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[libvirt] Re: virDomainMemoryPeek for Xen?
by Richard W.M. Jones 13 Aug '08

13 Aug '08

On Wed, Aug 13, 2008 at 01:19:42PM +0900, Jun Koi wrote: > According to the comment in your driver code for virDomainMemoryPeek, > libvirt is not currently supporting Xen. Why is that? As far as I see, > Xen is use the same GPL2 version as libvirt. > > I am thinking about implementing the driver for Xen, so have this question. It'd be really good to have a driver for this for libvirt. QEMU does virtual->physical translation for us, through the guest's CR3 & page tables. [This discussion will concentrate on x86 for the moment :-)] If you look at the qemu source, file target-i386/ helper2.c, function cpu_get_phys_page_debug, you will see the code they use to navigate through the 3 or 4 levels of page tables for i386 & x86-64 respectively. The QEMU memsave command made it almost trivial to write virDomainMemoryPeek (...VIR_MEMORY_VIRTUAL...); On Xen things are a bit different. You can map in physical pages from another guest using the libxc call xc_map_foreign_range. Note that you cannot just call xc_map_foreign_range because the libxc & libvirt licenses are _not_ compatible. So instead you'd need to do the underlying sequence of mmap / ioctl / munmap. (See tools/libxc/ xc_linux.c in the Xen source). But you still need to do virtual to physical page translation, either using the qemu source as an example, or using xc_translate_foreign_address as a guide (or just using the Intel Programmers Reference Manual and doing it from first principles). Another alternative is to implement virDomainMemoryPeek (...VIR_MEMORY_PHYSICAL...). It is not possible to implement this for QEMU at all, at least not without changing QEMU. Implementing this for Xen would be much easier because you don't need to do address translation, but it does push the problem of address translation up to the callers. Places to look in the QEMU source for inspiration: monitor.c:do_memory_save target-i386/helper2.c:cpu_get_phys_page_debug Other places to look in the Xen source for inspiration: tools/libxc/xc_linux.c tools/libxc/xc_pagetab.c tools/xentrace/xenctx.c (thanks Mark McLoughlin) Rich. -- Richard Jones, Emerging Technologies, Red Hat http://et.redhat.com/~rjones virt-top is 'top' for virtual machines. Tiny program with many powerful monitoring features, net stats, disk stats, logging, etc. http://et.redhat.com/~rjones/virt-top

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[libvirt] [PATCH]: ruby-libvirt migration fixes
by Chris Lalancette 13 Aug '08

13 Aug '08

Attached is a relatively simple patch to the ruby-libvirt bindings with some bugfixes for the migrate call. The first problem was that there was no way to pass a "nil" through to the underlying virDomainMigrate() call. This is important because generally the "dname" and "uri" parameters end up being NULL. This patch also makes all the parameters beyond the first 2 optional. I've tested this out by live migrating a KVM guest between two hosts, and this now does what I expect. Signed-off-by: Chris Lalancette <clalance(a)redhat.com>

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[libvirt] PATCH: Block & reset signals when fork/exec'ing children
by Daniel P. Berrange 12 Aug '08

