[PATCH 00/12] Introducing AMD x2APIC Virtualization (x2AVIC) support.

From: Suravee Suthikulpanit
Date: Tue Apr 05 2022 - 23:01:47 EST

Previously, with AVIC, guest needs to disable x2APIC capability and
can only run in APIC mode to activate hardware-accelerated interrupt
virtualization. With x2AVIC, guest can run in x2APIC mode.
This feature is indicated by the CPUID Fn8000_000A EDX[14],
and it can be activated by setting bit 31 (enable AVIC) and
bit 30 (x2APIC mode) of VMCB offset 60h.

The mode of interrupt virtualization can dynamically change during runtime.
For example, when AVIC is enabled, the hypervisor currently keeps track of
the AVIC activation and set the VMCB bit 31 accordingly. With x2AVIC,
the guest OS can also switch between APIC and x2APIC modes during runtime.
The kvm_amd driver needs to also keep track and set the VMCB
bit 30 accordingly.

Besides, for x2AVIC, kvm_amd driver needs to disable interception for the
x2APIC MSR range to allow AVIC hardware to virtualize register accesses.

* This series has been tested booting a Linux VM with x2APIC physical
and logical modes upto 512 vCPUs.


Change from RFCv2 (https://lore.kernel.org/all/5876774a-c188-2026-1328-a4292022832b@xxxxxxx/t/)
* Rebase to v5.17
* Clean up based on review comments from Maxim (Thank!!)
* Patch 6/12: Remove the kvm_get_apic_id() introduced in RFCv2, and
simply do not support updating physical and logical ID when in x2APIC mode.
* Patch 7/12: Extend the svm_direct_access_msrs to include x2APIC MSR range
instead of declaring a new data structure.
* Patch 8/12: Remove force svm_refresh_apicv_exec_ctrl(), and do not
update avic_vapic_bar.
* Patch 12/12: New to this series.

Suravee Suthikulpanit (12):
x86/cpufeatures: Introduce x2AVIC CPUID bit
KVM: x86: lapic: Rename [GET/SET]_APIC_DEST_FIELD to
KVM: SVM: Detect X2APIC virtualization (x2AVIC) support
KVM: SVM: Update max number of vCPUs supported for x2AVIC mode
KVM: SVM: Update avic_kick_target_vcpus to support 32-bit APIC ID
KVM: SVM: Do not support updating APIC ID when in x2APIC mode
KVM: SVM: Adding support for configuring x2APIC MSRs interception
KVM: SVM: Update AVIC settings when changing APIC mode
KVM: SVM: Introduce helper functions to (de)activate AVIC and x2AVIC
KVM: SVM: Do not throw warning when calling avic_vcpu_load on a
running vcpu
KVM: SVM: Do not inhibit APICv when x2APIC is present
kvm/x86: Remove APICV activate mode inconsistency check

arch/x86/hyperv/hv_apic.c | 2 +-
arch/x86/include/asm/apicdef.h | 4 +-
arch/x86/include/asm/cpufeatures.h | 1 +
arch/x86/include/asm/svm.h | 16 ++-
arch/x86/kernel/apic/apic.c | 2 +-
arch/x86/kernel/apic/ipi.c | 2 +-
arch/x86/kvm/lapic.c | 2 +-
arch/x86/kvm/svm/avic.c | 151 ++++++++++++++++++++++++++---
arch/x86/kvm/svm/svm.c | 56 ++++++-----
arch/x86/kvm/svm/svm.h | 7 +-
arch/x86/kvm/x86.c | 13 +--
11 files changed, 202 insertions(+), 54 deletions(-)