On Tue, May 07, 2013 at 05:54:20PM +0200, Cornelia Huck wrote: > On Tue, 7 May 2013 22:54:16 +0800 > Asias He <asias@xxxxxxxxxx> wrote: > > > In commit a0f155e96 'KVM: Initialize irqfd from kvm_init()', when > > kvm_init() is called the second time (e.g kvm-amd.ko and kvm-intel.ko), > > kvm_arch_init() will fail with -EEXIST, then kvm_irqfd_exit() will be > > called on the error handling path. This way, the kvm_irqfd system will > > not be ready. > > Since we can't have the initialization as kvm module init function > without forcing everyone to split modules, this is probably the best > way to handle this. > > Acked-by: Cornelia Huck <cornelia.huck@xxxxxxxxxx> Right. And please add a comment. Something like /* * kvm_arch_init makes sure there's at most one caller * for architectures that support multiple implementations, * like intel and amd on x86. * Must be called first to avoid creating conflicts * in case kvm is already setup for another implementation. */ > > > > This patch fix the following: > > > > BUG: unable to handle kernel NULL pointer dereference at (null) > > IP: [<ffffffff81c0721e>] _raw_spin_lock+0xe/0x30 > > PGD 0 > > Oops: 0002 [#1] SMP > > Modules linked in: vhost_net > > CPU 6 > > Pid: 4257, comm: qemu-system-x86 Not tainted 3.9.0-rc3+ #757 Dell Inc. OptiPlex 790/0V5HMK > > RIP: 0010:[<ffffffff81c0721e>] [<ffffffff81c0721e>] _raw_spin_lock+0xe/0x30 > > RSP: 0018:ffff880221721cc8 EFLAGS: 00010046 > > RAX: 0000000000000100 RBX: ffff88022dcc003f RCX: ffff880221734950 > > RDX: ffff8802208f6ca8 RSI: 000000007fffffff RDI: 0000000000000000 > > RBP: ffff880221721cc8 R08: 0000000000000002 R09: 0000000000000002 > > R10: 00007f7fd01087e0 R11: 0000000000000246 R12: ffff8802208f6ca8 > > R13: 0000000000000080 R14: ffff880223e2a900 R15: 0000000000000000 > > FS: 00007f7fd38488e0(0000) GS:ffff88022dcc0000(0000) knlGS:0000000000000000 > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > CR2: 0000000000000000 CR3: 000000022309f000 CR4: 00000000000427e0 > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 > > Process qemu-system-x86 (pid: 4257, threadinfo ffff880221720000, task ffff880222bd5640) > > Stack: > > ffff880221721d08 ffffffff810ac5c5 ffff88022431dc00 0000000000000086 > > 0000000000000080 ffff880223e2a900 ffff8802208f6ca8 0000000000000000 > > ffff880221721d48 ffffffff810ac8fe 0000000000000000 ffff880221734000 > > Call Trace: > > [<ffffffff810ac5c5>] __queue_work+0x45/0x2d0 > > [<ffffffff810ac8fe>] queue_work_on+0x8e/0xa0 > > [<ffffffff810ac949>] queue_work+0x19/0x20 > > [<ffffffff81009b6b>] irqfd_deactivate+0x4b/0x60 > > [<ffffffff8100a69d>] kvm_irqfd+0x39d/0x580 > > [<ffffffff81007a27>] kvm_vm_ioctl+0x207/0x5b0 > > [<ffffffff810c9545>] ? update_curr+0xf5/0x180 > > [<ffffffff811b66e8>] do_vfs_ioctl+0x98/0x550 > > [<ffffffff810c1f5e>] ? finish_task_switch+0x4e/0xe0 > > [<ffffffff81c054aa>] ? __schedule+0x2ea/0x710 > > [<ffffffff811b6bf7>] sys_ioctl+0x57/0x90 > > [<ffffffff8140ae9e>] ? trace_hardirqs_on_thunk+0x3a/0x3c > > [<ffffffff81c0f602>] system_call_fastpath+0x16/0x1b > > Code: c1 ea 08 38 c2 74 0f 66 0f 1f 44 00 00 f3 90 0f b6 03 38 c2 75 f7 48 83 c4 08 5b c9 c3 55 48 89 e5 66 66 66 66 90 b8 00 01 00 00 <f0> 66 0f c1 07 89 c2 66 c1 ea 08 38 c2 74 0c 0f 1f 00 f3 90 0f > > RIP [<ffffffff81c0721e>] _raw_spin_lock+0xe/0x30 > > RSP <ffff880221721cc8> > > CR2: 0000000000000000 > > ---[ end trace 13fb1e4b6e5ab21f ]--- > > > > Signed-off-by: Asias He <asias@xxxxxxxxxx> > > --- > > virt/kvm/kvm_main.c | 11 ++++++----- > > 1 file changed, 6 insertions(+), 5 deletions(-) > > > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > > index 8fd325a..3c8a992 100644 > > --- a/virt/kvm/kvm_main.c > > +++ b/virt/kvm/kvm_main.c > > @@ -3078,13 +3078,14 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align, > > int r; > > int cpu; > > > > - r = kvm_irqfd_init(); > > - if (r) > > - goto out_irqfd; > > r = kvm_arch_init(opaque); > > if (r) > > goto out_fail; > > > > + r = kvm_irqfd_init(); > > + if (r) > > + goto out_irqfd; > > + > > if (!zalloc_cpumask_var(&cpus_hardware_enabled, GFP_KERNEL)) { > > r = -ENOMEM; > > goto out_free_0; > > @@ -3159,10 +3160,10 @@ out_free_1: > > out_free_0a: > > free_cpumask_var(cpus_hardware_enabled); > > out_free_0: > > - kvm_arch_exit(); > > -out_fail: > > kvm_irqfd_exit(); > > out_irqfd: > > + kvm_arch_exit(); > > +out_fail: > > return r; > > } > > EXPORT_SYMBOL_GPL(kvm_init); -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html