| Message ID | d9c105ea0909031031g463aa731j846dd73d4c158ebc@mail.gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Sep 03, 2009 at 12:31:33PM -0500, Dustin Kirkland wrote: > qemu-kvm: fix segfault when running kvm without /dev/kvm, falling back > to non-accelerated mode > > We're seeing segfaults on systems without access to /dev/kvm. It > looks like the global kvm_allowed is being set just a little too late > in vl.c. This patch moves the kvm initialization a bit higher in the > vl.c main, just after options processing, and solves the segfaults. > We're carrying this patch in Ubuntu 9.10 Alpha. Please apply > upstream, or advise if and why this might not be the optimal solution. > > Signed-off-by: Dustin Kirkland <kirkland@canonical.com> Dustin, I think its safer to move it just after fork() from -daemonize, to make sure no state initialized by kvm_init is lost in the child. > Move the kvm_init() call a bit higher to fix a segfault when > /dev/kvm is not available. The kvm_allowed global needs > to be set correctly a little earlier. > > Signed-off-by: Dustin Kirkland <kirkland@canonical.com> > > > --- qemu-kvm-0.11.0~rc1.orig/vl.c > +++ qemu-kvm-0.11.0~rc1/vl.c > @@ -5748,6 +5748,20 @@ > } > } > > + if (kvm_enabled()) { > + int ret; > + > + ret = kvm_init(smp_cpus); > + if (ret < 0) { > +#if defined(KVM_UPSTREAM) || defined(NO_CPU_EMULATION) > + fprintf(stderr, "failed to initialize KVM\n"); > + exit(1); > +#endif > + fprintf(stderr, "Could not initialize KVM, will disable KVM support\n"); > + kvm_allowed = 0; > + } > + } > + > /* If no data_dir is specified then try to find it relative to the > executable path. */ > if (!data_dir) { > @@ -6008,20 +6022,6 @@ > } > } > > - if (kvm_enabled()) { > - int ret; > - > - ret = kvm_init(smp_cpus); > - if (ret < 0) { > -#if defined(KVM_UPSTREAM) || defined(NO_CPU_EMULATION) > - fprintf(stderr, "failed to initialize KVM\n"); > - exit(1); > -#endif > - fprintf(stderr, "Could not initialize KVM, will disable KVM support\n"); > - kvm_allowed = 0; > - } > - } > - > if (monitor_device) { > monitor_hd = qemu_chr_open("monitor", monitor_device, NULL); > if (!monitor_hd) { -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, 2009-09-03 at 12:31 -0500, Dustin Kirkland wrote: > qemu-kvm: fix segfault when running kvm without /dev/kvm, falling back > to non-accelerated mode > > We're seeing segfaults on systems without access to /dev/kvm. It > looks like the global kvm_allowed is being set just a little too late > in vl.c. This patch moves the kvm initialization a bit higher in the > vl.c main, just after options processing, and solves the segfaults. > We're carrying this patch in Ubuntu 9.10 Alpha. Please apply > upstream, or advise if and why this might not be the optimal solution. Ah discussion about an alternative fix for this fizzled out recently: http://www.mail-archive.com/kvm@vger.kernel.org/msg19890.html Cheers, Mark. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, 3 Sep 2009 12:31:33 -0500 Dustin Kirkland <kirkland@canonical.com> wrote: > qemu-kvm: fix segfault when running kvm without /dev/kvm, falling back > to non-accelerated mode > > We're seeing segfaults on systems without access to /dev/kvm. It > looks like the global kvm_allowed is being set just a little too late > in vl.c. This patch moves the kvm initialization a bit higher in the > vl.c main, just after options processing, and solves the segfaults. > We're carrying this patch in Ubuntu 9.10 Alpha. Please apply > upstream, or advise if and why this might not be the optimal