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Re: [PATCH v1 06/11] KVM: x86: use hardware-compatible format for APIC ID register

From Paolo Bonzini <pbonzini@redhat.com>
Newsgroups linux.kernel
Subject Re: [PATCH v1 06/11] KVM: x86: use hardware-compatible format for APIC ID register
Date 2016-07-01 16:20 +0200
Message-ID <rQ7st-7Fq-9@gated-at.bofh.it> (permalink)
References <rPRe1-5Ou-3@gated-at.bofh.it> <rPRe2-5Ou-19@gated-at.bofh.it> <rQ29s-4m1-27@gated-at.bofh.it> <rQ6wp-76i-17@gated-at.bofh.it>
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On 01/07/2016 15:11, Radim Krčmář wrote:
>>> >> +static void __kvm_apic_state_fixup(struct kvm_vcpu *vcpu,
>>> >> +		struct kvm_lapic_state *s, bool set)
>>> >> +{
>>> >> +	if (apic_x2apic_mode(vcpu->arch.apic)) {
>>> >> +		u32 *id = (u32 *)(s->regs + APIC_ID);
>>> >> +		if (set)
>>> >> +			*id >>= 24;
>>> >> +		else
>>> >> +			*id <<= 24;
>>> >> +	}
>> > 
>> > When setting, this should read from the apic_base being set.  So I think
>> > you cannot use apic_x2apic_mode.
> 
> apic_x2apic_mode uses apic_base MSR, so its value does not depend on
> LAPIC_SET/GET.  I don't like the dependency much, but all combinations
> of values/orders should work well.

You're right of course.  However it should be documented in the
KVM_GET_LAPIC/KVM_SET_LAPIC ioctl docs that KVM_SET_MSR for apic_base
should be performed first.

Should kvm_lapic_set_base change the value of the ID register when
x2apic mode is left just like we do for entering x2apic mode?  (Hint: we
want kvm-unit-tests for this).

