Re: [PATCH v3 5/6] powerpc/pseries: implement paravirt qspinlocks for SPLPAR
From: Michael Ellerman <mpe@ellerman.id.au>
Date: 2020-07-09 10:51:10
Also in:
linux-arch, lkml, virtualization
Subsystem:
linux for powerpc (32-bit and 64-bit), locking primitives, the rest · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Peter Zijlstra, Ingo Molnar, Will Deacon, Boqun Feng, Linus Torvalds
Nicholas Piggin [off-list ref] writes:
Signed-off-by: Nicholas Piggin <npiggin@gmail.com> --- arch/powerpc/include/asm/paravirt.h | 28 ++++++++ arch/powerpc/include/asm/qspinlock.h | 66 +++++++++++++++++++ arch/powerpc/include/asm/qspinlock_paravirt.h | 7 ++ arch/powerpc/platforms/pseries/Kconfig | 5 ++ arch/powerpc/platforms/pseries/setup.c | 6 +- include/asm-generic/qspinlock.h | 2 +
Another ack?
quoted hunk ↗ jump to hunk
diff --git a/arch/powerpc/include/asm/paravirt.h b/arch/powerpc/include/asm/paravirt.h index 7a8546660a63..f2d51f929cf5 100644 --- a/arch/powerpc/include/asm/paravirt.h +++ b/arch/powerpc/include/asm/paravirt.h@@ -45,6 +55,19 @@ static inline void yield_to_preempted(int cpu, u32 yield_count) { ___bad_yield_to_preempted(); /* This would be a bug */ } + +extern void ___bad_yield_to_any(void); +static inline void yield_to_any(void) +{ + ___bad_yield_to_any(); /* This would be a bug */ +}
Why do we do that rather than just not defining yield_to_any() at all and letting the build fail on that? There's a condition somewhere that we know will false at compile time and drop the call before linking?
quoted hunk ↗ jump to hunk
diff --git a/arch/powerpc/include/asm/qspinlock_paravirt.h b/arch/powerpc/include/asm/qspinlock_paravirt.h new file mode 100644 index 000000000000..750d1b5e0202 --- /dev/null +++ b/arch/powerpc/include/asm/qspinlock_paravirt.h@@ -0,0 +1,7 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +#ifndef __ASM_QSPINLOCK_PARAVIRT_H +#define __ASM_QSPINLOCK_PARAVIRT_H
_ASM_POWERPC_QSPINLOCK_PARAVIRT_H please.
+ +EXPORT_SYMBOL(__pv_queued_spin_unlock);
Why's that in a header? Should that (eventually) go with the generic implementation?
quoted hunk ↗ jump to hunk
diff --git a/arch/powerpc/platforms/pseries/Kconfig b/arch/powerpc/platforms/pseries/Kconfig index 24c18362e5ea..756e727b383f 100644 --- a/arch/powerpc/platforms/pseries/Kconfig +++ b/arch/powerpc/platforms/pseries/Kconfig@@ -25,9 +25,14 @@ config PPC_PSERIES select SWIOTLB default y +config PARAVIRT_SPINLOCKS + bool + default n
default n is the default.
quoted hunk ↗ jump to hunk
diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c index 2db8469e475f..747a203d9453 100644 --- a/arch/powerpc/platforms/pseries/setup.c +++ b/arch/powerpc/platforms/pseries/setup.c@@ -771,8 +771,12 @@ static void __init pSeries_setup_arch(void) if (firmware_has_feature(FW_FEATURE_LPAR)) { vpa_init(boot_cpuid); - if (lppaca_shared_proc(get_lppaca())) + if (lppaca_shared_proc(get_lppaca())) { static_branch_enable(&shared_processor); +#ifdef CONFIG_PARAVIRT_SPINLOCKS + pv_spinlocks_init(); +#endif + }
We could avoid the ifdef with this I think?
diff --git a/arch/powerpc/include/asm/spinlock.h b/arch/powerpc/include/asm/spinlock.h
index 434615f1d761..6ec72282888d 100644
--- a/arch/powerpc/include/asm/spinlock.h
+++ b/arch/powerpc/include/asm/spinlock.h@@ -10,5 +10,9 @@ #include <asm/simple_spinlock.h> #endif +#ifndef CONFIG_PARAVIRT_SPINLOCKS +static inline void pv_spinlocks_init(void) { } +#endif + #endif /* __KERNEL__ */ #endif /* __ASM_SPINLOCK_H */
cheers