12 Aug '08

The LXC patches identified a race condition between fork/exec'ing child processes and signal handlers. The process using libvirt can have setup arbitrary signal handlers. In the libvirtd case we have one attached to SIGCHILD, and the handler writes to a pipe which is then processeed in the main loop. When you fork() signal handlers are preserved in the child process, but you may well not want the signal handlers to be run in the children - for example in LXC we closed the FD associated the pipe after fork(), and that FD is now asociated with a socket we use to talk to the container. So if the original signal handler is run bad stuff will happen in the child. Now signal handlers will eventually get reset when you exec(), but this leaves open a race condition window between the fork & exec() when we cannot assume it is safe to run the signal handlers from the parent So, this changes the virExec() function so that before fork()ing it blocks all signals. After fork() the parent process can restore its original signal mask. The child process meanwhile calls sigaction() to reset all signal handlers to SIG_DFL, and then unblocks all signals. NB, the child does not restore the parents sig-mask - libvirt can be called from any app, and we don't want to inherit whatever mask the app may have setup. On Linux there is a convenient NSIG constant defined in signal.h telling us how many signals there are. If this isn't defined I simply set it to 32 which is enough for UNIX pre-dating the addition of real-time signals to POSIX. If we find convenient or more appropriate values for other non-Linux OS we can update this as needed. NB I call pthread_sigmask() instead of sigprocmask() when doing the fork/exec, because we cannot assume that the application using libvirt is single-threaded & thus we only want to block signals in the thread doing the fork/exec. Daniel diff -r 1dbfb08d365d src/util.c --- a/src/util.c Thu Aug 07 16:55:11 2008 +0100 +++ b/src/util.c Thu Aug 07 16:55:53 2008 +0100 @@ -37,6 +37,7 @@ #include <sys/wait.h> #endif #include <string.h> +#include <signal.h> #include "c-ctype.h" #ifdef HAVE_PATHS_H @@ -49,6 +50,10 @@ #include "util.h" #include "memory.h" #include "util-lib.c" + +#ifndef NSIG +# define NSIG 32 +#endif #ifndef MIN # define MIN(a, b) ((a) < (b) ? (a) : (b)) @@ -104,9 +109,23 @@ _virExec(virConnectPtr conn, const char *const*argv, int *retpid, int infd, int *outfd, int *errfd, int non_block) { - int pid, null; + int pid, null, i; int pipeout[2] = {-1,-1}; int pipeerr[2] = {-1,-1}; + sigset_t oldmask, newmask; + struct sigaction sig_action; + + /* + * Need to block signals now, so that child process can safely + * kill off caller's signal handlers without a race. + */ + sigfillset(&newmask); + if (pthread_sigmask(SIG_SETMASK, &newmask, &oldmask) < 0) { + ReportError(conn, NULL, NULL, VIR_ERR_INTERNAL_ERROR, + _("cannot block signals: %s"), + strerror(errno)); + return -1; + } if ((null = open(_PATH_DEVNULL, O_RDONLY)) < 0) { ReportError(conn, NULL, NULL, VIR_ERR_INTERNAL_ERROR, @@ -122,6 +141,34 @@ goto cleanup; } + if (outfd) { + if(non_block && + virSetNonBlock(pipeout[0]) == -1) { + ReportError(conn, NULL, NULL, VIR_ERR_INTERNAL_ERROR, + _("Failed to set non-blocking file descriptor flag")); + goto cleanup; + } + + if(virSetCloseExec(pipeout[0]) == -1) { + ReportError(conn, NULL, NULL, VIR_ERR_INTERNAL_ERROR, + _("Failed to set close-on-exec file descriptor flag")); + goto cleanup; + } + } + if (errfd) { + if(non_block && + virSetNonBlock(pipeerr[0]) == -1) { + ReportError(conn, NULL, NULL, VIR_ERR_INTERNAL_ERROR, + _("Failed to set non-blocking file descriptor flag")); + goto cleanup; + } + if(virSetCloseExec(pipeerr[0]) == -1) { + ReportError(conn, NULL, NULL, VIR_ERR_INTERNAL_ERROR, + _("Failed to set close-on-exec file descriptor flag")); + goto cleanup; + } + } + if ((pid = fork()) < 0) { ReportError(conn, NULL, NULL, VIR_ERR_INTERNAL_ERROR, _("cannot fork child process: %s"), strerror(errno)); @@ -132,33 +179,48 @@ close(null); if (outfd) { close(pipeout[1]); - if(non_block) - if(virSetNonBlock(pipeout[0]) == -1) - ReportError(conn, NULL, NULL, VIR_ERR_INTERNAL_ERROR, - _("Failed to set non-blocking file descriptor flag")); - - if(virSetCloseExec(pipeout[0]) == -1) - ReportError(conn, NULL, NULL, VIR_ERR_INTERNAL_ERROR, - _("Failed to set close-on-exec file descriptor flag")); *outfd = pipeout[0]; } if (errfd) { close(pipeerr[1]); - if(non_block) - if(virSetNonBlock(pipeerr[0]) == -1) - ReportError(conn, NULL, NULL, VIR_ERR_INTERNAL_ERROR, - _("Failed to set non-blocking file descriptor flag")); - - if(virSetCloseExec(pipeerr[0]) == -1) - ReportError(conn, NULL, NULL, VIR_ERR_INTERNAL_ERROR, - _("Failed to set close-on-exec file descriptor flag")); *errfd = pipeerr[0]; } *retpid = pid; + + /* Restore our original signal mask now child is safely + running */ + if (pthread_sigmask(SIG_SETMASK, &oldmask, NULL) < 0) { + ReportError(conn, NULL, NULL, VIR_ERR_INTERNAL_ERROR, + _("cannot unblock signals: %s"), + strerror(errno)); + return -1; + } + return 0; } /* child */ + + /* Clear out all signal handlers from parent so nothing + unexpected can happen in our child here */ + sig_action.sa_handler = SIG_DFL; + sig_action.sa_flags = 0; + sigemptyset(&sig_action.sa_mask); + + for (i = 0 ; i < NSIG ; i++) + /* Only possible errors are EFAULT or EINVAL + The former wont happen, the latter we + expect, so no need to check return value */ + sigaction(i, &sig_action, NULL); + + /* Unmask all signals in child, since we've no idea + what the caller's done with their signal mask */ + if (pthread_sigmask(SIG_SETMASK, &oldmask, NULL) < 0) { + ReportError(conn, NULL, NULL, VIR_ERR_INTERNAL_ERROR, + _("cannot unblock signals: %s"), + strerror(errno)); + return -1; + } if (pipeout[0] > 0 && close(pipeout[0]) < 0) _exit(1); -- |: Red Hat, Engineering, London -o- http://people.redhat.com/berrange/ :| |: http://libvirt.org -o- http://virt-manager.org -o- http://ovirt.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: GnuPG: 7D3B9505 -o- F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :|

