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    Subject[PATCH v3 0/4] KVM: x86: hyper-v: Conditionally allow SynIC with APICv/AVIC
    Date
    Changes since v2:
    - First two patches got merged, rebase.
    - Use 'enable_apicv = avic = ...' in PATCH1 [Paolo]
    - Collect R-b tags for PATCH2 [Sean, Max]
    - Use hv_apicv_update_work() to get out of SRCU lock [Max]
    - "KVM: x86: Check for pending interrupts when APICv is getting disabled"
    added.

    Original description:

    APICV_INHIBIT_REASON_HYPERV is currently unconditionally forced upon
    SynIC activation as SynIC's AutoEOI is incompatible with APICv/AVIC. It is,
    however, possible to track whether the feature was actually used by the
    guest and only inhibit APICv/AVIC when needed.

    The series can be tested with the followin hack:

    diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
    index 9a48f138832d..65a9974f80d9 100644
    --- a/arch/x86/kvm/cpuid.c
    +++ b/arch/x86/kvm/cpuid.c
    @@ -147,6 +147,13 @@ void kvm_update_cpuid_runtime(struct kvm_vcpu *vcpu)
    vcpu->arch.ia32_misc_enable_msr &
    MSR_IA32_MISC_ENABLE_MWAIT);
    }
    +
    + /* Dirty hack: force HV_DEPRECATING_AEOI_RECOMMENDED. Not to be merged! */
    + best = kvm_find_cpuid_entry(vcpu, HYPERV_CPUID_ENLIGHTMENT_INFO, 0);
    + if (best) {
    + best->eax &= ~HV_X64_APIC_ACCESS_RECOMMENDED;
    + best->eax |= HV_DEPRECATING_AEOI_RECOMMENDED;
    + }
    }
    EXPORT_SYMBOL_GPL(kvm_update_cpuid_runtime);

    Vitaly Kuznetsov (4):
    KVM: x86: Use common 'enable_apicv' variable for both APICv and AVIC
    KVM: x86: Drop vendor specific functions for APICv/AVIC enablement
    KVM: x86: Check for pending interrupts when APICv is getting disabled
    KVM: x86: hyper-v: Deactivate APICv only when AutoEOI feature is in
    use
    arch/x86/include/asm/kvm_host.h | 9 +++++-
    arch/x86/kvm/hyperv.c | 51 +++++++++++++++++++++++++++++----
    arch/x86/kvm/svm/avic.c | 14 ++++-----
    arch/x86/kvm/svm/svm.c | 22 ++++++++------
    arch/x86/kvm/svm/svm.h | 2 --
    arch/x86/kvm/vmx/capabilities.h | 1 -
    arch/x86/kvm/vmx/vmx.c | 2 --
    arch/x86/kvm/x86.c | 18 ++++++++++--
    8 files changed, 86 insertions(+), 33 deletions(-)
    --
    2.31.1

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