linux-kernel - [PATCH v2 0/9] xen/x86: PVH Dom0 fixes and fallout adjustments

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Message-ID: <9a26d4ff-80a1-e0c1-f528-31a8568d41f7@suse.com>
Date:   Thu, 30 Sep 2021 14:12:31 +0200
From:   Jan Beulich <jbeulich@...e.com>
To:     Juergen Gross <jgross@...e.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>
Cc:     Stefano Stabellini <sstabellini@...nel.org>,
        lkml <linux-kernel@...r.kernel.org>,
        Roger Pau Monné <roger.pau@...rix.com>,
        "xen-devel@...ts.xenproject.org" <xen-devel@...ts.xenproject.org>
Subject: [PATCH v2 0/9] xen/x86: PVH Dom0 fixes and fallout adjustments

In order to try to debug hypervisor side breakage from XSA-378 I found
myself urged to finally give PVH Dom0 a try. Sadly things didn't work
quite as expected. In the course of investigating these issues I actually
spotted one piece of PV Dom0 breakage as well, a fix for which is also
included here.

There are one immediate remaining issues: Dom0, unlike in the PV case,
cannot access the screen (to use as a console) when in a non-default
mode (i.e. not 80x25 text), as the necessary information (in particular
about VESA-bases LFB modes) is not communicated. On the hypervisor side
this looks like deliberate behavior, but it is unclear to me what the
intentions were towards an alternative model. (X may be able to access
the screen depending on whether it has a suitable driver besides the
presently unusable /dev/fb<N> based one.)

v2 merely addresses small review comments in patches 7 and 9 (see there).

1: xen/x86: prevent PVH type from getting clobbered
2: xen/x86: allow PVH Dom0 without XEN_PV=y
3: xen/x86: make "earlyprintk=xen" work better for PVH Dom0
4: xen/x86: allow "earlyprintk=xen" to work for PV Dom0
5: xen/x86: make "earlyprintk=xen" work for HVM/PVH DomU
6: xen/x86: generalize preferred console model from PV to PVH Dom0
7: xen/x86: hook up xen_banner() also for PVH 
8: x86/PVH: adjust function/data placement
9: xen/x86: adjust data placement

Jan