kvmtool / kvmtool Goto Github PK

Stand-alone Native Linux KVM Tool repo

License: GNU General Public License v2.0

Makefile 1.95% C 97.35% Assembly 0.36% Shell 0.34%

kvmtool's Introduction

Native Linux KVM tool
=====================

kvmtool is a lightweight tool for hosting KVM guests. As a pure virtualization
tool it only supports guests using the same architecture, though it supports
running 32-bit guests on those 64-bit architectures that allow this.

From the original announcement email:
-------------------------------------------------------
The goal of this tool is to provide a clean, from-scratch, lightweight
KVM host tool implementation that can boot Linux guest images (just a
hobby, won't be big and professional like QEMU) with no BIOS
dependencies and with only the minimal amount of legacy device
emulation.

It's great as a learning tool if you want to get your feet wet in
virtualization land: it's only 5 KLOC of clean C code that can already
boot a guest Linux image.

Right now it can boot a Linux image and provide you output via a serial
console, over the host terminal, i.e. you can use it to boot a guest
Linux image in a terminal or over ssh and log into the guest without
much guest or host side setup work needed.
--------------------------

This is the stand-alone version which does not live inside a Linux
kernel tree.
1. To check it out, clone the main git repository:

  git clone git://git.kernel.org/pub/scm/linux/kernel/git/will/kvmtool.git

2. Compile the tool (for more elaborate instructions see INSTALL):

  cd kvmtool && make

3. Download a raw userspace image:

  wget http://wiki.qemu.org/download/linux-0.2.img.bz2 && bunzip2
linux-0.2.img.bz2

4. The guest kernel has to be built with the following configuration:

 - For the default console output:
	CONFIG_SERIAL_8250=y
	CONFIG_SERIAL_8250_CONSOLE=y

 - For running 32bit images on 64bit hosts:
	CONFIG_IA32_EMULATION=y

 - Proper FS options according to image FS (e.g. CONFIG_EXT2_FS, CONFIG_EXT4_FS).

 - For all virtio devices listed below:
	CONFIG_VIRTIO=y
	CONFIG_VIRTIO_RING=y
	CONFIG_VIRTIO_PCI=y

 - For virtio-blk devices (--disk, -d):
	CONFIG_VIRTIO_BLK=y

 - For virtio-net devices ([--network, -n] virtio):
	CONFIG_VIRTIO_NET=y

 - For virtio-9p devices (--virtio-9p):
	CONFIG_NET_9P=y
	CONFIG_NET_9P_VIRTIO=y
	CONFIG_9P_FS=y

 - For virtio-balloon device (--balloon):
	CONFIG_VIRTIO_BALLOON=y

 - For virtio-console device (--console virtio):
	CONFIG_VIRTIO_CONSOLE=y

 - For virtio-rng device (--rng):
	CONFIG_HW_RANDOM_VIRTIO=y

 - For vesa device (--sdl or --vnc):
	CONFIG_FB_VESA=y


5. And finally, launch the hypervisor:

  ./lkvm run --disk linux-0.2.img \
	    --kernel ../../arch/x86/boot/bzImage \
or

  sudo ./lkvm run --disk linux-0.2.img \
		 --kernel ../../arch/x86/boot/bzImage \
		 --network virtio

The tool has been written by Pekka Enberg, Cyrill Gorcunov, Asias He,
Sasha Levin and Prasad Joshi. Special thanks to Avi Kivity for his help
on KVM internals and Ingo Molnar for all-around support and encouragement!

See the following thread for original discussion for motivation of this
project:

http://thread.gmane.org/gmane.linux.kernel/962051/focus=962620

Another detailed example can be found in the lwn.net article:

http://lwn.net/Articles/658511/

Contributing
------------

Please send patches for kvmtool to [email protected], in the usual git
patch format, including "kvmtool" in the mail subject. "kvmtool" can be
added automatically by issuing the command

 git config format.subjectprefix "PATCH kvmtool"

in the git repository.

Maintainers
-----------

kvmtool is maintained by Will Deacon <[email protected]> and Julien Thierry
<[email protected]>.

kvmtool's People

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kvmtool's Issues

How to test riscv guest interrupt

Does RISC-V support guest interrupt pass-through, and how can MSI interrupts be directly sent to a guest?

KVM_CREATE_PIT2

Hello,

kvm.c<x86> reads:

