Merge git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-lguest

# This creates the demonstration utility "lguest" which runs a Linux guest.

# For those people that have a separate object dir, look there for .config

KBUILD_OUTPUT := ../..

ifdef O

  ifeq ("$(origin O)", "command line")

    KBUILD_OUTPUT := $(O)

  endif

endif

# We rely on CONFIG_PAGE_OFFSET to know where to put lguest binary.

include $(KBUILD_OUTPUT)/.config

LGUEST_GUEST_TOP := ($(CONFIG_PAGE_OFFSET) - 0x08000000)

CFLAGS:=-Wall -Wmissing-declarations -Wmissing-prototypes -O3 -Wl,-T,lguest.lds

CFLAGS:=-Wall -Wmissing-declarations -Wmissing-prototypes -O3 -I../../include

LDLIBS:=-lz

# Removing this works for some versions of ld.so (eg. Ubuntu Feisty) and

# not others (eg. FC7).

LDFLAGS+=-static

all: lguest.lds lguest

# The linker script on x86 is so complex the only way of creating one

# which will link our binary in the right place is to mangle the

# default one.

lguest.lds:

	$(LD) --verbose | awk '/^==========/ { PRINT=1; next; } /SIZEOF_HEADERS/ { gsub(/0x[0-9A-F]*/, "$(LGUEST_GUEST_TOP)") } { if (PRINT) print $$0; }' > $@

all: lguest

clean:

	rm -f lguest.lds lguest

	rm -f lguest

Linux developers and users to experiment with virtualization with the

minimum of complexity.  Nonetheless, it should have sufficient

features to make it useful for specific tasks, and, of course, you are

encouraged to fork and enhance it.

encouraged to fork and enhance it (see drivers/lguest/README).

Features:

Running Lguest:

- Lguest runs the same kernel as guest and host.  You can configure

  them differently, but usually it's easiest not to.

- The easiest way to run lguest is to use same kernel as guest and host.

  You can configure them differently, but usually it's easiest not to.

  You will need to configure your kernel with the following options:

  CONFIG_HIGHMEM64G=n ("High Memory Support" "64GB")[1]

  CONFIG_TUN=y/m ("Universal TUN/TAP device driver support")

  CONFIG_EXPERIMENTAL=y ("Prompt for development and/or incomplete code/drivers")

  CONFIG_PARAVIRT=y ("Paravirtualization support (EXPERIMENTAL)")

  CONFIG_LGUEST=y/m ("Linux hypervisor example code")

  and I recommend:

  CONFIG_HZ=100 ("Timer frequency")[2]

  "General setup":

     "Prompt for development and/or incomplete code/drivers" = Y

        (CONFIG_EXPERIMENTAL=y)

  "Processor type and features":

     "Paravirtualized guest support" = Y

        "Lguest guest support" = Y

     "High Memory Support" = off/4GB

     "Alignment value to which kernel should be aligned" = 0x100000

        (CONFIG_PARAVIRT=y, CONFIG_LGUEST_GUEST=y, CONFIG_HIGHMEM64G=n and

         CONFIG_PHYSICAL_ALIGN=0x100000)

  "Device Drivers":

     "Network device support"

        "Universal TUN/TAP device driver support" = M/Y

           (CONFIG_TUN=m)

     "Virtualization"

        "Linux hypervisor example code" = M/Y

           (CONFIG_LGUEST=m)

- A tool called "lguest" is available in this directory: type "make"

  to build it.  If you didn't build your kernel in-tree, use "make

	  dd if=/dev/zero of=rootfile bs=1M count=2048

	  qemu -cdrom image.iso -hda rootfile -net user -net nic -boot d

  Make sure that you install a getty on /dev/hvc0 if you want to log in on the

  console!

- "modprobe lg" if you built it as a module.

- Run an lguest as root:

      Documentation/lguest/lguest 64m vmlinux --tunnet=192.168.19.1 --block=rootfile root=/dev/lgba

      Documentation/lguest/lguest 64 vmlinux --tunnet=192.168.19.1 --block=rootfile root=/dev/vda

   Explanation:

    64m: the amount of memory to use.

