[Qemu-devel] [PATCH for-2.12 0/2] i386/hyperv: fully control Hyper-V features in CPUID

[Roman Kagan <rkagan@virtuozzo.com>]

In order to guarantee compatibility on migration, QEMU should have
complete control over the features it announces to the guest via CPUID.

However, a number of Hyper-V-related features happen to depend on the
support in the underlying KVM, with no regard to QEMU configuration.

Make QEMU regain control over what Hyper-V features it announces to the
guest.

Note: the patches are also being proposed for stable-2.11, even though
one of them introduces a new cpu property.  This is done to minimize the
number of published QEMU releases where the behavior of the features is
unpredictable, with potentially fatal consequences for the guest.

Note #2: there are other problems in the surrounding code, like ugly
error reporting or inconsistent population of MSRs.  I think this can be
put off to post-2.12.

Roman Kagan (2):
  i386/hyperv: add hv-frequencies cpu property
  i386/hyperv: error out if features requested but unsupported

Cc: qemu-stable@nongnu.org

 target/i386/cpu.h |  1 +
 target/i386/cpu.c |  1 +
 target/i386/kvm.c | 37 +++++++++++++++++++++++++++++--------
 3 files changed, 31 insertions(+), 8 deletions(-)

-- 
2.14.3