Re: [Xen-devel] [PATCH 3/3] pvh/dom0: whitelist PVH Dom0 ACPI tables

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Tue, Feb 13, 2018 at 06:41:14AM -0700, Jan Beulich wrote:
> >>> On 13.02.18 at 12:27, <roger.pau@xxxxxxxxxx> wrote:
> > On Tue, Feb 13, 2018 at 04:04:17AM -0700, Jan Beulich wrote:
> >> >>> On 13.02.18 at 10:59, <roger.pau@xxxxxxxxxx> wrote:
> >> > On Tue, Feb 13, 2018 at 02:29:08AM -0700, Jan Beulich wrote:
> >> >> >>> On 08.02.18 at 13:25, <roger.pau@xxxxxxxxxx> wrote:
> >> >> > Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> >> >> 
> >> >> A change like this should not come without description, providing a
> >> >> reason for the change. Otherwise how will someone wanting to
> >> >> understand the change in a couple of years actually be able to
> >> >> make any sense of it. This is in particular because I continue to be
> >> >> not fully convinced that white listing is appropriate in the Dom0
> >> >> case (and for the record I'm similarly unconvinced that black listing
> >> >> is the best choice, yet obviously we need to pick on of the two).
> >> > 
> >> > I'm sorry, I thought we agreed at the summit to convert this to
> >> > whitelisting because it was likely better to simply not expose unknown
> >> > ACPI tables to guests.
> >> 
> >> "to guests" != "to Dom0".
> >> 
> >> > I guess the commit message could be something like:
> >> > 
> >> > "The following list of whitelisted APIC tables are either known to work
> >> > or don't require any resources to be mapped in either the IO or the
> >> > memory space.
> >> 
> >> Even if the white listing vs black listing question wasn't still
> >> undecided, I think we should revert the patch in favor of one
> >> with a description. The one above might be fine with "ACPI" in
> >> place of "APIC" as far as tables actively white listed are
> >> concerned, but then it still remains open why certain tables
> >> haven't been included. I'm in particular worried about various
> >> APEI related tables, but invisibility of e.g. an IBFT could also
> >> lead to boot problems.
> > 
> > Regarding APEI I think ERST, EINJ and HEST could be passed through,
> > BERT however requires that the BOOT Error Region is mapped into Dom0
> > p2m.
> > 
> > Since PVH Dom0 creation still ends up in a panic, I see no problem in
> > adding those in follow up patches.
> > 
> > IBFT also looks safe to pass through.
> 
> But you realize I've named only the few that came to mind
> immediately?

Sure, what I have in this patch is just the minimal set (plus a few
others that seem completely fine) needed in order to boot on my two
test boxes.

I know we will certainly have to expand this, but I see no issue in
adding them as we go, the more that this is all still unused.

Thanks, Roger.

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