solution. > > Signed-off-by: Dustin Kirkland <kirkland@canonical.com> Fixes the problem to me: Tested-by: Luiz Capitulino <lcapitulino@redhat.com> -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Sep 3, 2009 at 3:01 PM, Mark McLoughlin<markmc@redhat.com> wrote: > On Thu, 2009-09-03 at 12:31 -0500, Dustin Kirkland wrote: >> qemu-kvm: fix segfault when running kvm without /dev/kvm, falling back >> to non-accelerated mode >> >> We're seeing segfaults on systems without access to /dev/kvm. Â It >> looks like the global kvm_allowed is being set just a little too late >> in vl.c. Â This patch moves the kvm initialization a bit higher in the >> vl.c main, just after options processing, and solves the segfaults. >> We're carrying this patch in Ubuntu 9.10 Alpha. Â Please apply >> upstream, or advise if and why this might not be the optimal solution. > > Ah discussion about an alternative fix for this fizzled out recently: > > Â http://www.mail-archive.com/kvm@vger.kernel.org/msg19890.html Ah, thanks Mark. In that thread, I found Daniel's suggestion the most reasonable, and user-friendly: On Mon, Jul 27, 2009 at 1:44 PM, Daniel P. Berrange<berrange@redhat.com> wrote: > Well, we could go for logic like: > > * No arg given => try kvm, try kqemu, try tcg > * --accelmode arg given => try $arg, and fail if unavailable > > then libvirt would simply always supply --accelmode for all VMs, > while people running qemu manually would get best available :-Dustin -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Sep 3, 2009 at 6:48 PM, Dustin Kirkland<kirkland@canonical.com> wrote: > On Thu, Sep 3, 2009 at 3:01 PM, Mark McLoughlin<markmc@redhat.com> wrote: >> On Thu, 2009-09-03 at 12:31 -0500, Dustin Kirkland wrote: >>> qemu-kvm: fix segfault when running kvm without /dev/kvm, falling back >>> to non-accelerated mode >>> >>> We're seeing segfaults on systems without access to /dev/kvm.  It >>> looks like the global kvm_allowed is being set just a little too late >>> in vl.c.  This patch moves the kvm initialization a bit higher in the >>> vl.c main, just after options processing, and solves the segfaults. >>> We're carrying this patch in Ubuntu 9.10 Alpha.  Please apply >>> upstream, or advise if and why this might not be the optimal solution. >> >> Ah discussion about an alternative fix for this fizzled out recently: >> >>  http://www.mail-archive.com/kvm@vger.kernel.org/msg19890.html > > Ah, thanks Mark.  In that thread, I found Daniel's suggestion the most > reasonable, and user-friendly: > > On Mon, Jul 27, 2009 at 1:44 PM, Daniel P. Berrange<berrange@redhat.com> wrote: >> Well, we could go for logic like: >> >>  * No arg given      => try kvm, try kqemu, try tcg >>  * --accelmode arg given => try $arg, and fail if unavailable >> >> then libvirt would simply always supply --accelmode for all VMs, >> while people running qemu manually would get best available I sent some patches to do that, but they were incomplete, and I was preempted by something else. If you want, you can wait for my cycles to come back, or pick from where I left
