powerpc/64: Only WARN if __pa()/__va() called with bad addresses

We added checks to __pa() / __va() to ensure they're only called with
appropriate addresses. But using BUG_ON() is too strong, it means
virt_addr_valid() will BUG when DEBUG_VIRTUAL is enabled.

Instead switch them to warnings, arm64 does the same.

Fixes: 4dd7554 ("powerpc/64: Add VIRTUAL_BUG_ON checks for __va and __pa addresses")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220406145802.538416-5-mpe@ellerman.id.au

arch/powerpc/include/asm/page.h

@@ -216,20 +216,23 @@ static inline bool pfn_valid(unsigned long pfn)
 #define __pa(x) ((phys_addr_t)(unsigned long)(x) - VIRT_PHYS_OFFSET)
 #else
 #ifdef CONFIG_PPC64
+
+#define VIRTUAL_WARN_ON(x)	WARN_ON(IS_ENABLED(CONFIG_DEBUG_VIRTUAL) && (x))
+
 /*
  * gcc miscompiles (unsigned long)(&static_var) - PAGE_OFFSET
  * with -mcmodel=medium, so we use & and | instead of - and + on 64-bit.
  * This also results in better code generation.
  */
 #define __va(x)								\
 ({									\
-	VIRTUAL_BUG_ON((unsigned long)(x) >= PAGE_OFFSET);		\
+	VIRTUAL_WARN_ON((unsigned long)(x) >= PAGE_OFFSET);		\
 	(void *)(unsigned long)((phys_addr_t)(x) | PAGE_OFFSET);	\
 })
 
 #define __pa(x)								\
 ({									\
-	VIRTUAL_BUG_ON((unsigned long)(x) < PAGE_OFFSET);		\
+	VIRTUAL_WARN_ON((unsigned long)(x) < PAGE_OFFSET);		\
 	(unsigned long)(x) & 0x0fffffffffffffffUL;			\
 })