s390/sthyi: add s390_sthyi system call

Add a syscall of s390_sthyi to implement STHYI instruction in LPAR
which reuses the implementation for KVM by Janosch Frank -
commit 95ca2cb57985 ("KVM: s390: Add sthyi emulation").

STHYI(Store Hypervisor Information) is an emulated z/VM instruction that
provides a guest with basic information about the layers it is running
on. This includes information about the cpu configuration of both the
machine and the lpar, as well as their names, machine model and
machine type. This information enables an application to determine the
maximum capacity of CPs and IFLs available to software.

For the arguments of s390_sthyi, code shall be 0 and flags is reserved for
future use, info is the output argument to store the required hypervisor
info.

Signed-off-by: QingFeng Hao <haoqf@linux.vnet.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 32 insertions, 1 deletions

diff --git a/arch/s390/kernel/sthyi.c b/arch/s390/kernel/sthyi.c
index 27e3c3d87379..12981e197f01 100644
--- a/arch/s390/kernel/sthyi.c
+++ b/arch/s390/kernel/sthyi.c
@@ -11,13 +11,16 @@
 #include <linux/errno.h>
 #include <linux/pagemap.h>
 #include <linux/vmalloc.h>
-
+#include <linux/syscalls.h>
+#include <linux/mutex.h>
 #include <asm/asm-offsets.h>
 #include <asm/sclp.h>
 #include <asm/diag.h>
 #include <asm/sysinfo.h>
 #include <asm/ebcdic.h>
 #include <asm/facility.h>
+#include <asm/sthyi.h>
+#include "entry.h"
 
 #define DED_WEIGHT 0xffff
 /*
@@ -484,3 +487,31 @@ out:
 	return r;
 }
 EXPORT_SYMBOL_GPL(sthyi_fill);
+
+SYSCALL_DEFINE4(s390_sthyi, unsigned long, function_code, void __user *, buffer,
+		u64 __user *, return_code, unsigned long, flags)
+{
+	u64 sthyi_rc;
+	void *info;
+	int r;
+
+	if (flags)
+		return -EINVAL;
+	if (function_code != STHYI_FC_CP_IFL_CAP)
+		return -EOPNOTSUPP;
+	info = (void *)get_zeroed_page(GFP_KERNEL);
+	if (!info)
+		return -ENOMEM;
+	r = sthyi_fill(info, &sthyi_rc);
+	if (r < 0)
+		goto out;
+	if (return_code && put_user(sthyi_rc, return_code)) {
+		r = -EFAULT;
+		goto out;
+	}
+	if (copy_to_user(buffer, info, PAGE_SIZE))
+		r = -EFAULT;
+out:
+	free_page((unsigned long)info);
+	return r;
+}