[PATCH v2 1/1] s390: ipl: fix physical-virtual confusion for diag308

[Nico Boehr <nrb@linux.ibm.com>]

Diag 308 subcodes expect a physical address as their parameter.

This currently is not a bug, but in the future physical and virtual
addresses might differ.

Fix the confusion by doing a virtual-to-physical conversion in the
exported diag308() and leave the assembly wrapper __diag308() alone.

Note that several callers pass NULL as addr, this is _currently_ fine since
virt_to_phys(0) == 0. But in the future, lowcore addresses might no
longer be special, so make sure we pass 0 to hardware in case addr is
NULL.

Suggested-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
---
 arch/s390/kernel/ipl.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/s390/kernel/ipl.c b/arch/s390/kernel/ipl.c
index 5f0f5c86963a..d8b8a87626f7 100644
--- a/arch/s390/kernel/ipl.c
+++ b/arch/s390/kernel/ipl.c
@@ -176,7 +176,7 @@ static bool reipl_fcp_clear;
 static bool reipl_ccw_clear;
 static bool reipl_eckd_clear;
 
-static inline int __diag308(unsigned long subcode, void *addr)
+static inline int __diag308(unsigned long subcode, u64 addr)
 {
 	union register_pair r1;
 
@@ -195,7 +195,7 @@ static inline int __diag308(unsigned long subcode, void *addr)
 int diag308(unsigned long subcode, void *addr)
 {
 	diag_stat_inc(DIAG_STAT_X308);
-	return __diag308(subcode, addr);
+	return __diag308(subcode, addr ? virt_to_phys(addr) : 0);
 }
 EXPORT_SYMBOL_GPL(diag308);
 
-- 
2.39.1