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

From Radim Krčmář <rkrcmar@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 15:20 +0200
Message-ID <rQ6wp-76i-17@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>
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2016-07-01 10:33+0200, Paolo Bonzini:
> On 30/06/2016 22:54, 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.

> With this change, you don't need the struct kvm_vcpu argument now; add a
> struct kvm argument instead in patch 10.

I don't think we can use hardware-compatible format in API without
knowing the x2apic mode through vcpu.
(The big endian format could do without knowing apic mode.)

>> @@ -2780,6 +2780,7 @@ static int kvm_vcpu_ioctl_get_lapic(struct kvm_vcpu *vcpu,
>>  		kvm_x86_ops->sync_pir_to_irr(vcpu);
>>  
>>  	memcpy(s->regs, vcpu->arch.apic->regs, sizeof *s);
>> +	kvm_apic_state_get_fixup(vcpu, s);
> 
> Instead of kvm_apic_state_get/set_fixup, group the memcpy and
> __kvm_apic_state_fixup in a new function kvm_apic_get_state(struct
> kvm_lapic *apic, char *regs).

Ok.

>>  	return 0;
>>  }
>> @@ -2787,6 +2788,7 @@ static int kvm_vcpu_ioctl_get_lapic(struct kvm_vcpu *vcpu,
>>  static int kvm_vcpu_ioctl_set_lapic(struct kvm_vcpu *vcpu,
>>  				    struct kvm_lapic_state *s)
>>  {
>> +	kvm_apic_state_set_fixup(vcpu, s);
>>  	kvm_apic_post_state_restore(vcpu, s);
> 
> ... and likewise merge these two in a refactored
> kvm_apic_post_state_restore called kvm_apic_set_state(struct kvm_lapic
> *apic, char *regs), by calling __kvm_apic_state_fixup before
> kvm_apic_post_state_restore's memcpy.
> 
> With these changes I guess there's no need for the underscores in
> __kvm_apic_state_fixup.

Yes, good idea.

>                          And you can also change the struct
> kvm_lapic_state pointer in the function to a char *.

Ok, I'll pass just s->regs.

Thanks.

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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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