Re: [PATCH kvm-kmod] adjust timekeeping compatibility code

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2014-10-02 12:12, Paolo Bonzini wrote:
> Il 01/10/2014 09:40, Jan Kiszka ha scritto:
>> [50764.182615] Call Trace:
>> [50764.182633]  [<ffffffffa12608bc>] vmx_vcpu_reset+0x20c/0x3b0 [kvm_intel]
>> [50764.182697]  [<ffffffffa12f503c>] kvm_arch_vcpu_setup+0x2c/0x50 [kvm]
>> [50764.182734]  [<ffffffffa12e24d4>] kvm_vm_ioctl_create_vcpu+0x84/0x1e0 [kvm]
>> [50764.182753]  [<ffffffffa12e29ab>] kvm_vm_ioctl+0x37b/0x520 [kvm]
>> [50764.182770]  [<ffffffff811e1685>] do_vfs_ioctl+0x75/0x2c0
>> [50764.182777]  [<ffffffff811e1971>] SyS_ioctl+0xa1/0xb0
>> [50764.182785]  [<ffffffff8167ef29>] system_call_fastpath+0x16/0x1b
>> [50764.182797]  [<00007f917b868d87>] 0x7f917b868d86
>> [50764.182800] Code: 00 e8 9c fe ff ff 48 63 45 fc 65 48 01 04 25 70 fd 00 00 c9 c3 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 55 48 89 e5 66 66 66 66 90 <48> f7 07 00 c0 00 00 75 14 f0 ff 4f 1c 74 08 c9 c3 66 0f 1f 44 
>> [50764.182828] RIP  [<ffffffff81168449>] put_page+0x9/0x30
>> [50764.182834]  RSP <ffff88022dd87d68>
>> [50764.182836] CR2: fffffffffffffffe
> 
> The call stack must be vmx_vcpu_reset ->
> kvm_vcpu_reload_apic_access_page -> put_page (tail call).
> 
> Is this with irqchip disabled?  If so, it's a KVM bug, it should be
> fixed like

Yes, that run was with irqchip off (due to IR emulation enabled). Will
give your fix a try once I can dare to crash my machine again. ;)

Thanks,
Jan

> 
>  void kvm_vcpu_reload_apic_access_page(struct kvm_vcpu *vcpu)
>  {
>  	struct page *page = NULL;
> 
> +	if (!irqchip_in_kernel(vcpu->kvm))
> +		return;
> +
>  	if (!kvm_x86_ops->set_apic_access_page_addr)
>  		return;
> 
> in x86.c, matching vm_need_virtualize_apic_accesses() in vmx.c.
> 
> Paolo
> 

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