> -----Original Message----- > From: Xen-devel <xen-devel-boun...@lists.xenproject.org> On Behalf Of Tamas K > Lengyel > Sent: 01 June 2020 14:22 > To: xen-devel@lists.xenproject.org > Cc: Kevin Tian <kevin.t...@intel.com>; Stefano Stabellini > <sstabell...@kernel.org>; Tamas K Lengyel > <tamas.leng...@intel.com>; Jun Nakajima <jun.nakaj...@intel.com>; Wei Liu > <w...@xen.org>; Andrew Cooper > <andrew.coop...@citrix.com>; Ian Jackson <ian.jack...@eu.citrix.com>; George > Dunlap > <george.dun...@citrix.com>; Tamas K Lengyel <ta...@tklengyel.com>; Jan > Beulich <jbeul...@suse.com>; > Anthony PERARD <anthony.per...@citrix.com>; Julien Grall <jul...@xen.org>; > Roger Pau Monné > <roger....@citrix.com> > Subject: [PATCH v19 for-4.14 00/13] VM forking
Hi, This series looks to be largely un-acked so, since we are now past the freeze date, I don't really think it can go into 4.14. Is there a particular reason that you think it should be considered? Paul > > The following patches are part of the series that implement VM forking for > Intel HVM guests to allow for the fast creation of identical VMs without the > assosciated high startup costs of booting or restoring the VM from a savefile. > > JIRA issue: https://xenproject.atlassian.net/browse/XEN-89 > > The fork operation is implemented as part of the "xl fork-vm" command: > xl fork-vm -C <config> -Q <qemu-save-file> <parent_domid> > > By default a fully functional fork is created. The user is in charge however > to > create the appropriate config file for the fork and to generate the QEMU save > file before the fork-vm call is made. The config file needs to give the > fork a new name at minimum but other settings may also require changes. > Certain > settings in the config file of both the parent and the fork have to be set to > default. Details are documented. > > The interface also allows to split the forking into two steps: > xl fork-vm --launch-dm no \ > -m <max-vcpus> \ > -p <parent_domid> > xl fork-vm --launch-dm late \ > -C <config_file_for_fork> \ > -Q <qemu_save_file> \ > <fork_domid> > > The split creation model is useful when the VM needs to be created as fast as > possible. The forked VM can be unpaused without the device model being > launched > to be monitored and accessed via VMI. Note however that without its device > model running (depending on what is executing in the VM) it is bound to > misbehave or even crash when its trying to access devices that would be > emulated by QEMU. We anticipate that for certain use-cases this would be an > acceptable situation, in case for example when fuzzing is performed of code > segments that don't access such devices. > > Launching the device model requires the QEMU Xen savefile to be generated > manually from the parent VM. This can be accomplished simply by connecting to > its QMP socket and issuing the "xen-save-devices-state" command. For example > using the standard tool socat these commands can be used to generate the file: > socat - UNIX-CONNECT:/var/run/xen/qmp-libxl-<parent_domid> > { "execute": "qmp_capabilities" } > { "execute": "xen-save-devices-state", \ > "arguments": { "filename": "/path/to/save/qemu_state", \ > "live": false} } > > The series has been tested with Windows VMs and functions as expected. Linux > VMs when forked from a running VM will have a frozen VNC screen. Linux VMs at > this time can only be forked with a working device model when the parent VM > was > restored from a snapshot using "xl restore -p". This is a known limitation due > to Linux VMs having to be made aware of being saved/migrated. > > New in v19: > Including all the patches currently outstanding into the series > Breaking up libxl/xl patch to many sub-patches to make it easier to > review > libxl/xl is now reduced to the bare essential to launch QEMU for a VM > fork > > Tamas K Lengyel (13): > x86/mem_sharing: block interrupt injection for forks > tools/libxc: xc_memshr_fork with interrupts blocked > tools/libxl: Split libxl__domain_make > tools/libxl: populate xenstore entries when launching dm for VM fork > tools/libxl: Add checks for dm_restore_file > tools/libxl: adjust domcreate_bootloader_done > tools/libxl: Adjust libxl__build_pre > tools/libxl: Adjust libxl__build_post > tools/libxl: libxl__build_hvm_fork > tools/libxl: set QEMU saved_state from dm_restore_file > tools/libxl: Add VM forking public functions > tools/xl: Add xl fork-vm command > tools/xl: document fork-vm command > > docs/man/xl.1.pod.in | 39 +++++++++ > tools/libxc/include/xenctrl.h | 3 +- > tools/libxc/xc_memshr.c | 4 +- > tools/libxl/libxl.h | 10 +++ > tools/libxl/libxl_create.c | 134 +++++++++++++++++++++++++------ > tools/libxl/libxl_dm.c | 2 +- > tools/libxl/libxl_dom.c | 59 +++++++++++--- > tools/libxl/libxl_internal.h | 5 +- > tools/libxl/libxl_types.idl | 1 + > tools/xl/Makefile | 2 +- > tools/xl/xl.h | 4 + > tools/xl/xl_cmdtable.c | 13 +++ > tools/xl/xl_forkvm.c | 122 ++++++++++++++++++++++++++++ > tools/xl/xl_vmcontrol.c | 13 +++ > xen/arch/x86/hvm/vmx/intr.c | 6 ++ > xen/arch/x86/mm/mem_sharing.c | 6 +- > xen/include/asm-x86/hvm/domain.h | 2 +- > xen/include/public/memory.h | 3 + > 18 files changed, 383 insertions(+), 45 deletions(-) > create mode 100644 tools/xl/xl_forkvm.c > > -- > 2.25.1 >
