Re: [Qemu-devel] [PATCH] hw/arm/virt: smbios: inform guest of kvm

[Andrew Jones]

On Thu, Sep 24, 2015 at 12:13:08PM +0200, Andrew Jones wrote:
> On Wed, Sep 23, 2015 at 08:43:39AM -0700, Peter Maydell wrote:
> > On 23 September 2015 at 07:18, Andrew Jones <address@hidden> wrote:
> > > ARM/AArch64 KVM guests don't have any way to identify
> > > themselves as KVM guests (x86 guests use a CPUID leaf). Now, we
> > > could discuss all sorts of reasons why guests shouldn't need to
> > > know that, but then there's always some case where it'd be
> > > nice... Anyway, now that we have SMBIOS tables in ARM guests,
> > > it's easy for the guest to know that it's a QEMU instance. This
> > > patch takes that one step further, also identifying KVM, when
> > > appropriate. Again, we could debate why generally nothing
> > > should care whether it's of type QEMU or QEMU/KVM, but again,
> > > sometimes it's nice to know...
> > 
> > This doesn't seem great to me, because it's ACPI/SMBIOS
> > specific. A mechanism that worked whether the guest was
> > booted via APCI or DT would seem preferable to me...
> 
> SMBIOS is populated on both ACPI and devicetree boots. We already
> have detection in virt-what and systemd-detect-virt for DT boots,
> although it only detects QEMU (it can't determine if KVM is used).
> That detection is DT-specific, and much more of a heuristic, it
> checks for the presence of the fw-cfg node in the DT. Actually, I'd
> like to patch those virt detection tools to try SMBIOS first (which,
> with this patch, could also give KVM info), and then fall back to
> trying the current DT-only, QEMU-only detection, before giving up.
>

Hi Peter,

Anymore thoughts on this?

Thanks,
drew