On Thu, 2009-09-03 at 19:18 -0300, Glauber Costa wrote: > On Thu, Sep 3, 2009 at 6:48 PM, Dustin Kirkland<kirkland@canonical.com> wrote: > > On Thu, Sep 3, 2009 at 3:01 PM, Mark McLoughlin<markmc@redhat.com> wrote: > >> On Thu, 2009-09-03 at 12:31 -0500, Dustin Kirkland wrote: > >>> qemu-kvm: fix segfault when running kvm without /dev/kvm, falling back > >>> to non-accelerated mode > >>> > >>> We're seeing segfaults on systems without access to /dev/kvm. It > >>> looks like the global kvm_allowed is being set just a little too late > >>> in vl.c. This patch moves the kvm initialization a bit higher in the > >>> vl.c main, just after options processing, and solves the segfaults. > >>> We're carrying this patch in Ubuntu 9.10 Alpha. Please apply > >>> upstream, or advise if and why this might not be the optimal solution. > >> > >> Ah discussion about an alternative fix for this fizzled out recently: > >> > >> http://www.mail-archive.com/kvm@vger.kernel.org/msg19890.html > > > > Ah, thanks Mark. In that thread, I found Daniel's suggestion the most > > reasonable, and user-friendly: > > > > On Mon, Jul 27, 2009 at 1:44 PM, Daniel P. Berrange<berrange@redhat.com> wrote: > >> Well, we could go for logic like: > >> > >> * No arg given => try kvm, try kqemu, try tcg > >> * --accelmode arg given => try $arg, and fail if unavailable > >> > >> then libvirt would simply always supply --accelmode for all VMs, > >> while people running qemu manually would get best available > I sent some patches to do that, but they were incomplete, and I was > preempted by something else. > If you want, you can wait for my cycles to come back, or pick from where I left In the meantime, can we commit to stable-0.11 either Dustin's fix or this: http://git.et.redhat.com/?p=qemu-fedora.git;a=commitdiff;h=aa1620047b Cheers, Mark. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri, 2009-09-04 at 08:22 +0100, Mark McLoughlin wrote: > On Thu, 2009-09-03 at 19:18 -0300, Glauber Costa wrote: > > On Thu, Sep 3, 2009 at 6:48 PM, Dustin Kirkland<kirkland@canonical.com> wrote: > > > On Thu, Sep 3, 2009 at 3:01 PM, Mark McLoughlin<markmc@redhat.com> wrote: > > >> On Thu, 2009-09-03 at 12:31 -0500, Dustin Kirkland wrote: > > >>> qemu-kvm: fix segfault when running kvm without /dev/kvm, falling back > > >>> to non-accelerated mode > > >>> > > >>> We're seeing segfaults on systems without access to /dev/kvm. It > > >>> looks like the global kvm_allowed is being set just a little too late > > >>> in vl.c. This patch moves the kvm initialization a bit higher in the > > >>> vl.c main, just after options processing, and solves the segfaults. > > >>> We're carrying this patch in Ubuntu 9.10 Alpha. Please apply > > >>> upstream, or advise if and why this might not be the optimal solution. > > >> > > >> Ah discussion about an alternative fix for this fizzled out recently: > > >> > > >> http://www.mail-archive.com/kvm@vger.kernel.org/msg19890.html > > > > > > Ah, thanks Mark. In that thread, I found Daniel's suggestion the most > > > reasonable, and user-friendly: > > > > > > On Mon, Jul 27, 2009 at 1:44 PM, Daniel P. Berrange<berrange@redhat.com> wrote: > > >> Well, we could go for logic like: > > >> > > >> * No arg given => try kvm, try kqemu, try tcg > > >> * --accelmode arg given => try $arg, and fail if unavailable > > >> > > >> then libvirt would simply always supply --accelmode for all VMs, > > >> while people running qemu manually would get best available > > I sent some patches to do that, but they were incomplete, and I was > > preempted by something else. > > If you want, you can wait for my cycles to come back, or pick from where I left Thanks for the pointer, Glauber. My cycles a bit constrained too, but I'll have a look when I get a chance. > In the meantime, can we commit to stable-0.11 either Dustin's fix or > this: > > http://git.et.redhat.com/?p=qemu-fedora.git;a=commitdiff;h=aa1620047b +1. We're looking for something agreeable in stable-0.11, that solves the segfault and proceeds without VT acceleration.
