Re: [Qemu-devel] Re: [PATCH] qemu-kvm: fix segfault when running kvm without /dev/kvm, falling back to non-accelerated mode
On Fri, 4 Sep 2009 18:46:23 -0300 Marcelo Tosatti wrote: > On Fri, Sep 04, 2009 at 06:39:25PM -0300, Luiz Capitulino wrote: > > > Sure, Marcelo. It's attached. > > > > > > I tested it, and it still does avoid the segfault. > > > > > > Luiz, could you re-test this patch on your side too? > > > > I'm getting rejections, are you sure it's against upstream? > > Its againts 0.11-stable branch. duh. :) Works for me on 0.11-stable: Tested-by: Luiz Capitulino -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [Qemu-devel] Re: [PATCH] qemu-kvm: fix segfault when running kvm without /dev/kvm, falling back to non-accelerated mode
On Fri, Sep 04, 2009 at 06:39:25PM -0300, Luiz Capitulino wrote:
> > Sure, Marcelo. It's attached.
> >
> > I tested it, and it still does avoid the segfault.
> >
> > Luiz, could you re-test this patch on your side too?
>
> I'm getting rejections, are you sure it's against upstream?
Its againts 0.11-stable branch. Try this against master:
qemu-kvm segfaults on systems without access to /dev/kvm.
The global kvm_allowed is being set too late in vl.c.
This patch moves the kvm initialization a bit higher in the
vl.c main, just after the daemonize fork.
This fix is intended to be a short term solution, solving the
segfaults.
In the longer term, the suggested approach requires a bit more
development and testing:
* If no arg given => try kvm, try kqemu, try tcg
* If --accelmode arg given => try $arg, and fail if unavailable
Signed-off-by: Dustin Kirkland
diff --git a/vl.c b/vl.c
index 9f03d85..3485ce6 100644
--- a/vl.c
+++ b/vl.c
@@ -5823,6 +5823,20 @@ int main(int argc, char **argv, char **envp)
signal(SIGTTIN, SIG_IGN);
}
+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 (pid_file && qemu_create_pidfile(pid_file) != 0) {
if (daemonize) {
uint8_t status = 1;
@@ -5983,20 +5997,6 @@ int main(int argc, char **argv, char **envp)
}
}
-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) {
--
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Re: [Qemu-devel] Re: [PATCH] qemu-kvm: fix segfault when running kvm without /dev/kvm, falling back to non-accelerated mode
On Fri, 4 Sep 2009 14:38:30 -0500 Dustin Kirkland wrote: > On Fri, Sep 4, 2009 at 11:36 AM, Marcelo Tosatti wrote: > > 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 wrote: > >> > > > On Thu, Sep 3, 2009 at 3:01 PM, Mark McLoughlin > >> > > > 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 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? > > Sure, Marcelo. It's attached. > > I tested it, and it still does avoid the segfault. > > Luiz, could you re-test this patch on your side too? I'm getting rejections, are you sure it's against upstream? -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
