CMGS ba11523760 arch: x86_64: advertise additional Hyper-V CPUID enlightenments ...

Extends the Hyper-V partition feature CPUID leaf 0x40000003 with bits
that KVM emulates unconditionally and that Windows / Hyper-V-aware
guests consult to skip slow fallback paths. No KVM capability
negotiation is required for any of these -- they are hints to the
guest about what is already legal to use.

Leaf 0x40000003.EAX (HV_CPUID_FEATURES):
  bit 0  AccessVpRuntimeReg     -- HV_X64_MSR_VP_RUNTIME (0x40000010)
  bit 4  AccessIntrCtrlRegs     -- HV_X64_MSR_{EOI,ICR,TPR,APIC_ASSIST}
  bit 11 AccessFrequencyMsrs    -- HV_X64_MSR_{TSC,APIC}_FREQUENCY (skips
                                   guest TSC/APIC calibration loops)

Leaf 0x40000003.EDX (HV_CPUID_FEATURES, TLFS rev 6.0c):
  bit 4  FastHypercall          -- HV_HYPERCALL_PARAMS_XMM_AVAILABLE
  bit 8  ExtendedGvaRangesForFlushVirtualAddressList -- pairs with the
                                   tlbflush-ext recommendation bit

AccessHypercallMsrs (bit 5) and AccessVpIndex (bit 6) are already
advertised by the partition-privileges change.

Sources:
  Microsoft Hypervisor Top-Level Functional Specification 7.4.{2,5}
  qemu/qemu docs/system/i386/hyperv.rst (hv-vapic, hv-frequencies,
                                          hv-vpruntime)

Signed-off-by: CMGS <ilskdw@gmail.com>

2026-06-29 18:03:44 +00:00

..

src

arch: x86_64: advertise additional Hyper-V CPUID enlightenments

2026-06-29 18:03:44 +00:00

Cargo.toml

arch: Helper functions for u32 hex (de-) serialization

2026-05-28 15:19:15 +00:00