[PATCH/RFC 3/9] s390 guest detection

Carsten Otte
2007-05-11T17:35:55Z

From: Christian Borntraeger <cborntra-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org>

This patch adds functionality to detect if the kernel runs under an s390host
hypervisor. A macro MACHINE_IS_GUEST is exported for device drivers. This
allows drivers to skip device detection if the systems runs non-virtualized.

Signed-off-by: Christian Borntraeger <cborntra-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org>
Signed-off-by: Carsten Otte <cotte-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org>

---
arch/s390/kernel/early.c | 4 ++++
arch/s390/kernel/setup.c | 9 ++++++---
include/asm-s390/setup.h | 1 +
3 files changed, 11 insertions(+), 3 deletions(-)

Index: linux-2.6.21/arch/s390/kernel/setup.c
===================================================================
--- linux-2.6.21.orig/arch/s390/kernel/setup.c
+++ linux-2.6.21/arch/s390/kernel/setup.c
@@ -744,9 +744,12 @@ setup_arch(char **cmdline_p)
"This machine has an IEEE fpu\n" :
"This machine has no IEEE fpu\n");
#else /* CONFIG_64BIT */
- printk((MACHINE_IS_VM) ?
- "We are running under VM (64 bit mode)\n" :
- "We are running native (64 bit mode)\n");
+ if (MACHINE_IS_VM)
+ printk("We are running under VM (64 bit mode)\n");
+ else if (MACHINE_IS_GUEST)
+ printk("We are running on a non z/VM host\n");
+ else
+ printk("We are running native (64 bit mode)\n");
#endif /* CONFIG_64BIT */

/* Save unparsed command line copy for /proc/cmdline */
Index: linux-2.6.21/include/asm-s390/setup.h
===================================================================
--- linux-2.6.21.orig/include/asm-s390/setup.h
+++ linux-2.6.21/include/asm-s390/setup.h
@@ -61,6 +61,7 @@ extern unsigned long machine_flags;
#define MACHINE_IS_VM (machine_flags & 1)
#define MACHINE_IS_P390 (machine_flags & 4)
#define MACHINE_HAS_MVPG (machine_flags & 16)
+#define MACHINE_IS_GUEST (machine_flags & 64)
#define MACHINE_HAS_IDTE (machine_flags & 128)
#define MACHINE_HAS_DIAG9C (machine_flags & 256)

Index: linux-2.6.21/arch/s390/kernel/early.c
===================================================================
--- linux-2.6.21.orig/arch/s390/kernel/early.c
+++ linux-2.6.21/arch/s390/kernel/early.c
@@ -139,6 +139,10 @@ static noinline __init void detect_machi
/* Running on a P/390 ? */
if (cpuinfo->cpu_id.machine == 0x7490)
machine_flags |= 4;
+
+ /* Running under a host ? */
+ if (cpuinfo->cpu_id.version == 0xfe)
+ machine_flags |= 64;
}

#ifdef CONFIG_64BIT