Paolo

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Thread

[PATCH v1 00/11] KVM: x86: break the xAPIC barrier Radim Krčmář <rkrcmar@redhat.com> - 2016-06-30 23:00 +0200
  [PATCH v1 06/11] KVM: x86: use hardware-compatible format for APIC ID register Radim Krčmář <rkrcmar@redhat.com> - 2016-06-30 23:00 +0200
    Re: [PATCH v1 06/11] KVM: x86: use hardware-compatible format for  APIC ID register Paolo Bonzini <pbonzini@redhat.com> - 2016-07-01 10:40 +0200
      Re: [PATCH v1 06/11] KVM: x86: use hardware-compatible format for  APIC ID register Radim Krčmář <rkrcmar@redhat.com> - 2016-07-01 15:20 +0200
        Re: [PATCH v1 06/11] KVM: x86: use hardware-compatible format for  APIC ID register Paolo Bonzini <pbonzini@redhat.com> - 2016-07-01 16:20 +0200
          Re: [PATCH v1 06/11] KVM: x86: use hardware-compatible format for  APIC ID register Radim Krčmář <rkrcmar@redhat.com> - 2016-07-01 17:00 +0200
            Re: [PATCH v1 06/11] KVM: x86: use hardware-compatible format for  APIC ID register Paolo Bonzini <pbonzini@redhat.com> - 2016-07-01 17:10 +0200
              Re: [PATCH v1 06/11] KVM: x86: use hardware-compatible format for  APIC ID register Radim Krčmář <rkrcmar@redhat.com> - 2016-07-01 18:00 +0200
                Re: [PATCH v1 06/11] KVM: x86: use hardware-compatible format for  APIC ID register Paolo Bonzini <pbonzini@redhat.com> - 2016-07-01 18:40 +0200
  [PATCH v1 10/11] KVM: x86: add KVM_CAP_X2APIC_API Radim Krčmář <rkrcmar@redhat.com> - 2016-06-30 23:00 +0200
    Re: [PATCH v1 10/11] KVM: x86: add KVM_CAP_X2APIC_API Paolo Bonzini <pbonzini@redhat.com> - 2016-07-01 10:30 +0200
      Re: [PATCH v1 10/11] KVM: x86: add KVM_CAP_X2APIC_API Radim Krčmář <rkrcmar@redhat.com> - 2016-07-01 15:30 +0200
    Re: [PATCH v1 10/11] KVM: x86: add KVM_CAP_X2APIC_API David Matlack <dmatlack@google.com> - 2016-07-01 20:20 +0200
      Re: [PATCH v1 10/11] KVM: x86: add KVM_CAP_X2APIC_API Radim Krčmář <rkrcmar@redhat.com> - 2016-07-01 20:40 +0200
  [PATCH v1 04/11] KVM: x86: use u16 for logical VCPU mask in lapic Radim Krčmář <rkrcmar@redhat.com> - 2016-06-30 23:00 +0200
    Re: [PATCH v1 04/11] KVM: x86: use u16 for logical VCPU mask in lapic Paolo Bonzini <pbonzini@redhat.com> - 2016-07-01 10:20 +0200
      Re: [PATCH v1 04/11] KVM: x86: use u16 for logical VCPU mask in lapic Radim Krčmář <rkrcmar@redhat.com> - 2016-07-01 14:50 +0200
        Re: [PATCH v1 04/11] KVM: x86: use u16 for logical VCPU mask in lapic Paolo Bonzini <pbonzini@redhat.com> - 2016-07-01 16:20 +0200
  [PATCH v1 07/11] KVM: VMX: optimize APIC ID read with APICv Radim Krčmář <rkrcmar@redhat.com> - 2016-06-30 23:00 +0200
  [PATCH v1 03/11] KVM: x86: dynamic kvm_apic_map Radim Krčmář <rkrcmar@redhat.com> - 2016-06-30 23:00 +0200
    Re: [PATCH v1 03/11] KVM: x86: dynamic kvm_apic_map Andrew Honig <ahonig@google.com> - 2016-07-01 00:20 +0200
      Re: [PATCH v1 03/11] KVM: x86: dynamic kvm_apic_map Paolo Bonzini <pbonzini@redhat.com> - 2016-07-01 10:50 +0200
        Re: [PATCH v1 03/11] KVM: x86: dynamic kvm_apic_map Radim Krčmář <rkrcmar@redhat.com> - 2016-07-01 14:50 +0200
          Re: [PATCH v1 03/11] KVM: x86: dynamic kvm_apic_map Paolo Bonzini <pbonzini@redhat.com> - 2016-07-01 16:10 +0200
            Re: [PATCH v1 03/11] KVM: x86: dynamic kvm_apic_map Radim Krčmář <rkrcmar@redhat.com> - 2016-07-01 16:40 +0200
              Re: [PATCH v1 03/11] KVM: x86: dynamic kvm_apic_map Paolo Bonzini <pbonzini@redhat.com> - 2016-07-01 17:10 +0200
                Re: [PATCH v1 03/11] KVM: x86: dynamic kvm_apic_map Paolo Bonzini <pbonzini@redhat.com> - 2016-07-01 17:20 +0200
                Re: [PATCH v1 03/11] KVM: x86: dynamic kvm_apic_map Radim Krčmář <rkrcmar@redhat.com> - 2016-07-01 18:00 +0200
                Re: [PATCH v1 03/11] KVM: x86: dynamic kvm_apic_map Paolo Bonzini <pbonzini@redhat.com> - 2016-07-01 18:40 +0200
                Re: [PATCH v1 03/11] KVM: x86: dynamic kvm_apic_map Radim Krčmář <rkrcmar@redhat.com> - 2016-07-01 17:40 +0200
    Re: [PATCH v1 03/11] KVM: x86: dynamic kvm_apic_map Paolo Bonzini <pbonzini@redhat.com> - 2016-07-01 09:40 +0200
  [PATCH v1 01/11] KVM: x86: bump KVM_SOFT_MAX_VCPUS to 240 Radim Krčmář <rkrcmar@redhat.com> - 2016-06-30 23:00 +0200
    Re: [PATCH v1 01/11] KVM: x86: bump KVM_SOFT_MAX_VCPUS to 240 Paolo Bonzini <pbonzini@redhat.com> - 2016-07-01 10:50 +0200
  [PATCH v1 05/11] KVM: x86: use generic function for MSI parsing Radim Krčmář <rkrcmar@redhat.com> - 2016-06-30 23:00 +0200
  [PATCH v1 11/11] KVM: x86: bump MAX_VCPUS to 288 Radim Krčmář <rkrcmar@redhat.com> - 2016-06-30 23:00 +0200
    Re: [PATCH v1 11/11] KVM: x86: bump MAX_VCPUS to 288 Paolo Bonzini <pbonzini@redhat.com> - 2016-07-01 10:50 +0200
  [PATCH v1 09/11] KVM: x86: reset lapic base in kvm_lapic_reset Radim Krčmář <rkrcmar@redhat.com> - 2016-06-30 23:00 +0200
    Re: [PATCH v1 09/11] KVM: x86: reset lapic base in kvm_lapic_reset Paolo Bonzini <pbonzini@redhat.com> - 2016-07-01 10:50 +0200
  [PATCH v1 02/11] KVM: x86: add kvm_apic_map_get_dest_lapic Radim Krčmář <rkrcmar@redhat.com> - 2016-06-30 23:00 +0200
    Re: [PATCH v1 02/11] KVM: x86: add kvm_apic_map_get_dest_lapic Paolo Bonzini <pbonzini@redhat.com> - 2016-07-01 10:00 +0200
      Re: [PATCH v1 02/11] KVM: x86: add kvm_apic_map_get_dest_lapic Radim Krčmář <rkrcmar@redhat.com> - 2016-07-01 14:50 +0200
  [PATCH v1 08/11] KVM: x86: directly call recalculate_apic_map on lapic restore Radim Krčmář <rkrcmar@redhat.com> - 2016-06-30 23:00 +0200

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