add Opteron_G4 CPU model (v2)

add Opteron_G4 CPU model (v2)

This patch addes a Bulldozer-based Opteron_G4 CPU model.

This version has the ffxsr bit actually disabled, to match what was
documented below. Thanks to Andre Przywara for spotting the bug.

I am trying to be conservative with the new model, so I am enabling only
features known to be useful to guests, and not enabling anything that
was not tested or found to be useful to a guest.

List of missing flags in comparison to real hardware:

- vme: host-specific feature.
- osxsave: it is not set here because it is set by the guest OS, not by KVM
- monitor: this is filtered out by the KVM module, so no point in
  enabling it.
- mmxext: untested, so not enabled.
- Perf*, Topology*, lwp, ibs: not emulated by KVM.
- wdt, skinit, osvw, altmovcr8, extapicspace, cmplegacy: untested,
  so not enabled.

List of new flags, in comparison to the Opteron_G3 model:

- xsave: xsave feature, already implemented by Qemu
- avx, aes, sse4.x, ssse3, pclmulqdq: all new state the new instructions
  could use is handled by the xsave state loading/saving code on Qemu.
- pdpe1gb: 1GB pages, supported by the KVM kernel module.
- ffxsr: untested, so not enabled
- fma4, xop: all new state the new instructions could use is handled by
  the xsave loading/saving code on Qemu.
- 3dnowprefetch: safe to pass through, though the flag is not used by
  Linux guests, at least.

Below is the comparison between the current Opteron_G3 model
and the new model being added.

- The "full" line contains the flags found on actual hardware.
- The "missing" line shows the flags that are present on actual
  hardware, but not on the added Opteron_G4 model.
- The "new" line shows the flags that were not on the Opteron_G3 model
  but are on Opteron_G4.

feature_edx:
  Opteron_G3: sse2 sse fxsr mmx clflush pse36 pat cmov mca pge mtrr sep apic cx8 mce pae msr tsc pse de     fpu
  full:       sse2 sse fxsr mmx clflush pse36 pat cmov mca pge mtrr sep apic cx8 mce pae msr tsc pse de vme fpu
  Opteron_G4: sse2 sse fxsr mmx clflush pse36 pat cmov mca pge mtrr sep apic cx8 mce pae msr tsc pse de     fpu
  missing:                                                                                              vme

feature_ecx:
  Opteron_G3:                       popcnt               cx16       monitor           sse3
  full:       avx osxsave xsave aes popcnt sse4.2 sse4.1 cx16 ssse3 monitor pclmulqdq sse3
  Opteron_G4: avx         xsave aes popcnt sse4.2 sse4.1 cx16 ssse3         pclmulqdq sse3
  missing:        osxsave                                           monitor
  new:        avx         xsave aes        sse4.2 sse4.1      ssse3         pclmulqdq

extfeature_edx:
  Opteron_G3: lm rdtscp               fxsr mmx        nx pse36 pat cmov mca pge mtrr syscall apic cx8 mce pae msr tsc pse de     fpu
  full:       lm rdtscp pdpe1gb ffxsr fxsr mmx mmxext nx pse36 pat cmov mca pge mtrr syscall apic cx8 mce pae msr tsc pse de vme fpu
  Opteron_G4: lm rdtscp pdpe1gb       fxsr mmx        nx pse36 pat cmov mca pge mtrr syscall apic cx8 mce pae msr tsc pse de     fpu
  missing:                                     mmxext                                                                        vme
  new:                  pdpe1gb

extfeature_ecx:
  Opteron_G3:                                                                misalignsse sse4a abm                        svm           lahf_lm
  full:       Perf* Topology* fma4 lwp wdt skinit xop ibs osvw 3dnowprefetch misalignsse sse4a abm altmovcr8 extapicspace svm cmplegacy lahf_lm
  Opteron_G4:                 fma4                xop          3dnowprefetch misalignsse sse4a abm                        svm           lahf_lm
  new:                        fma4                xop          3dnowprefetch
  missing:    Perf* Topology*      lwp wdt skinit     ibs osvw                                     altmovcr8 extapicspace     cmplegacy

Changes v1 -> v2:
 - Actually disable ffxsr bit

Cc: Andre Przywara <andre.przywara@amd.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>