 133 │ void kvm__arch_init(struct kvm *kvm, const char *hugetlbfs_path, u64 ram_size)                                         
 134 │ {                                                                                                                      
 135 │     struct kvm_pit_config pit_config = { .flags = 0, };                                                                
 136 │     int ret;                                                                                                           
 137 │                                                                                                                        
 138 │     ret = ioctl(kvm->vm_fd, KVM_SET_TSS_ADDR, 0xfffbd000);                                                             
 139 │     if (ret < 0)                                                                                                       
 140 │         die_perror("KVM_SET_TSS_ADDR ioctl");                                                                          
 141 │                                                                                                                        
 142 │     ret = ioctl(kvm->vm_fd, KVM_CREATE_PIT2, &pit_config);                                                             
 143 │     if (ret < 0)                                                                                                       
 144 │         die_perror("KVM_CREATE_PIT2 ioctl");                                                                           
 145 │                                                                                                                        
 146 │     if (ram_size < KVM_32BIT_GAP_START) {                                                                              
 147 │         kvm->ram_size = ram_size;                                                                                      
 148 │         kvm->ram_start = mmap_anon_or_hugetlbfs(kvm, hugetlbfs_path, ram_size);                                        
 149 │     } else {                                                                                                           
 150 │         kvm->ram_start = mmap_anon_or_hugetlbfs(kvm, hugetlbfs_path, ram_size + KVM_32BIT_GAP_SIZE);                   
 151 │         kvm->ram_size = ram_size + KVM_32BIT_GAP_SIZE;                                                                 
 152 │         if (kvm->ram_start != MAP_FAILED)                                                                              
 153 │             /*                                                                                                         
 154 │              * We mprotect the gap (see kvm__init_ram() for details) PROT_NONE so that                                 
 155 │              * if we accidently write to it, we will know.                                                             
 156 │              */                                                                                                        
 157 │             mprotect(kvm->ram_start + KVM_32BIT_GAP_START, KVM_32BIT_GAP_SIZE, PROT_NONE);                             
 158 │     }                                                                                                                  
 159 │     if (kvm->ram_start == MAP_FAILED)                                                                                  
 160 │         die("out of memory");                                                                                          
 161 │                                                                                                                        
 162 │     madvise(kvm->ram_start, kvm->ram_size, MADV_MERGEABLE);                                                            
 163 │                                                                                                                        
 164 │     ret = ioctl(kvm->vm_fd, KVM_CREATE_IRQCHIP);                                                                       
 165 │     if (ret < 0)                                                                                                       
 166 │         die_perror("KVM_CREATE_IRQCHIP ioctl");                                                                        
 167 │ }

Interestingly, kernel Documentation/virtual/kvm/api.txt reads:

Capability: KVM_CAP_PIT2
Architectures: x86
Type: vm ioctl
Parameters: struct kvm_pit_config (in)
Returns: 0 on success, -1 on error

Creates an in-kernel device model for the i8254 PIT. This call is only valid
after enabling in-kernel irqchip support via KVM_CREATE_IRQCHIP. The following
parameters have to be passed:

Question: should CREATE_PIT2 be executed after CREATE_IRQCHIP in line 164?

best,
evrim.

Convert Virtual Address of a workload inside vm to kvmtool address

Is this possible to convert virtual address of a workload inside virtual machine to kvmtool address?

can not get image from http://wiki.qemu.org/download/linux-0.2.img.bz2

I am trying to learn the project ,but wget http://wiki.qemu.org/download/linux-0.2.img.bz2 return me 404

linux image vs guest memory size

kvmtool/riscv/kvm.c

Lines 101 to 105 in e17d182

 /* 

  * Linux requires the initrd and dtb to be mapped inside lowmem, 

  * so we can't just place them at the top of memory. 

  */ 

 limit = kvm->ram_start + min(kvm->ram_size, (u64)SZ_256M) - 1;

Might be a noob question, but isn't this line counter-intuitive? If the linux image is large enough (> 256M), then we will fail on the later file read even if we keep increasing guest memory size with -m. At least for me, this was confusing because I kept hitting the same kernel image too big to fit in guest memory. message even when I knew I had allocated enough.

A question about the code in "kvmtool/x86/mptable.c"

Hi, I'm a green hand about kvmtool but I've recently participated in a project related to it.
But when I viewed the underlined file, I found codes as followed.
mpc_intsrc->irqtype = mp_ExtINT;
mpc_intsrc->irqtype = mp_INT;
I have no idea if it's my own misunderstanding or an error. I tried to searched it on Internet, but nothing of much help.
So I'm looking forward to seeking help from developers.

KVM_32BIT_GAP

Hello,

kvm.c<x86> reads:

  80 │ /*                                                                                                                     
  81 │  * Allocating RAM size bigger than 4GB requires us to leave a gap                                                      
  82 │  * in the RAM which is used for PCI MMIO, hotplug, and unconfigured                                                    
  83 │  * devices (see documentation of e820_setup_gap() for details).                                                        
  84 │  *                                                                                                                     
  85 │  * If we're required to initialize RAM bigger than 4GB, we will create                                                 
  86 │  * a gap between 0xe0000000 and 0x100000000 in the guest virtual mem space.                                            
  87 │  */
  88 │ 
  89 │ void kvm__init_ram(struct kvm *kvm)                                                                                    
  90 │ {                                                                                                                      
  91 │     u64 phys_start, phys_size;                                                                                         
  92 │     void    *host_mem;

kvm-arch.h<x86> reads:

   9 │ 
  10 │ /*                                                                                                                     
  11 │  * The hole includes VESA framebuffer and PCI memory.                                                                  
  12 │  */
  13 │ #define KVM_32BIT_MAX_MEM_SIZE  (1ULL << 32)                                      
  14 │ #define KVM_32BIT_GAP_SIZE  (768 << 20)                                       
  15 │ #define KVM_32BIT_GAP_START (KVM_32BIT_MAX_MEM_SIZE - KVM_32BIT_GAP_SIZE) 
  17 │ #define KVM_MMIO_START      KVM_32BIT_GAP_START

Gdb tells:

(gdb) p/x (1ULL << 32) - (768 << 20)
$1 = 0xd0000000

confused ⭕️

best,
evrim.

