diff mbox

KVM: x86: preserve x2APIC LDR on INIT

Message ID 1432315330-20872-1-git-send-email-rkrcmar@redhat.com (mailing list archive)
State New, archived
Headers show

Commit Message

Radim Krčmář May 22, 2015, 5:22 p.m. UTC
Logical x2APIC stops working if we rewrite it with zeros.
The best references are SDM April 2015: 10.12.10.1 Logical Destination
Mode in x2APIC Mode

  [...], the LDR are initialized by hardware based on the value of
  x2APIC ID upon x2APIC state transitions.

and SDM April 2015: 10.12.10.2 Deriving Logical x2APIC ID from the Local
x2APIC ID

  The LDR initialization occurs whenever the x2APIC mode is enabled

Signed-off-by: Radim Kr?má? <rkrcmar@redhat.com>
---
 arch/x86/kvm/lapic.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Comments

Paolo Bonzini May 26, 2015, 10:38 a.m. UTC | #1
On 22/05/2015 19:22, Radim Kr?má? wrote:
> Logical x2APIC stops working if we rewrite it with zeros.
> The best references are SDM April 2015: 10.12.10.1 Logical Destination
> Mode in x2APIC Mode
> 
>   [...], the LDR are initialized by hardware based on the value of
>   x2APIC ID upon x2APIC state transitions.
> 
> and SDM April 2015: 10.12.10.2 Deriving Logical x2APIC ID from the Local
> x2APIC ID
> 
>   The LDR initialization occurs whenever the x2APIC mode is enabled
> 
> Signed-off-by: Radim Kr?má? <rkrcmar@redhat.com>
> ---
>  arch/x86/kvm/lapic.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index c2a7d8a7a414..c789e00dfa8b 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -1594,7 +1594,8 @@ void kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event)
>  	apic_set_reg(apic, APIC_DFR, 0xffffffffU);
>  	apic_set_spiv(apic, 0xff);
>  	apic_set_reg(apic, APIC_TASKPRI, 0);
> -	kvm_apic_set_ldr(apic, 0);
> +	if (!apic_x2apic_mode(apic))
> +		kvm_apic_set_ldr(apic, 0);
>  	apic_set_reg(apic, APIC_ESR, 0);
>  	apic_set_reg(apic, APIC_ICR, 0);
>  	apic_set_reg(apic, APIC_ICR2, 0);
> 

Applied, thanks.

Paolo
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diff mbox

Patch

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index c2a7d8a7a414..c789e00dfa8b 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1594,7 +1594,8 @@  void kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event)
 	apic_set_reg(apic, APIC_DFR, 0xffffffffU);
 	apic_set_spiv(apic, 0xff);
 	apic_set_reg(apic, APIC_TASKPRI, 0);
-	kvm_apic_set_ldr(apic, 0);
+	if (!apic_x2apic_mode(apic))
+		kvm_apic_set_ldr(apic, 0);
 	apic_set_reg(apic, APIC_ESR, 0);
 	apic_set_reg(apic, APIC_ICR, 0);
 	apic_set_reg(apic, APIC_ICR2, 0);