From: Christian Borntraeger <[EMAIL PROTECTED]>
From: Carsten Otte <[EMAIL PROTECTED]>

This patch adds functionality to detect if the kernel runs under the KVM
hypervisor. A macro MACHINE_IS_KVM is exported for device drivers. This
allows drivers to skip device detection if the systems runs non-virtualized.
We also define a preferred console to avoid having the ttyS0, which is a line
mode only console.

Signed-off-by: Christian Borntraeger <[EMAIL PROTECTED]>
Acked-by: Martin Schwidefsky <[EMAIL PROTECTED]>
Signed-off-by: Carsten Otte <[EMAIL PROTECTED]>
---
 arch/s390/Kconfig        |    7 +++++++
 arch/s390/kernel/early.c |    4 ++++
 arch/s390/kernel/setup.c |   10 +++++++---
 include/asm-s390/setup.h |    1 +
 4 files changed, 19 insertions(+), 3 deletions(-)

Index: kvm/arch/s390/Kconfig
===================================================================
--- kvm.orig/arch/s390/Kconfig
+++ kvm/arch/s390/Kconfig
@@ -533,6 +533,13 @@ config ZFCPDUMP
          Select this option if you want to build an zfcpdump enabled kernel.
          Refer to <file:Documentation/s390/zfcpdump.txt> for more details on 
this.
 
+config S390_GUEST
+bool "s390 guest support (EXPERIMENTAL)"
+       depends on 64BIT && EXPERIMENTAL
+       select VIRTIO
+       select VIRTIO_RING
+       help
+         Select this option if you want to run the kernel under s390 linux
 endmenu
 
 source "net/Kconfig"
Index: kvm/arch/s390/kernel/early.c
===================================================================
--- kvm.orig/arch/s390/kernel/early.c
+++ kvm/arch/s390/kernel/early.c
@@ -143,6 +143,10 @@ static noinline __init void detect_machi
        /* Running on a P/390 ? */
        if (cpuinfo->cpu_id.machine == 0x7490)
                machine_flags |= 4;
+
+       /* Running under KVM ? */
+       if (cpuinfo->cpu_id.version == 0xfe)
+               machine_flags |= 64;
 }
 
 #ifdef CONFIG_64BIT
Index: kvm/arch/s390/kernel/setup.c
===================================================================
--- kvm.orig/arch/s390/kernel/setup.c
+++ kvm/arch/s390/kernel/setup.c
@@ -793,9 +793,13 @@ 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_KVM) {
+               printk("We are running under KVM (64 bit mode)\n");
+               add_preferred_console("ttyS", 1, NULL);
+       } else
+               printk("We are running native (64 bit mode)\n");
 #endif /* CONFIG_64BIT */
 
        /* Save unparsed command line copy for /proc/cmdline */
Index: kvm/include/asm-s390/setup.h
===================================================================
--- kvm.orig/include/asm-s390/setup.h
+++ kvm/include/asm-s390/setup.h
@@ -62,6 +62,7 @@ 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_KVM         (machine_flags & 64)
 #define MACHINE_HAS_IDTE       (machine_flags & 128)
 #define MACHINE_HAS_DIAG9C     (machine_flags & 256)
 



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