On Wed, Feb 13, 2008 at 04:24:53PM +0100, Jiri Kosina wrote:
> On Wed, 13 Feb 2008, Zdenek Kabelac wrote:
>
> > I get this bug in my log whenever I start qemu-kvm - I do not use kqemu
> > module - so it's with plain kernel modules. If more details are needed -
> > just ask. (Cpu; C2D)
> > BUG: sleeping function called from invalid context at kernel/rwsem.c:48
> > in_atomic():1, irqs_disabled():0
> > INFO: lockdep is turned off.
> > Pid: 26600, comm: qemu-kvm Not tainted 2.6.25-rc1 #29
>
> This has been obviously caused by Marcelo's (added to CC) commit
> 10589a4699b, which added down_write(mmap_sem) to alloc_apic_access_page(),
> which is called with preempt disabled from vmx_create_vcpu().
alloc_apic_access_page() called mutex_lock, so the warning would trigger
before that change.
I think it's fine to allocate the APIC page after put_cpu(), since no vcpu
state is required.
Avi?
--- linux-2.6.orig/arch/x86/kvm/vmx.c
+++ linux-2.6/arch/x86/kvm/vmx.c
@@ -1601,9 +1601,6 @@ static int vmx_vcpu_setup(struct vcpu_vm
vmcs_writel(CR0_GUEST_HOST_MASK, ~0UL);
vmcs_writel(CR4_GUEST_HOST_MASK, KVM_GUEST_CR4_MASK);
- if (vm_need_virtualize_apic_accesses(vmx->vcpu.kvm))
- if (alloc_apic_access_page(vmx->vcpu.kvm) != 0)
- return -ENOMEM;
return 0;
}
@@ -2533,6 +2530,9 @@ static struct kvm_vcpu *vmx_create_vcpu(
put_cpu();
if (err)
goto free_vmcs;
+ if (vm_need_virtualize_apic_accesses(kvm))
+ if (alloc_apic_access_page(kvm) != 0)
+ goto free_vmcs;
return &vmx->vcpu;
--
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