From mboxrd@z Thu Jan  1 00:00:00 1970
From: Vitaly Kuznetsov <vkuznets@redhat.com>
Subject: Re: [PATCH v9 08/11] xen: arch-specific hooks for
	domain_soft_reset()
Date: Fri, 24 Jul 2015 14:41:17 +0200
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To: Jan Beulich <JBeulich@suse.com>
Cc: Olaf Hering <olaf@aepfle.de>, Wei Liu <wei.liu2@citrix.com>, Ian Campbell <ian.campbell@citrix.com>, Stefano Stabellini <stefano.stabellini@eu.citrix.com>, Andrew Cooper <andrew.cooper3@citrix.com>, Julien Grall <julien.grall@linaro.org>, Ian Jackson <ian.jackson@eu.citrix.com>, Andrew Jones <drjones@redhat.com>, Tim Deegan <tim@xen.org>, David Vrabel <david.vrabel@citrix.com>, xen-devel@lists.xenproject.org, Daniel De Graaf <dgdegra@tycho.nsa.gov>, Keir Fraser <keir@xen.org>
List-Id: xen-devel@lists.xenproject.org

"Jan Beulich" <JBeulich@suse.com> writes:

>>>> On 16.07.15 at 18:27, <vkuznets@redhat.com> wrote:
>> --- a/xen/arch/x86/domain.c
>> +++ b/xen/arch/x86/domain.c
>> @@ -704,6 +704,90 @@ void arch_domain_unpause(struct domain *d)
>>          viridian_time_ref_count_thaw(d);
>>  }
>>  
>> +int arch_domain_soft_reset(struct domain *d)
>> +{
>> +    struct page_info *page = virt_to_page(d->shared_info), *new_page;
>> +    int ret = 0;
>> +    struct domain *owner;
>> +    unsigned long mfn, mfn_new, gfn;
>> +    p2m_type_t p2mt;
>> +    unsigned int i;
>> +
>> +    /* Soft reset is supported for HVM domains only. */
>> +    if ( !is_hvm_domain(d) )
>> +        return -EINVAL;
>
> This suggests that the whole function may better go somewhere in
> hvm/.
>
> And is this intentionally excluding PVH?
>

Not really.

As far as I understand the descision is to go for "HVM without dm" way
for PVH in future? In that case, isn't is_hvm_domain() supposed to
return true for it? I hope the selected approach to kexec should "just
work" for such PVH guests.

>...
>> --- a/xen/common/domain.c
>> +++ b/xen/common/domain.c
>> @@ -1035,6 +1035,10 @@ int domain_soft_reset(struct domain *d)
>>      for_each_vcpu ( d, v )
>>          unmap_vcpu_info(v);
>>  
>> +    rc = arch_domain_soft_reset(d);
>> +    if (rc)
>> +        return rc;
>
> I don't think this can be done this late, or else you'd need to have
> a way to undo everything you've done earlier in the function. This
> of course also applies to what's being done inside the function. Or
> if undoing is - as it looks like - rather hard, perhaps the domain
> would better be crashed than left in an inconsistent state?

Crashing the domain seems reasonable.

-- 
  Vitaly