Re: [RFC PATCH 00/45] KVM: arm/arm64: Rework virtual GIC emulation

[Vladimir Murzin <vladimir.murzin@arm.com>]

On 30/03/16 12:42, Vladimir Murzin wrote:
> On 29/03/16 14:12, Vladimir Murzin wrote:
>> Hi Andre,
>>
>> On 25/03/16 02:04, Andre Przywara wrote:
>>> Please have a look at the series, review it and give the code some
>>> serious testing (and possibly debugging). All feedback is appreciated.
>>
>> I see that with the new vgic implementation kvmtool starts throwing:
>>
>> kvm [1273]: Unable to register VGICv3 redist MMIO regions
>>
> 
> It comes from kvm_io_bus_register_dev()
> 
> if (bus->dev_count - bus->ioeventfd_count > NR_IOBUS_DEVS - 1)
> 	return -ENOSPC;
> 
> with bus->dev_count being 1000
> 
> [<ffffffc00009f93c>] kvm_io_bus_register_dev+0x130/0x148
> [<ffffffc0000ad274>] kvm_vgic_register_mmio_region+0xac/0xdc
> [<ffffffc0000ad4d4>] vgic_register_redist_regions+0xb8/0x158
> [<ffffffc0000abb90>] vgic_v3_map_resources+0x5c/0xf0
> [<ffffffc0000aae04>] kvm_vgic_map_resources+0x40/0x84
> [<ffffffc0000a23d0>] kvm_arch_vcpu_ioctl_run+0x3f0/0x400
> [<ffffffc00009d484>] kvm_vcpu_ioctl+0x2d4/0x6ec
> [<ffffffc0001c4eec>] do_vfs_ioctl+0xb4/0x760
> [<ffffffc0001c561c>] SyS_ioctl+0x84/0x98
> [<ffffffc000085d30>] el0_svc_naked+0x24/0x28
> 

and one more thing I've forgotten to mention... something odd happens on
destroy path

INFO: task kvm-vcpu-0:1123 blocked for more than 120 seconds.
      Tainted: G        W       4.5.0-rc6+ #432
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kvm-vcpu-0      D ffffffc000086bcc     0  1123   1114 0x00000008
Call trace:
[<ffffffc000086bcc>] __switch_to+0x90/0xa4
[<ffffffc0006c4390>] __schedule+0x188/0x59c
[<ffffffc0006c47e0>] schedule+0x3c/0xa0
[<ffffffc0006c4bf4>] schedule_preempt_disabled+0x20/0x38
[<ffffffc0006c618c>] __mutex_lock_slowpath+0xc4/0x148
[<ffffffc0006c6254>] mutex_lock+0x44/0x5c
[<ffffffc0000aacb8>] kvm_vgic_destroy+0x20/0xb0
[<ffffffc0000abbdc>] vgic_v3_map_resources+0xa8/0xf0
[<ffffffc0000aae04>] kvm_vgic_map_resources+0x40/0x84
[<ffffffc0000a23d0>] kvm_arch_vcpu_ioctl_run+0x3f0/0x400
[<ffffffc00009d484>] kvm_vcpu_ioctl+0x2d4/0x6ec
[<ffffffc0001c4eec>] do_vfs_ioctl+0xb4/0x760
[<ffffffc0001c561c>] SyS_ioctl+0x84/0x98
[<ffffffc000085d30>] el0_svc_naked+0x24/0x28

Vladimir

> Hope this helps...
> Vladimir
> 
>> for --cpus 58 and above, where with the old vgic it is quite happy with
>> up to 255 cpus.
>>
>> Cheers
>> Vladimir
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>>
>>
> 
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