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. Testing: * This series has been tested booting a Linux VM with x2APIC physical and logical modes upto 512 vCPUs. Regards, Suravee 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 [GET/SET]_XAPIC_DEST_FIELD 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(-) -- 2.25.1