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[Qemu-devel] Re: [PATCH v2 14/17] kvm: x86: Introduce kvmclock device to
From: |
Jan Kiszka |
Subject: |
[Qemu-devel] Re: [PATCH v2 14/17] kvm: x86: Introduce kvmclock device to save/restore its state |
Date: |
Mon, 03 Jan 2011 17:30:27 +0100 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 |
Am 03.01.2011 17:04, Avi Kivity wrote:
> On 01/03/2011 10:33 AM, Jan Kiszka wrote:
>> From: Jan Kiszka<address@hidden>
>>
>> If kvmclock is used, which implies the kernel supports it, register a
>> kvmclock device with the sysbus. Its main purpose is to save and restore
>> the kernel state on migration, but this will also allow to visualize it
>> one day.
>>
>
> kvmclock is a per-cpu affair.
Nope, it's state (the one save/restored here) is per VM.
>
>>
>> @@ -534,6 +599,10 @@ int kvm_arch_init(int smp_cpus)
>> int ret;
>> struct utsname utsname;
>>
>> +#ifdef KVM_CAP_ADJUST_CLOCK
>> + sysbus_register_withprop(&kvmclock_info);
>> +#endif
>> +
>
> So this doesn't look right. I think we're fine with just migrating the
> MSRs, like we migrate anything else that has to do with the cpu.
>
The kvmclock state is not contained in any MSR. It's an independent
machine state that can be indirectly obtained via MSR access. Therefore,
qemu-kvm currently registers only one vmstate entry per machine, and
this patch just turns this into a clean device - because that's what
kvmclock is in the end, something like an HPET.
Jan
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- [Qemu-devel] [PATCH v2 00/17] [uq/master] Prepare for more qemu-kvm merging, Jan Kiszka, 2011/01/03
- [Qemu-devel] [PATCH v2 08/17] kvm: x86: Remove redundant mp_state initialization, Jan Kiszka, 2011/01/03
- [Qemu-devel] [PATCH v2 09/17] kvm: x86: Fix xcr0 reset mismerge, Jan Kiszka, 2011/01/03
- [Qemu-devel] [PATCH v2 01/17] kvm: Fix coding style violations, Jan Kiszka, 2011/01/03
- [Qemu-devel] [PATCH v2 05/17] x86: Optionally dump code bytes on cpu_dump_state, Jan Kiszka, 2011/01/03
- [Qemu-devel] [PATCH v2 14/17] kvm: x86: Introduce kvmclock device to save/restore its state, Jan Kiszka, 2011/01/03
- [Qemu-devel] Re: [PATCH v2 14/17] kvm: x86: Introduce kvmclock device to save/restore its state, Glauber Costa, 2011/01/03
- [Qemu-devel] [PATCH v2 07/17] kvm: x86: Prepare kvm_get_mp_state for in-kernel irqchip, Jan Kiszka, 2011/01/03
- [Qemu-devel] [PATCH v2 16/17] kvm: x86: Rework identity map and TSS setup for larger BIOS sizes, Jan Kiszka, 2011/01/03