Re: [PATCH for-4.7] libxl/save: set domain_suspend_state->domid in do_domain_soft_reset()

From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: Wei Liu <wei.liu2@citrix.com>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>,
	Ian Jackson <ian.jackson@eu.citrix.com>,
	Wen Congyang <wency@cn.fujitsu.com>,
	xen-devel@lists.xen.org
Subject: Re: [PATCH for-4.7] libxl/save: set domain_suspend_state->domid in do_domain_soft_reset()
Date: Mon, 11 Apr 2016 14:53:21 +0200	[thread overview]
Message-ID: <87zit0e27y.fsf@vitty.brq.redhat.com> (raw)
In-Reply-To: <20160411123614.GI1346@citrix.com> (Wei Liu's message of "Mon, 11 Apr 2016 13:36:14 +0100")

Wei Liu <wei.liu2@citrix.com> writes:

> Sorry for breaking it!
>

Np!

> On Mon, Apr 11, 2016 at 02:20:04PM +0200, Vitaly Kuznetsov wrote:
>> c/s d5c693d "libxl/save: Refactor libxl__domain_suspend_state" broke soft
>> reset as libxl__domain_suspend_device_model() now fails when domid in not set
>> in libxl__domain_suspend_state.
>> 
>> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
>
> Acked-by: Wei Liu <wei.liu2@citrix.com>
>
> What sort of arrangement is needed to get this tested? Any specific
> kernel version etc?
>

You need a kernel with the following:

commit 0b34a166f291d255755be46e43ed5497cdd194f2
Author: Vitaly Kuznetsov <vkuznets@redhat.com>
Date:   Fri Sep 25 11:59:52 2015 +0200

    x86/xen: Support kexec/kdump in HVM guests by doing a soft reset

It is included in upstream kernels starting from 4.5 and a number of
stable kernels.

To smoke test the feature your linux kernel should have KEXEC, in my
.config I see:

CONFIG_KEXEC_CORE=y
CONFIG_KEXEC=y
CONFIG_KEXEC_FILE=y
# CONFIG_KEXEC_VERIFY_SIG is not set
CONFIG_KEXEC_JUMP=y

and then you can simply do:
# kexec -f --reuse-cmdline --initrd /boot/initramfs-`uname -r`.img /boot/vmlinuz-`uname -r`

to experience 'soft reset'. You can also try to do kdump arming for your
kernel and crashing it (with e.g. 'echo c > /proc/sysrq-trigger').

>> ---
>>  tools/libxl/libxl_create.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>> 
>> diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
>> index f1028bc..f8d5e36 100644
>> --- a/tools/libxl/libxl_create.c
>> +++ b/tools/libxl/libxl_create.c
>> @@ -1700,7 +1700,7 @@ static int do_domain_soft_reset(libxl_ctx *ctx,
>>      free(xs_console_mfn);
>>  
>>      dss->ao = ao;
>> -    dss->domid = domid_soft_reset;
>> +    dss->domid = dss->dsps.domid = domid_soft_reset;
>>      dss->dsps.dm_savefile = GCSPRINTF(LIBXL_DEVICE_MODEL_SAVE_FILE".%d",
>>                                        domid_soft_reset);
>>  
>> -- 
>> 2.5.5
>> 

-- 
  Vitaly

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