Re: [Qemu-devel] [PATCH 1/3] s390/migration: Provide a cpu save for initial life migration work

[Alexander Graf <agraf@suse.de>]

On 11/21/2012 03:59 PM, Christian Borntraeger wrote:
> On 21/11/12 15:56, Alexander Graf wrote:
>> On 11/21/2012 03:46 PM, Christian Borntraeger wrote:
>>> This provides a simple cpu load and save function. With the recent
>>> addition of sync regs we have the crs,acrs, the prefix and the
>>> PSW already up to date. Lets also save the fpu via pre/post hooks.
>>>
>>> This patch also changes the license of machine.c to GPLv2 or later.
>>> (The old code was just empty glue code, so there is no need
>>> to go the "contributions after" way).
>>>
>>> Signed-off-by: Christian Borntraeger<borntraeger@de.ibm.com>
>>> ---
>>>    target-s390x/cpu.h     |    1 +
>>>    target-s390x/machine.c |  115 ++++++++++++++++++++++++++++++++++++++++++------
>>>    2 files changed, 103 insertions(+), 13 deletions(-)
>>>
>>> diff --git a/target-s390x/cpu.h b/target-s390x/cpu.h
>>> index 0f9a1f7..ba695dd 100644
>>> --- a/target-s390x/cpu.h
>>> +++ b/target-s390x/cpu.h
>>> @@ -27,6 +27,7 @@
>>>    #define ELF_MACHINE    EM_S390
>>>
>>>    #define CPUArchState struct CPUS390XState
>>> +#define CPU_SAVE_VERSION 1
>>>
>>>    #include "cpu-defs.h"
>>>    #define TARGET_PAGE_BITS 12
>>> diff --git a/target-s390x/machine.c b/target-s390x/machine.c
>>> index 3e79be6..02706fd 100644
>>> --- a/target-s390x/machine.c
>>> +++ b/target-s390x/machine.c
>>> @@ -2,29 +2,118 @@
>>>     * QEMU S390x machine definitions
>>>     *
>>>     * Copyright (c) 2009 Alexander Graf<agraf@suse.de>
>>> + * Copyright IBM Corp. 2012
>>>     *
>>> - * This library is free software; you can redistribute it and/or
>>> - * modify it under the terms of the GNU Lesser General Public
>>> - * License as published by the Free Software Foundation; either
>>> - * version 2 of the License, or (at your option) any later version.
>>> - *
>>> - * This library is distributed in the hope that it will be useful,
>>> - * but WITHOUT ANY WARRANTY; without even the implied warranty of
>>> - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>>> - * Lesser General Public License for more details.
>>> - *
>>> - * You should have received a copy of the GNU Lesser General Public
>>> - * License along with this library; if not, see<http://www.gnu.org/licenses/>.
>>> + * This work is licensed under the terms of the GNU GPL, version 2 or (at your
>>> + * option) any later version.  See the COPYING file in the top-level directory.
>>>     */
>>>
>>>    #include "hw/hw.h"
>>>    #include "hw/boards.h"
>>> +#include "cpu.h"
>>> +#include "kvm.h"
>>> +
>>> +#if defined CONFIG_KVM
>>> +static void cpu_pre_save(void *opaque)
>>> +{
>>> +    CPUS390XState *env = opaque;
>>> +    struct kvm_fpu fpu;
>>> +    int i, r;
>>> +
>>> +    if (!kvm_enabled()) {
>>> +        return;
>>> +    }
>>> +
>>> +    r = kvm_vcpu_ioctl(env, KVM_GET_FPU,&fpu);
>>> +    assert(r == 0);
>>> +    for (i = 0; i<   16; i++) {
>>> +        env->fregs[i].ll = fpu.fprs[i];
>>> +    }
>>> +    env->fpc = fpu.fpc;
>>> +}
>>> +
>>> +static int cpu_post_load(void *opaque, int version_id)
>>> +{
>>> +    CPUS390XState *env = opaque;
>>> +    struct kvm_fpu fpu;
>>> +    int i, r;
>>> +
>>> +    if (!kvm_enabled()) {
>>> +        return 0;
>>> +    }
>>> +
>>> +    for (i = 0; i<   16; i++) {
>>> +        fpu.fprs[i] = env->fregs[i].ll;
>>> +    }
>>> +    fpu.fpc = env->fpc;
>>> +
>>> +    r = kvm_vcpu_ioctl(env, KVM_SET_FPU,&fpu);
>>> +    assert(r == 0);
>>> +
>>> +    return 0;
>>> +}
>> The kvm register sync needs to happen in the kvm register sync function :)
> That would eliminate the whole purpose of sync regs and forces us to have an
> expensive ioctl on lots of exits (again). I would prefer to sync the registers
> that we never need in qemu just here.

That's why the register sync has different stages.


Alex