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[libvirt] [PATCH] rewrite virFileLinkPointsTo
by Jim Meyering 12 Aug '08

12 Aug '08

I've rewritten virFileLinkPointsTo to be a lot simpler, and more importantly, it has far fewer failure points. If anyone wants to preserve the original behavior that makes it fail when the first parameter does not specify a symlink, I can add that. The only difference in behavior would be when the two files are hard-linked. In any case, I'll remove the FIXME comment. The diff below is not very readable. Bottom line, it replaces a pair of functions (the latter is a stub for mingw) with this: #define SAME_INODE(Stat_buf_1, Stat_buf_2) \ ((Stat_buf_1).st_ino == (Stat_buf_2).st_ino \ && (Stat_buf_1).st_dev == (Stat_buf_2).st_dev) int virFileLinkPointsTo(const char *checkLink, const char *checkDest) { struct stat src_sb; struct stat dest_sb; if (stat (checkLink, &src_sb) || stat (checkDest, &dest_sb)) return 0; /* FIXME: if required, lstat checkLink to ensure it's a symlink */ if (! SAME_INODE (src_sb, dest_sb)) { virLog("Link '%s' does not point to '%s', ignoring\n", checkLink, checkDest); return 0; } return 1; } >From 4e70c02e547b078b8f35afd0996b6887e1593afd Mon Sep 17 00:00:00 2001 From: Jim Meyering <meyering(a)redhat.com> Date: Tue, 12 Aug 2008 19:07:46 +0200 Subject: [PATCH] rewrite virFileLinkPointsTo * src/util.c (SAME_INODE): Define. (virFileLinkPointsTo): Rewrite to be more portable and more efficient. --- src/util.c | 97 ++++++----------------------------------------------------- 1 files changed, 10 insertions(+), 87 deletions(-) diff --git a/src/util.c b/src/util.c index 9f056e0..2905a0a 100644 --- a/src/util.c +++ b/src/util.c @@ -397,107 +397,30 @@ int virFileHasSuffix(const char *str, return STREQ(str + len - suffixlen, suffix); } -#ifndef __MINGW32__ +#define SAME_INODE(Stat_buf_1, Stat_buf_2) \ + ((Stat_buf_1).st_ino == (Stat_buf_2).st_ino \ + && (Stat_buf_1).st_dev == (Stat_buf_2).st_dev) int virFileLinkPointsTo(const char *checkLink, const char *checkDest) { - char dest[PATH_MAX]; - char real[PATH_MAX]; - char checkReal[PATH_MAX]; - int n; - - /* read the link destination */ - if ((n = readlink(checkLink, dest, PATH_MAX)) < 0) { - switch (errno) { - case ENOENT: - case ENOTDIR: - return 0; - - case EINVAL: - virLog("File '%s' is not a symlink\n", - checkLink); - return 0; - - } - virLog("Failed to read symlink '%s': %s\n", - checkLink, strerror(errno)); - return 0; - } else if (n >= PATH_MAX) { - virLog("Symlink '%s' contents too long to fit in buffer\n", - checkLink); - return 0; - } + struct stat src_sb; + struct stat dest_sb; - dest[n] = '\0'; + if (stat (checkLink, &src_sb) || stat (checkDest, &dest_sb)) + return 0; - /* make absolute */ - if (dest[0] != '/') { - char dir[PATH_MAX]; - char tmp[PATH_MAX]; - char *p; + /* FIXME: if required, lstat checkLink to ensure it's a symlink */ - strncpy(dir, checkLink, PATH_MAX); - dir[PATH_MAX-1] = '\0'; - - if (!(p = strrchr(dir, '/'))) { - virLog("Symlink path '%s' is not absolute\n", checkLink); - return 0; - } - - if (p == dir) /* handle unlikely root dir case */ - p++; - - *p = '\0'; - - if (virFileBuildPath(dir, dest, NULL, tmp, PATH_MAX) < 0) { - virLog("Path '%s/%s' is too long\n", dir, dest); - return 0; - } - - strncpy(dest, tmp, PATH_MAX); - dest[PATH_MAX-1] = '\0'; - } - - /* canonicalize both paths */ - if (!realpath(dest, real)) { - virLog("Failed to expand path '%s' :%s\n", dest, strerror(errno)); - strncpy(real, dest, PATH_MAX); - real[PATH_MAX-1] = '\0'; - } - - if (!realpath(checkDest, checkReal)) { - virLog("Failed to expand path '%s' :%s\n", checkDest, strerror(errno)); - strncpy(checkReal, checkDest, PATH_MAX); - checkReal[PATH_MAX-1] = '\0'; - } - - /* compare */ - if (STRNEQ(checkReal, real)) { + if (! SAME_INODE (src_sb, dest_sb)) { virLog("Link '%s' does not point to '%s', ignoring\n", - checkLink, checkReal); + checkLink, checkDest); return 0; } return 1; } -#else /* !__MINGW32__ */ - -/* Gnulib has an implementation of readlink which could be used - * to implement this, but it requires LGPLv3. - */ - -int -virFileLinkPointsTo (const char *checkLink ATTRIBUTE_UNUSED, - const char *checkDest ATTRIBUTE_UNUSED) -{ - virLog (_("%s: not implemented\n"), __FUNCTION__); - return 0; -} - -#endif /*! __MINGW32__ */ - int virFileExists(const char *path) { struct stat st; -- 1.6.0.rc2.38.g413e06

