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authorRusty Russell <rusty@rustcorp.com.au>2007-10-22 11:24:21 +1000
committerRusty Russell <rusty@rustcorp.com.au>2007-10-23 15:49:56 +1000
commit19f1537b7b8a9a82665db3ad8210a9d954d13acd (patch)
tree793c1f8763350012caa521a55c5778b1c633b7e5 /arch
parent15045275c32bf6d15d32c2eca8157be9c0ba6e45 (diff)
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Lguest support for Virtio
This makes lguest able to use the virtio devices. We change the device descriptor page from a simple array to a variable length "type, config_len, status, config data..." format, and implement virtio_config_ops to read from that config data. We use the virtio ring implementation for an efficient Guest <-> Host virtqueue mechanism, and the new LHCALL_NOTIFY hypercall to kick the host when it changes. We also use LHCALL_NOTIFY on kernel addresses for very very early console output. We could have another hypercall, but this hack works quite well. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/lguest/Kconfig5
-rw-r--r--arch/x86/lguest/boot.c21
2 files changed, 26 insertions, 0 deletions
diff --git a/arch/x86/lguest/Kconfig b/arch/x86/lguest/Kconfig
index 44dccfd845f..c4dffbeea5e 100644
--- a/arch/x86/lguest/Kconfig
+++ b/arch/x86/lguest/Kconfig
@@ -2,8 +2,13 @@ config LGUEST_GUEST
bool "Lguest guest support"
select PARAVIRT
depends on !X86_PAE
+ select VIRTIO
select VIRTIO_RING
+ select VIRTIO_CONSOLE
help
Lguest is a tiny in-kernel hypervisor. Selecting this will
allow your kernel to boot under lguest. This option will increase
your kernel size by about 6k. If in doubt, say N.
+
+ If you say Y here, make sure you say Y (or M) to the virtio block
+ and net drivers which lguest needs.
diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c
index 959aeebb02f..495e46a1f11 100644
--- a/arch/x86/lguest/boot.c
+++ b/arch/x86/lguest/boot.c
@@ -55,6 +55,7 @@
#include <linux/clockchips.h>
#include <linux/lguest.h>
#include <linux/lguest_launcher.h>
+#include <linux/virtio_console.h>
#include <asm/paravirt.h>
#include <asm/param.h>
#include <asm/page.h>
@@ -849,6 +850,23 @@ static __init char *lguest_memory_setup(void)
return "LGUEST";
}
+/* Before virtqueues are set up, we use LHCALL_NOTIFY on normal memory to
+ * produce console output. */
+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);
+ hcall(LHCALL_NOTIFY, __pa(scratch), 0, 0);
+
+ /* This routine returns the number of bytes actually written. */
+ return len;
+}
+
/*G:050
* Patching (Powerfully Placating Performance Pedants)
*
@@ -1048,6 +1066,9 @@ __init void lguest_init(void *boot)
* adapted for lguest's use. */
add_preferred_console("hvc", 0, NULL);
+ /* Register our very early console. */
+ virtio_cons_early_init(early_put_chars);
+
/* Last of all, we set the power management poweroff hook to point to
* the Guest routine to power off. */
pm_power_off = lguest_power_off;