Re: [PATCH v3 5/6] powerpc/pseries: implement paravirt qspinlocks for SPLPAR

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 7/9/20 6:53 AM, Michael Ellerman wrote:
Nicholas Piggin <npiggin@xxxxxxxxx> writes:

Signed-off-by: Nicholas Piggin <npiggin@xxxxxxxxx>
---
  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?

I am OK with adding the #ifdef around queued_spin_lock().

Acked-by: Waiman Long <longman@xxxxxxxxxx>

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?

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?
The PV qspinlock implementation is not that generic at the moment. Even though native qspinlock is used by a number of archs, PV qspinlock is only currently used in x86. This is certainly an area that needs improvement.
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.

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

We don't really need to do a pv_spinlocks_init() if pv_kick() isn't supported.

Cheers,
Longman




[Index of Archives]     [Linux Kernel]     [Kernel Newbies]     [x86 Platform Driver]     [Netdev]     [Linux Wireless]     [Netfilter]     [Bugtraq]     [Linux Filesystems]     [Yosemite Discussion]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Samba]     [Device Mapper]

  Powered by Linux