linux-kernel - Re: [Xen-devel] [PATCH v2] xen, kdump: handle pv domain in paddr_vmcoreinfo

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Date:   Tue, 11 Apr 2017 19:20:08 +0200
From:   Daniel Kiper <daniel.kiper@...cle.com>
To:     Petr Tesarik <ptesarik@...e.com>
Cc:     Juergen Gross <jgross@...e.com>,
        Daniel Kiper <dkiper@...-space.pl>,
        linux-kernel@...r.kernel.org, xen-devel@...ts.xenproject.org,
        boris.ostrovsky@...cle.com, eric.devolder@...cle.com,
        konrad.wilk@...cle.com, andrew.cooper3@...rix.com
Subject: Re: [Xen-devel] [PATCH v2] xen, kdump: handle pv domain in
 paddr_vmcoreinfo_note()

On Tue, Apr 11, 2017 at 04:59:16PM +0200, Petr Tesarik wrote:
> On Tue, 11 Apr 2017 15:00:58 +0200
> Daniel Kiper <daniel.kiper@...cle.com> wrote:
>
> > On Tue, Apr 11, 2017 at 02:45:43PM +0200, Juergen Gross wrote:
> > > On 03/04/17 14:42, Daniel Kiper wrote:
> > > > On Fri, Mar 31, 2017 at 12:14:38PM +0200, Juergen Gross wrote:
> > > >> For kdump to work correctly it needs the physical address of
> > > >> vmcoreinfo_note. When running as dom0 this means the virtual address
> > > >> has to be translated to the related machine address.
> > > >>
> > > >> paddr_vmcoreinfo_note() is meant to do the translation via
> > > >> __pa_symbol() only, but being attributed "weak" it can be replaced
> > > >> easily in Xen case.
> > > >>
> > > >> Signed-off-by: Juergen Gross <jgross@...e.com>
> > > >
> > > > Have you tested this patch with latest crash tool? Do dom0 and Xen
> > > > hypervisor analysis work without any issue (at least basic commands
> > > > like dmesg, bt, ps, etc.)? If yes for both you can add:
> > > >
> > > > Reviewed-by: Daniel Kiper <daniel.kiper@...cle.com>
> > >
> > > So can I add your R-b: now?
> >
> > My R-b is still valid. Though, let's wait for Petr's Tested-by. He
> > did makedumpfile tests but I asked him to do crash tool tests too.
> > I think it is important.
>
> Tested-by: Petr Tesarik <ptesarik@...e.com>
>
> I copied the complete /proc/vmcore to a directory on disk. Exactly
> as expected, crash works both without the patch and with the patch, as
> it does not use VMCOREINFO at all (instead, crash obtains the
> information from kernel debuginfo directly).

Thanks for doing the tests. I suppose that you have tested HVM guests.
IIRC, PV guests are not supported by crash right now due to p2m VMA
mapping. At least it was an issue some time ago. Is it still valid?
Anyway, one guy in Oracle works on fix for that issue and I do review.
We are going to post it in 2-3 weeks.

Juergen, I do not have any objections any longer. You can go ahead.
Ahhh... I see. You have posted v3. Good!

Daniel