest_enter(current);
 	else
 		current->flags |= PF_VCPU;
+	instr_end();
 
 	if (context_tracking_enabled())
 		__context_tracking_enter(CONTEXT_GUEST);
@@ -118,39 +120,48 @@ static inline void guest_enter_irqoff(vo
 	 * one time slice). Lets treat guest mode as quiescent state, just like
 	 * we do with user-mode execution.
 	 */
-	if (!context_tracking_enabled_this_cpu())
+	if (!context_tracking_enabled_this_cpu()) {
+		instr_begin();
 		rcu_virt_note_context_switch(smp_processor_id());
+		instr_end();
+	}
 }
 
-static inline void guest_exit_irqoff(void)
+static __always_inline void guest_exit_irqoff(void)
 {
 	if (context_tracking_enabled())
 		__context_tracking_exit(CONTEXT_GUEST);
 
+	instr_begin();
 	if (vtime_accounting_enabled_this_cpu())
 		vtime_guest_exit(current);
 	else
 		current->flags &= ~PF_VCPU;
+	instr_end();
 }
 
 #else
-static inline void guest_enter_irqoff(void)
+static __always_inline void guest_enter_irqoff(void)
 {
 	/*
 	 * This is running in ioctl context so its safe
 	 * to assume that it's the stime pending cputime
 	 * to flush.
 	 */
+	instr_begin();
 	vtime_account_kernel(current);
 	current->flags |= PF_VCPU;
 	rcu_virt_note_context_switch(smp_processor_id());
+	instr_end();
 }
 
-static inline void guest_exit_irqoff(void)
+static __always_inline void guest_exit_irqoff(void)
 {
+	instr_begin();
 	/* Flush the guest cputime we spent on the guest */
 	vtime_account_kernel(current);
 	current->flags &= ~PF_VCPU;
+	instr_end();
 }
 #endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */