Recent CPU models were specified using invalid vendor element
<vendor>NAME</vendor>, which was silently ignored due to a bug in the
code which was parsing it.

This enables support for nested SVM using the regular CPU
model/features block. If the CPU model or features include
'svm', then the '-enable-nesting' flag will be added to the
QEMU command line. Latest out of tree patches for nested
'vmx', no longer require the '-enable-nesting' flag. They
instead just look at the cpu features. Several of the models
already include svm support, but QEMU was just masking out
the svm bit silently. So this will enable SVM on such
models

* src/qemu/qemu_conf.h: flag for -enable-nesting
* src/qemu/qemu_conf.c: Use -enable-nesting if VMX or SVM are in
  the CPUID
* src/cpu/cpu.h, src/cpu/cpu.c: API to check for a named feature
* src/cpu/cpu_x86.c: x86 impl of feature check
* src/libvirt_private.syms: Add cpuHasFeature
* src/qemuhelptest.c: Add nesting flag where required

This patch fixes a couple of complaints from valgrind when tickling libvirtd with SIGHUP.

The first two files contain fixes for memory leaks. The 3rd one initializes an uninitialized variable. The 4th one is another memory leak.

When a CPU to be compared with host CPU describes a host CPU instead of
a guest CPU, the result is incorrect. This is because instead of
treating additional features in host CPU description as required, they
were treated as if they were mentioned with all possible policies at the
same time.

By specifying <vendor> element in CPU requirements a guest can be
restricted to run only on CPUs by a given vendor. Host CPU vendor is
also specified in capabilities XML.

The vendor is checked when migrating a guest but it's not forced, i.e.,
guests configured without <vendor> element can be freely migrated.

In case the set of CPUs has no features in common, report incompatible
CPUs instead of returning the simplest CPU model with all features
disabled.

All features in the baseline CPU definition were always created with
policy='require' even though an arch driver returned them with different
policy settings.

* src/cpu/cpu_x86.c (x86ModelHasFeature): Do not dereference the pointer
returned by x86cpuidFind without first ensuring it is non-NULL.

Adds ability to provide a preferred CPU model for CPUID data decoding.
Such model would be considered as the best possible model (if it's
supported by hypervisor) regardless on number of features which have to
be added or removed for describing required CPU.

So far, when CPUID data were converted into CPU model and features, the
features can only be added to the model. As a result, when a guest asked
for something like "qemu64,-svm" it would get a qemu32 plus a bunch of
additional features instead.

This patch adds support for removing feature from the base model.
Selection algorithm remains the same: the best CPU model is the model
which requires lowest number of features to be added/removed from it.

When comparing a CPU to host CPU, the result would be
VIR_CPU_COMPARE_SUPERSET (or even VIR_CPU_COMPARE_INCOMPATIBLE if strict
match was required) even though the two CPUs were identical.

No change in semantics.

Useful mainly for migration. cpuUpdate changes guest CPU requirements in
the following way:

- match == "strict" || match == "exact"
    - optional features which are supported by host CPU are changed into
      required features
    - optional features which are not supported by host CPU are disabled
    - all other features remain untouched
- match == "minimum"
    - match is changed into "exact"
    - optional features and all features not mentioned in guest CPU
      specification which are supported by host CPU become required
      features
    - other optional features are disabled
    - all other features remain untouched

This ensures that no feature will suddenly disappear from the guest
after migration.

* global: patch created by running:
for f in $(git ls-files '*.[ch]') ; do
    cppi $f > $f.t && mv $f.t $f
done

* src/cpu/cpu_x86.c (x86Decode): Don't dereference NULL when passed
a NULL "models" pointer, or when passed a nonzero "nmodels" value
and a corresponding NULL models[i].

Baseline CPU is the best CPU which can be used for a guest on any of the
hosts.

All other libvirt functions use array first and then number of elements
in that array. Let's make cpuDecode follow this rule.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

The virConnectPtr is no longer required for error reporting since
that is recorded in a thread local. Remove use of virConnectPtr
from all APIs in cpu_conf.{h,c} and update all callers to
match

It was used for error reporting only.

Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

* src/cpu/cpu_x86.c (x86Decode): Do not dereference NULL
when "models" is NULL and nmodels is 1 or greater.

When comparing incompatible CPUs, the reason for this incompatibility is
logged as a debug message.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

When comparing x86 CPUs, features with 'disabled' policy were mistakenly
required to be supported by the host CPU.

Likewise, features with 'force' policy which were supported by host CPU
would make CPUs incompatible if 'strict' match was used by guest CPU.

This patch fixes both issues.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

Current implementation of x86Decode() used for CPUID -> model+features
translation does not always select the closest CPU model. When walking
through all models from cpu_map.xml the function considers a new
candidate as a better choice than a previously selected candidate only
if the new one is a superset of the old one. In case the new candidate
is closer to host CPU but lacks some feature comparing to the old
candidate, the function does not choose well.

This patch changes the algorithm so that the closest model is always
selected. That is, the model which requires the lowest number of
additional features to describe host CPU.
Signed-off-by: NJiri Denemark <jdenemar@redhat.com>

Also backup and restore the original ctxt->node value in x86FeatureLoad.

Each driver supporting CPU selection must fill in host CPU capabilities.
When filling them, drivers for hypervisors running on the same node as
libvirtd can use cpuNodeData() to obtain raw CPU data. Other drivers,
such as VMware, need to implement their own way of getting such data.
Raw data can be decoded into virCPUDefPtr using cpuDecode() function.

When implementing virConnectCompareCPU(), a hypervisor driver can just
call cpuCompareXML() function with host CPU capabilities.

For each guest for which a driver supports selecting CPU models, it must
set the appropriate feature in guest's capabilities:

    virCapabilitiesAddGuestFeature(guest, "cpuselection", 1, 0)

Actions needed when a domain is being created depend on whether the
hypervisor understands raw CPU data (currently CPUID for i686, x86_64
architectures) or symbolic names has to be used.

Typical use by hypervisors which prefer CPUID (such as VMware and Xen):

- convert guest CPU configuration from domain's XML into a set of raw
  data structures each representing one of the feature policies:

    cpuEncode(conn, architecture, guest_cpu_config,
              &forced_data, &required_data, &optional_data,
              &disabled_data, &forbidden_data)

- create a mask or whatever the hypervisor expects to see and pass it
  to the hypervisor

Typical use by hypervisors with symbolic model names (such as QEMU):

- get raw CPU data for a computed guest CPU:

    cpuGuestData(conn, host_cpu, guest_cpu_config, &data)

- decode raw data into virCPUDefPtr with a possible restriction on
  allowed model names:

    cpuDecode(conn, guest, data, n_allowed_models, allowed_models)

- pass guest->model and guest->features to the hypervisor

* src/cpu/cpu.c src/cpu/cpu.h src/cpu/cpu_generic.c
  src/cpu/cpu_generic.h src/cpu/cpu_map.c src/cpu/cpu_map.h
  src/cpu/cpu_x86.c src/cpu/cpu_x86.h src/cpu/cpu_x86_data.h
* configure.in: check for CPUID instruction
* src/Makefile.am: glue the new files in
* src/libvirt_private.syms: add new private symbols
* po/POTFILES.in: add new cpu files containing translatable strings