linux-kernel - [PATCHv2 3/4] arm64: do not use dummy vcpu_is

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Date:   Fri,  9 Jul 2021 13:37:12 +0900
From:   Sergey Senozhatsky <senozhatsky@...omium.org>
To:     Marc Zyngier <maz@...nel.org>, Will Deacon <will@...nel.org>
Cc:     Suleiman Souhlal <suleiman@...gle.com>,
        Joel Fernandes <joelaf@...gle.com>,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        linux-kernel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org,
        Sergey Senozhatsky <senozhatsky@...omium.org>
Subject: [PATCHv2 3/4] arm64: do not use dummy vcpu_is_preempted()

vcpu_is_preempted() now can represent the actual state of
the VCPU, so the scheduler can make better decisions when
it picks the idle CPU to enqueue a task on.

Signed-off-by: Sergey Senozhatsky <senozhatsky@...omium.org>
---
 arch/arm64/include/asm/spinlock.h | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/include/asm/spinlock.h b/arch/arm64/include/asm/spinlock.h
index 0525c0b089ed..1d579497e1b8 100644
--- a/arch/arm64/include/asm/spinlock.h
+++ b/arch/arm64/include/asm/spinlock.h
@@ -7,21 +7,23 @@
 
 #include <asm/qspinlock.h>
 #include <asm/qrwlock.h>
+#include <asm/paravirt.h>
 
 /* See include/linux/spinlock.h */
 #define smp_mb__after_spinlock()	smp_mb()
 
-/*
- * Changing this will break osq_lock() thanks to the call inside
- * smp_cond_load_relaxed().
- *
- * See:
- * https://lore.kernel.org/lkml/20200110100612.GC2827@hirez.programming.kicks-ass.net
- */
 #define vcpu_is_preempted vcpu_is_preempted
-static inline bool vcpu_is_preempted(int cpu)
+
+#ifdef CONFIG_PARAVIRT
+static inline bool vcpu_is_preempted(unsigned int cpu)
+{
+	return paravirt_vcpu_is_preempted(cpu);
+}
+#else
+static inline bool vcpu_is_preempted(unsigned int cpu)
 {
 	return false;
 }
+#endif /* CONFIG_PARAVIRT */
 
 #endif /* __ASM_SPINLOCK_H */
-- 
2.32.0.93.g670b81a890-goog