From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Wei Liu <wei.liu2@citrix.com>, Andrew Jones <drjones@redhat.com>,
Keir Fraser <keir@xen.org>,
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>,
Olaf Hering <olaf@aepfle.de>, Tim Deegan <tim@xen.org>,
David Vrabel <david.vrabel@citrix.com>,
Jan Beulich <jbeulich@suse.com>,
xen-devel@lists.xenproject.org,
Daniel De Graaf <dgdegra@tycho.nsa.gov>
Subject: Re: [PATCH v8 08/11] xen: arch-specific hooks for domain_soft_reset()
Date: Tue, 14 Jul 2015 11:57:03 -0400 [thread overview]
Message-ID: <20150714155703.GA11081@l.oracle.com> (raw)
In-Reply-To: <87pp3uybw3.fsf@vitty.brq.redhat.com>
On Tue, Jul 14, 2015 at 05:52:44PM +0200, Vitaly Kuznetsov wrote:
> Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> writes:
>
> > On Tue, Jun 23, 2015 at 06:11:50PM +0200, Vitaly Kuznetsov wrote:
> >> ...
> >>
> >> +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 */
> >
> > Missing full stop. But perhaps we could explain what would be needed
> > for an PV guest to make it work (not as something for you to do
> > of course but an victim^H^H^Hvolunteer!).
> >
>
> Oh, I seriously doubt we'll ever be doing soft reset for classic PV. I
> don't see an easy way to preserve existent memory and without this soft
> reset is pointless. PVH (or PVHVM-without-dm) looks much more
> promising.
>
> >> + if ( !is_hvm_domain(d) )
> >> + return -EINVAL;
>
> I suggest we leave it here with the comment above and decide something
> later based on the chosen path for PVH.
>
> >> +
> >> + hvm_destroy_all_ioreq_servers(d);
> >> +
> >> + spin_lock(&d->event_lock);
> >> + for ( i = 1; i < d->nr_pirqs ; i ++ )
> >
> > Is pirq 0 special?
> >
>
> No, for some reason I though it is not a valid number for pirq. Will fix
> in v9.
>
> >> + if ( owner != d )
> >> + goto exit_put_page;
> >> +
> >> + mfn = page_to_mfn(page);
> >> + if ( !mfn_valid(mfn) )
> >> + {
> >> + printk(XENLOG_G_ERR "Dom%d's shared_info page points to invalid MFN\n",
> >> + d->domain_id);
> >
> > Would it be good to print out the PFN of the shared page to help narrow the cause?
> >
>
> I think this case is impossibe under normal circumstances and it's not
> clear to me how to get the PFN (did you mean GFN?) in such case.
Yes.
>
> shared_info is always allocated in arch_domain_create() from Xen heap
> and page_to_mfn() will never return INVALID_MFN here. In case we'll ever
> see this printed we'll have examine why this is not true anymore. This
> piece of code will have to be updated.
Ok, One way it could be if the guest decided to expunge this GFN fro
the guest (I think). Thought I am not sure why it would do such a thing :-)
>
> >> + if ( ret )
> >> + printk(XENLOG_G_ERR "Failed to add a page to replace"
> >> + " Dom%d's shared_info frame %lx\n", d->domain_id, gfn);
> >
> > Should we free the new_page in this case?
> >
>
> The new page is already in domain's page_list so we won't lose it on
> domain destroy but there is also no point in keeping it there if we
> failed to add it to physmap. Will free it in v9.
Thanks!
>
>
> --
> Vitaly
next prev parent reply other threads:[~2015-07-14 15:57 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-23 16:11 [PATCH v8 00/11] toolstack-assisted approach to PVHVM guest kexec Vitaly Kuznetsov
2015-06-23 16:11 ` [PATCH v8 01/11] xen: introduce SHUTDOWN_soft_reset shutdown reason Vitaly Kuznetsov
2015-07-07 20:44 ` Konrad Rzeszutek Wilk
2015-07-14 16:10 ` Ian Jackson
2015-07-15 8:42 ` Vitaly Kuznetsov
2015-06-23 16:11 ` [PATCH v8 02/11] libxl: support " Vitaly Kuznetsov
2015-07-07 20:47 ` Konrad Rzeszutek Wilk
2015-07-14 16:15 ` Ian Jackson
2015-07-15 8:43 ` Vitaly Kuznetsov
2015-06-23 16:11 ` [PATCH v8 03/11] xl: introduce enum domain_restart_type Vitaly Kuznetsov
2015-07-07 20:48 ` Konrad Rzeszutek Wilk
2015-06-23 16:11 ` [PATCH v8 04/11] xen: evtchn: make evtchn_reset() ready for soft reset Vitaly Kuznetsov
2015-07-10 16:20 ` Konrad Rzeszutek Wilk
2015-06-23 16:11 ` [PATCH v8 05/11] xen: grant_table: implement grant_table_warn_active_grants() Vitaly Kuznetsov
2015-07-10 16:24 ` Konrad Rzeszutek Wilk
2015-07-13 8:45 ` Jan Beulich
2015-07-13 9:08 ` Ian Campbell
2015-07-13 9:30 ` Jan Beulich
2015-07-13 9:35 ` Vitaly Kuznetsov
2015-07-13 13:44 ` Vitaly Kuznetsov
2015-07-13 14:24 ` Konrad Rzeszutek Wilk
2015-06-23 16:11 ` [PATCH v8 06/11] xen: Introduce XEN_DOMCTL_soft_reset Vitaly Kuznetsov
2015-07-10 16:30 ` Konrad Rzeszutek Wilk
2015-06-23 16:11 ` [PATCH v8 07/11] flask: DOMCTL_soft_reset support Vitaly Kuznetsov
2015-07-13 19:43 ` Daniel De Graaf
2015-06-23 16:11 ` [PATCH v8 08/11] xen: arch-specific hooks for domain_soft_reset() Vitaly Kuznetsov
2015-07-10 16:54 ` Konrad Rzeszutek Wilk
2015-07-14 15:52 ` Vitaly Kuznetsov
2015-07-14 15:57 ` Konrad Rzeszutek Wilk [this message]
2015-07-14 16:07 ` Vitaly Kuznetsov
2015-07-15 20:19 ` Julien Grall
2015-07-16 11:36 ` Vitaly Kuznetsov
2015-07-16 11:57 ` Julien Grall
2015-06-23 16:11 ` [PATCH v8 09/11] libxc: support XEN_DOMCTL_soft_reset operation Vitaly Kuznetsov
2015-06-25 13:52 ` Wei Liu
2015-07-10 16:55 ` Konrad Rzeszutek Wilk
2015-07-14 16:17 ` Ian Jackson
2015-06-23 16:11 ` [PATCH v8 10/11] libxc: add XC_DEVICE_MODEL_SAVE_FILE Vitaly Kuznetsov
2015-06-23 16:11 ` [PATCH v8 11/11] (lib)xl: soft reset support Vitaly Kuznetsov
2015-07-10 16:59 ` Konrad Rzeszutek Wilk
2015-07-14 16:19 ` Ian Jackson
2015-07-15 8:50 ` Vitaly Kuznetsov
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