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s390: use virtio_console for KVM on s390
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This patch enables virtio_console as the default console on kvm for
s390. We currently use the same notify hack as lguest for early
console output. I will try to address this for lguest and s390 later.

Signed-off-by: Christian Borntraeger <[email protected]>
Signed-off-by: Rusty Russell <[email protected]>
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borntraeger authored and rustyrussell committed Jul 25, 2008
1 parent 7721c49 commit faeba83
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Showing 4 changed files with 34 additions and 1 deletion.
1 change: 1 addition & 0 deletions arch/s390/Kconfig
Original file line number Diff line number Diff line change
Expand Up @@ -565,6 +565,7 @@ bool "s390 guest support (EXPERIMENTAL)"
depends on 64BIT && EXPERIMENTAL
select VIRTIO
select VIRTIO_RING
select VIRTIO_CONSOLE
help
Select this option if you want to run the kernel under s390 linux
endmenu
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4 changes: 3 additions & 1 deletion arch/s390/kernel/setup.c
Original file line number Diff line number Diff line change
Expand Up @@ -54,6 +54,7 @@
#include <asm/sections.h>
#include <asm/ebcdic.h>
#include <asm/compat.h>
#include <asm/kvm_virtio.h>

long psw_kernel_bits = (PSW_BASE_BITS | PSW_MASK_DAT | PSW_ASC_PRIMARY |
PSW_MASK_MCHECK | PSW_DEFAULT_KEY);
Expand Down Expand Up @@ -766,7 +767,8 @@ setup_arch(char **cmdline_p)
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);
add_preferred_console("hvc", 0, NULL);
s390_virtio_console_init();
} else
printk("We are running native (64 bit mode)\n");
#endif /* CONFIG_64BIT */
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20 changes: 20 additions & 0 deletions drivers/s390/kvm/kvm_virtio.c
Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,7 @@
#include <linux/err.h>
#include <linux/virtio.h>
#include <linux/virtio_config.h>
#include <linux/virtio_console.h>
#include <linux/interrupt.h>
#include <linux/virtio_ring.h>
#include <linux/pfn.h>
Expand Down Expand Up @@ -333,6 +334,25 @@ static int __init kvm_devices_init(void)
return 0;
}

/* code for early console output with virtio_console */
static __init int early_put_chars(u32 vtermno, const char *buf, int count)
{
char scratch[17];
unsigned int len = count;

if (len > sizeof(scratch) - 1)
len = sizeof(scratch) - 1;
scratch[len] = '\0';
memcpy(scratch, buf, len);
kvm_hypercall1(KVM_S390_VIRTIO_NOTIFY, __pa(scratch));
return len;
}

void s390_virtio_console_init(void)
{
virtio_cons_early_init(early_put_chars);
}

/*
* We do this after core stuff, but before the drivers.
*/
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10 changes: 10 additions & 0 deletions include/asm-s390/kvm_virtio.h
Original file line number Diff line number Diff line change
Expand Up @@ -50,4 +50,14 @@ struct kvm_vqconfig {
#define KVM_S390_VIRTIO_RESET 1
#define KVM_S390_VIRTIO_SET_STATUS 2

#ifdef __KERNEL__
/* early virtio console setup */
#ifdef CONFIG_VIRTIO_CONSOLE
extern void s390_virtio_console_init(void);
#else
static inline void s390_virtio_console_init(void)
{
}
#endif /* CONFIG_VIRTIO_CONSOLE */
#endif /* __KERNEL__ */
#endif

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