    64: the amount of memory to use, in MB.

    vmlinux: the kernel image found in the top of your build directory.  You

       can also use a standard bzImage.

    --tunnet=192.168.19.1: configures a "tap" device for networking with this

       IP address.

    --block=rootfile: a file or block device which becomes /dev/lgba

    --block=rootfile: a file or block device which becomes /dev/vda

       inside the guest.

    root=/dev/lgba: this (and anything else on the command line) are

    root=/dev/vda: this (and anything else on the command line) are

       kernel boot parameters.

- Configuring networking.  I usually have the host masquerade, using

  "--sharenet=<filename>": any two guests using the same file are on

  the same network.  This file is created if it does not exist.

Lguest I/O model:

Lguest uses a simplified DMA model plus shared memory for I/O.  Guests

can communicate with each other if they share underlying memory

(usually by the lguest program mmaping the same file), but they can

use any non-shared memory to communicate with the lguest process.

Guests can register DMA buffers at any key (must be a valid physical

address) using the LHCALL_BIND_DMA(key, dmabufs, num<<8|irq)

hypercall.  "dmabufs" is the physical address of an array of "num"

"struct lguest_dma": each contains a used_len, and an array of

physical addresses and lengths.  When a transfer occurs, the

"used_len" field of one of the buffers which has used_len 0 will be

set to the length transferred and the irq will fire.

There is a helpful mailing list at http://ozlabs.org/mailman/listinfo/lguest

Using an irq value of 0 unbinds the dma buffers.

To send DMA, the LHCALL_SEND_DMA(key, dma_physaddr) hypercall is used,

and the bytes used is written to the used_len field.  This can be 0 if

noone else has bound a DMA buffer to that key or some other error.

DMA buffers bound by the same guest are ignored.

Cheers!

Good luck!

Rusty Russell rusty@rustcorp.com.au.

[1] These are on various places on the TODO list, waiting for you to

    get annoyed enough at the limitation to fix it.

[2] Lguest is not yet tickless when idle.  See [1].

	  If in doubt, say "Y".

config PARAVIRT

	bool "Paravirtualization support (EXPERIMENTAL)"

	depends on EXPERIMENTAL

	bool

	depends on !(X86_VISWS || X86_VOYAGER)

	help

	  Paravirtualization is a way of running multiple instances of

	  Linux on the same machine, under a hypervisor.  This option

	  changes the kernel so it can modify itself when it is run

	  under a hypervisor, improving performance significantly.

	  However, when run without a hypervisor the kernel is

	  theoretically slower.  If in doubt, say N.

	  This changes the kernel so it can modify itself when it is run

	  under a hypervisor, potentially improving performance significantly

	  over full virtualization.  However, when run without a hypervisor

	  the kernel is theoretically slower and slightly larger.

menuconfig PARAVIRT_GUEST

	bool "Paravirtualized guest support"

	help

	  Say Y here to get to see options related to running Linux under

	  various hypervisors.  This option alone does not add any kernel code.

	  If you say N, all options in this submenu will be skipped and disabled.

if PARAVIRT_GUEST

source "arch/x86/xen/Kconfig"

config VMI

	bool "VMI Paravirt-ops support"

	depends on PARAVIRT

	bool "VMI Guest support"

	select PARAVIRT

	depends on !(X86_VISWS || X86_VOYAGER)

	help

	  VMI provides a paravirtualized interface to the VMware ESX server

	  (it could be used by other hypervisors in theory too, but is not

	  at the moment), by linking the kernel to a GPL-ed ROM module

	  provided by the hypervisor.

source "arch/x86/lguest/Kconfig"

endif

config ACPI_SRAT

	bool

	default y

# Xen paravirtualization support

core-$(CONFIG_XEN)		+= arch/x86/xen/

# lguest paravirtualization support

core-$(CONFIG_LGUEST_GUEST)	+= arch/x86/lguest/

# default subarch .h files

mflags-y += -Iinclude/asm-x86/mach-default