[PATCH 0/4] Export APICv-related state via binary stats interface

[Alejandro Jimenez]

After discussion in the RFC thread[0], the following items were identified as
desirable to expose via the stats interface:

- APICv status: (apicv_enabled, boolean, per-vCPU)

- Guest using SynIC's AutoEOI: (synic_auto_eoi_used, boolean, per-VM)

- KVM PIT in reinject mode inhibits AVIC: (pit_reinject_mode, boolean, per-VM)

- APICv unaccelerated injections causing a vmexit (i.e. AVIC_INCOMPLETE_IPI,
  AVIC_UNACCELERATED_ACCESS, APIC_WRITE): (apicv_unaccelerated_inj, counter,
  per-vCPU)

Example retrieving the newly introduced stats for guest running on AMD Genoa
host, with AVIC enabled:

(QEMU) query-stats target=vcpu vcpus=['/machine/unattached/device[0]'] providers=[{'provider':'kvm','names':['apicv_unaccelerated_inj','apicv_active']}]
{
    "return": [
        {
            "provider": "kvm",
            "qom-path": "/machine/unattached/device[0]",
            "stats": [
                {
                    "name": "apicv_unaccelerated_inj",
                    "value": 2561
                },
                {
                    "name": "apicv_active",
                    "value": true
                }
            ]
        }
    ]
}
(QEMU) query-stats target=vm providers=[{'provider':'kvm','names':['pit_reinject_mode','synic_auto_eoi_used']}]
{
    "return": [
        {
            "provider": "kvm",
            "stats": [
                {
                    "name": "pit_reinject_mode",
                    "value": false
                },
                {
                    "name": "synic_auto_eoi_used",
                    "value": false
                }
            ]
        }
    ]
}

Changes were also sanity tested on Intel Sapphire Rapids platform, with/without
IPI virtualization.

Regards,
Alejandro

[0] https://lore.kernel.org/all/20240215160136.1256084-1-alejandro.j.jimenez@xxxxxxxxxx/

Alejandro Jimenez (4):
  KVM: x86: Expose per-vCPU APICv status
  KVM: x86: Add a VM stat exposing when SynIC AutoEOI is in use
  KVM: x86: Add a VM stat exposing when KVM PIT is set to reinject mode
  KVM: x86: Add vCPU stat for APICv interrupt injections causing #VMEXIT

 arch/x86/include/asm/kvm_host.h | 4 ++++
 arch/x86/kvm/hyperv.c           | 2 ++
 arch/x86/kvm/i8254.c            | 2 ++
 arch/x86/kvm/lapic.c            | 1 +
 arch/x86/kvm/svm/avic.c         | 7 +++++++
 arch/x86/kvm/vmx/vmx.c          | 2 ++
 arch/x86/kvm/x86.c              | 7 ++++++-
 7 files changed, 24 insertions(+), 1 deletion(-)


base-commit: 7b076c6a308ec5bce9fc96e2935443ed228b9148
-- 
2.39.3