Re: libxl - b_info.{acpi,apic} behaves differently than b_info.u.hvm.{acpi,apic}

[Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>]

On Thu, Sep 10, 2020 at 12:58:57PM +0200, Marek Marczykowski-Górecki wrote:
> On Thu, Sep 10, 2020 at 12:41:04PM +0200, Roger Pau Monné wrote:
> > Adding toolstack maintainers.
> > 
> > On Thu, Sep 10, 2020 at 12:29:21PM +0200, Marek Marczykowski-Górecki wrote:
> > > On Thu, Sep 10, 2020 at 10:51:48AM +0200, Roger Pau Monné wrote:
> > > > On Thu, Sep 10, 2020 at 05:57:23AM +0200, Marek Marczykowski-Górecki 
> > > > wrote:
> > > > > Hi,
> > > > > 
> > > > > After updating from Xen 4.13 to Xen 4.14 I have troubles starting any
> > > > > HVM: just after hvmloader saying "Invoking SeaBIOS" I get "(XEN) MMIO
> > > > > emulation failed (1): d29v0 32bit @ 0008:fffeedf d -> "
> > > > > 
> > > > > I come to a situation where seemingly the same domU started via xl
> > > > > works, while when started via libvirt it crashes. This seems to be
> > > > > related to xl setting b_info.{acpi,apic}, while libvirt setting
> > > > > b_info.u.hvm.{acpi,apic}. Modifying libvirt to use the former fixes 
> > > > > the
> > > > > issue.
> > > > 
> > > > Could you print the values of the involved fields at the end of
> > > > libxl__domain_build_info_setdefault in both cases?
> > > > 
> > > > I'm not able to spot what changed between 4.13 and 4.14 that could
> > > > alter the behavior, but knowing the values at that point might make
> > > > it easier.
> > > 
> > > Sure, will do.
> > > It may be also something else: maybe it acpi/apic settings were broken
> > > before, but did not results in a domU crash this way.
> > > FWIW when looking into /var/lib/xen/*-libxl-json I clearly see
> > > difference between b_info.{acpi,apic} and b_info.u.hvm.{acpi,apic}.
> > 
> > I think libxl__domain_build_info_setdefault should check whether
> > b_info.u.hvm.{acpi,apic} is set and copy those into b_info.{acpi,apic}
> > if those are not set?
> 
> Looking at libxl__domain_build_info_setdefault this is not the case.
> Instead there is libxl__acpi_defbool_val which looks at both.
> Oh, and there is no similar thing for apic -> b_info.u.hvm.apic is
> ignored!
> 
> > Toolstack people is more likely to have an opinion here, or to help
> > debug the issue.

Ok, The crash reported initially was caused by a different thing: using
seabios.bin instead of seabios-256k.bin (should that really cause the
crash? shouldn't 128k seabios build work too?). But in any case, I think
the b_info.u.hvm.{acpi,apic} is also not in a good shape.

-- 
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?

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