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[libvirt] Qemu Monitor
by Listen 12 Aug '08

12 Aug '08

Hi all, A simple question, I hope ;) Is it possible to enable the qemu monitor in libvirt's xml? It need the monitor, to dynamically add a usb device to a windows vm. Regards, Eric

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[libvirt] gnome-applet-vm orphaned
by Karel Zak 12 Aug '08

12 Aug '08

Hi folks, unfortunately, I have not enough time to work on the gnome applet. I'm looking for a new upstream maintainer, or for co-maintainer. Project home page: http://fedorahosted.org/gnome-applet-vm/ Note that the applet does not require any heavy development. Any volunteers around? Karel -- Karel Zak <kzak(a)redhat.com>

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[libvirt] [PATCH] Ensure parted doesn't prompt if labeling disk
by Cole Robinson 12 Aug '08

12 Aug '08

Trying to 'build' a disk pool uses 'parted mklabel' which can prompt for confirmation. Patch adds the '--script' option to remove the chance of this happening. Thanks, Cole

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[libvirt] Announcement of a companion project the "UnifiedSessionsManager"
by acue 12 Aug '08

12 Aug '08

Hello, I would like to announce the unifiedSessionsManager(GPL3, including the claimed inventions), which is based for Xen on the virsh-tool, but basically uses a different approach. I guess it could be a quite usable companion of libvirt for advanced usage and enhanced customizabelity of the handling of huge amounts of virtual and physical machines in a distributed environment. It is targeting on test, development and productive environments. This requirement will particularly arise, when "bulk-core-CPUs" enter the market, providing for independently executed bulks of virtual machines, which may be logically designed as stacked and nested VMs, founding a tree like multi-layered structure of VM clusters. The design-preview as estimated by the unifiedSessionsManager is here the v-component, what could be seen as the extensin of the slogan/concept of a so called virtual appliance, where a full scale VM including it's inherent GuestOS is handeled as a virtual software component. V-Compoents are foreseen to be grouped into clusters of VMs, arranged within a nested VMSTACK and managed - e.g. suspended - as a group of services, founding a combined service by their self. In case this preview becomes reality, this may have an impact on the basic design, particularly the interface design of each of it's components to be stack-aware, thus for libvirt too. For example providing the shutdown of a stack of VMs, including the suspension of machines containing upper VMs, might require some kind of communications and propagation.. The usage of multilayered VMSTACKs is already supported by the unifiedSessionsManager. Particularly MACRO and GROUP features support for handling of the number of entities required to be handled for a VMSTACK. Whereas much of the required functionality from the VMs is simulated, particularly by utilizing a recursive Stack-Propagation based on native access to GuestOSs with SSO-accounts. The concrete supported products of current version 01_07_001b02 are: - GuestOS and HostOS on physical machines: CentOS, Fedora, debian, OpenSUSE, Ubuntu, OpenBSD, Solaris10(limited) - Hypervisors/Emulators: QEMU, Xn, VMware(workstation,server,player) Future Plans are, mostly for the next version already: -Planned-OS: FreeBSD, NetBSD, Solaris10(complete), OpenSolaris, ScientificLinux -Planned-OS: eCos(?), uCLinux(several ARCH), SkyEye, ... -Planned-VM: VirtualBOX(evaluation first), OpenVZ(evaluation first) .Introduction of a LDAP based nameservice for VMs. -Evaluation of:Cygwin The Idea was the easy to adapt utilization of a minimalistic-bash-scripts only implementation for setting up a unified wrapper interface customizable for almost any kind of user sessions by almost anyone. Even though I would prefer now at least Perl or for specific parts full scale C/C++ code and Java/JavaScript for some administrative parts. The managed user environment comprises sessions to VMs which could be allocated in a nested multilayered VMSTACK as well as within a PM, which are physical machines - layer-0 entities. Also HOSTs sessions as native access to GuestOSs are integrated. Additionally a simple implemented but with sophisticated functionally equipped cache database is introduced in order to support for hundreds and thousands of virtual machines to be managed, with an average query-response-time for single-level-filters of less than 1second. Results are measured with an average of 0.3-0.8seconds in the ref.-env., even though bash and awk is mainly used only with an Office-Compatible record format. Information could be found within the User-Manual, which has more than 600pages, and within the sources of more than 110.000LinesOfCode. The following sites provide downloads: http://www.heise.de/software/download/unified_sessions_manager_ctys/51630 http://www.unifiedsessionsmanager.org http://www.unifiedsessionsmanager.eu http://sourceforge.net/projects/ctys (sourceforge not yet complete) (berlios follows) There are basically three reasons for sending this Mail: 1. Announcing a new supplemental project focusing on usage of distributed and stacked VMs 2. Getting some feedback and ideas for the future direction of the development of libvirt and the unifiedSessionsManager. 3. Probably initiation of setting up a common overall concept for the future vision of an IT environment and it's integrated handling of VMs. And of course, I would appreciate, if the current version already is of some benefit for the OpenSource community. Yours Sincerely Arno-Can Uestuensoez -- ---------------------------------------------------------------------------- Arno-Can Uestuensoez www.i4p.de / www.i4p.com

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[libvirt] [PATCH/RFC]: hostdev passthrough support
by Guido Günther 12 Aug '08

12 Aug '08

Hi, attached is some basic support for host device passthrough. It enables you to passthrough usb devices in qemu/kvm via: <devices> <hostdev type='usb' vendor='0204' product='6025'/> <hostdev type='usb' bus='001' device='007'/> </devices> I didn't implement unplug yet since this needs some modifications to qemu/kvm to be able to identify the correct device to unplug. Does this look reasonable? -- Guido

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[libvirt] [PATCH] fix MinGW compilation(200808)
by Atsushi SAKAI 12 Aug '08

12 Aug '08

Hi, Currently, compilation for MinGW is broken. Here is the patch. But configure script option for MinGW is changed from previous posting. https://www.redhat.com/archives/libvir-list/2008-June/msg00145.html Currently, it should do # ./configure --without-xen --without-qemu --without-sasl --without-lxc --without-openvz --without-libvirtd --without-test currently following 3 make works, make make install make check I do not know why syntax-check is not exist on Makefile on MinGW. src/domain_conf.c | 2 ++ src/network_conf.c | 2 ++ src/virsh.c | 8 ++++++++ tests/testutilsxen.c | 2 ++ 4 files changed, 14 insertions(+) Thanks Atsushi SAKAI

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