On Tue, Aug 11, 2015 at 12:11 PM, Pavel Fedin <p.fedin@xxxxxxxxxxx> wrote:
> Hello!
>
>> I have prototyped Live migration with GICv3.
>
> This is interesting of course, i will need this for my project too and i was also going to take a look at this later.
>
>> For this I have made following changes
>>
>> 1) Save and Restore of GICv3 registers in QEMU.
>> - For GICv2, QEMU is saving/restoring GICD, GICC registers. For GICv3,
>> we have to save/restore GICD, GICR and ICC registers.
>> However ICC registers are system registers which cannot be
>> accessed @ EL0 level (SRE=1). So these ICC registers should be
>> accessed as mmio registers by QEMU, for this we have to add ioctl to
>> access ICC @ EL1 level similar to GICC registers of GICv2.
>
> Sorry, your description is a bit fuzzy. What ioctl's did you have to add and why?
> The kernel already has KVM_GET_ONE_REG and KVM_SET_ONE_REG ioctl's. And they can be used to access anything inside the VM, including system registers. I believe you would need only to implement handlers for GICv3 registers.
I mean CPU interface registers GICC* defined for vgicv2 under
"vgic_cpu_ranges[]" in
virt/kvm/arm/vgic-v2-emul.c needs to be saved and restored for vgicv3 as well.
So to access vgic_cpu_ranges[] for vgicv3, we need to register device
for CPU registers space
similar to gicv2 in QEMU for gicv3.
-----------------------------------------------------------------------------------------
memory_region_init_reservation(&s->cpuiomem[0], OBJECT(s),
"kvm-gic_cpu", 0x1000);
sysbus_init_mmio(sbd, &s->cpuiomem[0]);
kvm_arm_register_device(&s->cpuiomem[0],
(KVM_ARM_DEVICE_VGIC_V3 << KVM_ARM_DEVICE_ID_SHIFT)
| KVM_VGIC_V3_ADDR_TYPE_CPU,
KVM_DEV_ARM_VGIC_GRP_ADDR,
KVM_VGIC_V3_ADDR_TYPE_CPU,
s->dev_fd);
-------------------------------------------------------------------------------------------
Anyway, I will send RFC patches.
>
>> Please provide your initial feedback.
>
> Would be nice to take a look at patches.
>
>> I am attending KVM-forum next week @ Seattle. We can discuss there as well.
>
> I would love to go there, and my company wanted to send me there. But it appears to be extremely difficult for a tech specialist from Russia to get a US visa. They are still considering me and the time is running out, so i'm unlikely to attend, unfortunately.
>
> Kind regards,
> Pavel Fedin
> Expert Engineer
> Samsung Electronics Research center Russia
>
>
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