‘value’may be used uninitialized in this function `kbd_io`

When build with gcc (GCC) 8.4.1, i got a error

hw/i8042.c: In function ‘kbd_io’:
hw/i8042.c:153:19: error: ‘value’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
   state.write_cmd = val;
   ~~~~~~~~~~~~~~~~^~~~~
hw/i8042.c:298:5: note: ‘value’ was declared here
  u8 value;
     ^~~~~
cc1: all warnings being treated as errors

Writting to ioport ( /dev/port )

Is this posible to write more than 8 bytes to ioport and kvmtool receive all these bytes?

when assigning devices using VFIO allows the guest to have direct access to the device of nvme, nvme0: I/O tag 4 (0004) QID 0 timeout

When SR-IOV capable NVMe PCIe device is passed through to the guest vm using lkvm VFIO functionality (--vfio-pci), "nvme0: I/O tag 4 (0004) QID 0 timeout" is observed.

the following is lkvm cmds and logs.

lkvm cmd

lkvm run -m 512 -c1 --console serial -p "console=ttyS0 earlycon" -k Image -d rootfs.ext2 --vfio-pci 0000:00:01.1

# lspci -v
00:00.0 Non-Volatile memory controller: Red Hat, Inc. QEMU NVM Express Controller (rev 02) (prog-if 02 [NVM Express])
        Subsystem: Red Hat, Inc. Device 1100
        Flags: fast devsel
        Memory at 40000000 (32-bit, non-prefetchable) [size=16K]
        Capabilities: [40] MSI-X: Enable- Count=1 Masked-
        Capabilities: [80] Express Root Complex Integrated Endpoint, MSI 00

kernel log

[    1.527082] pci 0000:00:00.0: BAR 0 [mem 0x40000000-0x40003fff]: assigned
[    1.533870] pci 0000:00:01.0: BAR 2 [mem 0x40004000-0x400043ff]: assigned
[    1.541026] pci 0000:00:02.0: BAR 2 [mem 0x40004400-0x400047ff]: assigned
[    1.547329] pci 0000:00:01.0: BAR 0 [io  0x0100-0x01ff]: assigned
[    1.553120] pci 0000:00:01.0: BAR 1 [mem 0x40004800-0x400048ff]: assigned
[    1.559346] pci 0000:00:02.0: BAR 0 [io  0x0200-0x02ff]: assigned
[    1.566536] pci 0000:00:02.0: BAR 1 [mem 0x40004900-0x400049ff]: assigned
[    1.586236] nvme nvme0: pci function 0000:00:00.0
[    1.771708] nvme nvme0: failed to register the CMB
[   62.601763] nvme nvme0: I/O tag 4 (0004) QID 0 timeout, disable controller
[   62.614979] nvme nvme0: Identify Controller failed (-4)
[   62.633939] nvme 0000:00:00.0: probe with driver nvme failed with error -5

But save device behavaves correctly using qemu utils.

The following is logs.

00:01.0 Non-Volatile memory controller: Red Hat, Inc. QEMU NVM Express Controller (rev 02) (prog-if 02 [NVM Express])
        Subsystem: Red Hat, Inc. Device 1100
        Flags: bus master, fast devsel, latency 0
        Memory at 400000000 (64-bit, non-prefetchable) [size=16K]
        Capabilities: [40] MSI-X: Enable+ Count=1 Masked-
        Capabilities: [80] Express Root Complex Integrated Endpoint, MSI 00
        Capabilities: [60] Power Management version 3
        Kernel driver in use: nvme

How can I solve this problem with kvmtool?

kvmtool / kvmtool Goto Github PK

kvmtool's Introduction

kvmtool's People

Contributors

Stargazers

Watchers

Forkers

kvmtool's Issues

How to test riscv guest interrupt

KVM_CREATE_PIT2

Convert Virtual Address of a workload inside vm to kvmtool address

can not get image from http://wiki.qemu.org/download/linux-0.2.img.bz2

linux image vs guest memory size

A question about the code in "kvmtool/x86/mptable.c"

KVM_32BIT_GAP

‘value’may be used uninitialized in this function `kbd_io`

Writting to ioport ( /dev/port )

when assigning devices using VFIO allows the guest to have direct access to the device of nvme, nvme0: I/O tag 4 (0004) QID 0 timeout

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	/*
	* Linux requires the initrd and dtb to be mapped inside lowmem,
	* so we can't just place them at the top of memory.
	*/
	limit = kvm->ram_start + min(kvm->ram_size, (u64)SZ_256M) - 1;