Subject: [PATCH v5 07/10] powerpc/book3s/pmem: Add WARN_ONCE to catch the wrong usage of pmem flush functions.

From: "Aneesh Kumar K.V" <[email-masked]>
Date: Wed, 10 Jun 2020 11:53:40 +0530

We only support persistent memory on P8 and above. This is enforced by the
firmware and further checked on virtualzied platform during platform init.
Add WARN_ONCE in pmem flush routines to catch the wrong usage of these.

Signed-off-by: Aneesh Kumar K.V <[email-masked]>
---
 arch/powerpc/include/asm/cacheflush.h | 2 ++
 arch/powerpc/lib/pmem.c               | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/arch/powerpc/include/asm/cacheflush.h b/arch/powerpc/include/asm/cacheflush.h
index bb56a49c9a66..6dad92bd4be3 100644
--- a/arch/powerpc/include/asm/cacheflush.h
+++ b/arch/powerpc/include/asm/cacheflush.h
@@ -126,6 +126,8 @@ static inline void  arch_pmem_flush_barrier(void)
 {
 	if (cpu_has_feature(CPU_FTR_ARCH_207S))
 		asm volatile(PPC_PHWSYNC ::: "memory");
+	else
+		WARN_ONCE(1, "Using pmem flush on older hardware.");
 }
 #endif /* __KERNEL__ */
 
diff --git a/arch/powerpc/lib/pmem.c b/arch/powerpc/lib/pmem.c
index 21210fa676e5..f40bd908d28d 100644
--- a/arch/powerpc/lib/pmem.c
+++ b/arch/powerpc/lib/pmem.c
@@ -37,12 +37,14 @@ static inline void clean_pmem_range(unsigned long start, unsigned long stop)
 {
 	if (cpu_has_feature(CPU_FTR_ARCH_207S))
 		return __clean_pmem_range(start, stop);
+	WARN_ONCE(1, "Using pmem flush on older hardware.");
 }
 
 static inline void flush_pmem_range(unsigned long start, unsigned long stop)
 {
 	if (cpu_has_feature(CPU_FTR_ARCH_207S))
 		return __flush_pmem_range(start, stop);
+	WARN_ONCE(1, "Using pmem flush on older hardware.");
 }
 
 /*
-- 
2.26.2