Re: [PATCH v6 05/16] target-i386: Use Hypervisor level in -machine pc, accel=kvm.

Marcelo Tosatti
2012-10-09T18:47:53Z

On Tue, Oct 09, 2012 at 03:27:26PM -0300, Marcelo Tosatti wrote:
> On Tue, Oct 09, 2012 at 02:18:05PM -0300, Marcelo Tosatti wrote:
> > On Mon, Sep 24, 2012 at 10:32:07AM -0400, Don Slutz wrote:
> > > Also known as Paravirtualization level.
> > >
> > > This change is based on:
> > >
> > > Microsoft Hypervisor CPUID Leaves:
> > > http://msdn.microsoft.com/en-us/library/windows/hardware/ff542428%28v=vs.85%29.aspx
> > >
> > > Linux kernel change starts with:
> > > http://fixunix.com/kernel/538707-use-cpuid-communicate-hypervisor.html
> > > Also:
> > > http://lkml.indiana.edu/hypermail/linux/kernel/1205.0/00100.html
> > >
> > > VMware documention on CPUIDs (Mechanisms to determine if software is
> > > running in a VMware virtual machine):
> > > http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1009458
> > >
> > > QEMU knows this is KVM_CPUID_SIGNATURE (0x40000000).
> > >
> > > Signed-off-by: Don Slutz <Don@CloudSwitch.com>
> > > ---
> > > target-i386/kvm.c | 4 ++--
> > > 1 files changed, 2 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/target-i386/kvm.c b/target-i386/kvm.c
> > > index 895d848..8462c75 100644
> > > --- a/target-i386/kvm.c
> > > +++ b/target-i386/kvm.c
> > > @@ -389,12 +389,12 @@ int kvm_arch_init_vcpu(CPUX86State *env)
> > > c = &cpuid_data.entries[cpuid_i++];
> > > memset(c, 0, sizeof(*c));
> > > c->function = KVM_CPUID_SIGNATURE
> > > - if (!hyperv_enabled()) {
> > > + if (!env->cpuid_hv_level_set) {
> > > memcpy(signature, "KVMKVMKVM\0\0\0", 12);
> > > c->eax = 0;
> > > } else {
> > > memcpy(signature, "Microsoft Hv", 12);
> > > - c->eax = HYPERV_CPUID_MIN;
> > > + c->eax = env->cpuid_hv_level;
> >
> > This breaks hyperv_enabled() checks.
> >
> > Don, are you certain it is worthwhile to make this configurable?
> > Can you explain why, under your scenario, it is worthwhile?
> >
> > Because these are separate problems:
> >
> > - "Fake" VMWare hypervisor (which seems to be your main goal).
> > - Make CPUID HV leafs configurable via command line.
>
> Err, meant via properties. Point is, why have VMWare CPUID
> configuration as data, if there are reasons to believe code
> is a better fit (code as in current Hyper-V implementation).

Nevermind, its the right thing to do. Just separate the patchset
please:

1) Create object properties.
2) Export VMWare CPUID via properties.
3) Convert Hyper-V.

Be careful to make sure Hyper-V's current options are functional
in 3).