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

[Don Slutz]

On 10/09/12 15:11, Marcelo Tosatti wrote:
> On Tue, Oct 09, 2012 at 03:09:17PM -0400, Don Slutz wrote:
> > On 10/09/12 14:47, Marcelo Tosatti wrote:
> > > 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 <address@hidden>
> > > > > > ---
> > > > > >   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).
> > Did you mean 3 patch sets (or more)? Or just a different order?
> >     -Don Slutz
> Different order. Patches should be logically related (think of what
> information the reviewer needs). Please write changelogs for
> every patch.
Using this order causes support for Hyper-V to stop working in the 
middle of the patch set.  How about this order:
1) Create object properties.
2) Convert Hyper-V to set the new properties.
3) Change kvm.c to use the new properties.
4) Export VMWare CPUID via properties.

5) Change accel=tcg to use the new properties.

   -Don Slutz