On Fri, Sep 04, 2009 at 11:06:38AM -0500, Dustin Kirkland wrote: > On Fri, 2009-09-04 at 08:22 +0100, Mark McLoughlin wrote: > > On Thu, 2009-09-03 at 19:18 -0300, Glauber Costa wrote: > > > On Thu, Sep 3, 2009 at 6:48 PM, Dustin Kirkland<kirkland@canonical.com> wrote: > > > > On Thu, Sep 3, 2009 at 3:01 PM, Mark McLoughlin<markmc@redhat.com> wrote: > > > >> On Thu, 2009-09-03 at 12:31 -0500, Dustin Kirkland wrote: > > > >>> qemu-kvm: fix segfault when running kvm without /dev/kvm, falling back > > > >>> to non-accelerated mode > > > >>> > > > >>> We're seeing segfaults on systems without access to /dev/kvm. It > > > >>> looks like the global kvm_allowed is being set just a little too late > > > >>> in vl.c. This patch moves the kvm initialization a bit higher in the > > > >>> vl.c main, just after options processing, and solves the segfaults. > > > >>> We're carrying this patch in Ubuntu 9.10 Alpha. Please apply > > > >>> upstream, or advise if and why this might not be the optimal solution. > > > >> > > > >> Ah discussion about an alternative fix for this fizzled out recently: > > > >> > > > >> http://www.mail-archive.com/kvm@vger.kernel.org/msg19890.html > > > > > > > > Ah, thanks Mark. In that thread, I found Daniel's suggestion the most > > > > reasonable, and user-friendly: > > > > > > > > On Mon, Jul 27, 2009 at 1:44 PM, Daniel P. Berrange<berrange@redhat.com> wrote: > > > >> Well, we could go for logic like: > > > >> > > > >> * No arg given => try kvm, try kqemu, try tcg > > > >> * --accelmode arg given => try $arg, and fail if unavailable > > > >> > > > >> then libvirt would simply always supply --accelmode for all VMs, > > > >> while people running qemu manually would get best available > > > I sent some patches to do that, but they were incomplete, and I was > > > preempted by something else. > > > If you want, you can wait for my cycles to come back, or pick from where I left > > Thanks for the pointer, Glauber. My cycles a bit constrained too, but > I'll have a look when I get a chance. > > > In the meantime, can we commit to stable-0.11 either Dustin's fix or > > this: > > > > http://git.et.redhat.com/?p=qemu-fedora.git;a=commitdiff;h=aa1620047b > > +1. We're looking for something agreeable in stable-0.11, that solves > the segfault and proceeds without VT acceleration. Dustin, Can you please resend the patch with the suggestion i made earlier, for stable-0.11? -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Move the kvm_init() call a bit higher to fix a segfault when /dev/kvm is not available. The kvm_allowed global needs to be set correctly a little earlier. Signed-off-by: Dustin Kirkland <kirkland@canonical.com> --- qemu-kvm-0.11.0~rc1.orig/vl.c +++ qemu-kvm-0.11.0~rc1/vl.c @@ -5748,6 +5748,20 @@ } } + if (kvm_enabled()) { + int ret; + + ret = kvm_init(smp_cpus); + if (ret < 0) { +#if defined(KVM_UPSTREAM) || defined(NO_CPU_EMULATION) + fprintf(stderr, "failed to initialize KVM\n"); + exit(1); +#endif + fprintf(stderr, "Could not initialize KVM, will disable KVM support\n"); + kvm_allowed = 0; + } + } + /* If no data_dir is specified then try to find it relative to the executable path. */ if (!data_dir) { @@ -6008,20 +6022,6 @@ } } - if (kvm_enabled()) { - int ret; - - ret = kvm_init(smp_cpus); - if (ret < 0) { -#if defined(KVM_UPSTREAM) || defined(NO_CPU_EMULATION) - fprintf(stderr, "failed to initialize KVM\n"); - exit(1); -#endif - fprintf(stderr, "Could not initialize KVM, will disable KVM support\n"); - kvm_allowed = 0; - } - } - if (monitor_device) { monitor_hd = qemu_chr_open("monitor", monitor_device, NULL); if (!monitor_hd) {
qemu-kvm: fix segfault when running kvm without /dev/kvm, falling back to non-accelerated mode We're seeing segfaults on systems without access to /dev/kvm. It looks like the global kvm_allowed is being set just a little too late in vl.c. This patch moves the kvm initialization a bit higher in the vl.c main, just after options processing, and solves the segfaults. We're carrying this patch in Ubuntu 9.10 Alpha. Please apply upstream, or advise if and why this might not be the optimal solution. Signed-off-by: Dustin Kirkland <kirkland@canonical.com>