* [PATCH] KVM: x86: preserve x2APIC LDR on INIT
@ 2015-05-22 17:22 Radim Krčmář
2015-05-26 10:38 ` Paolo Bonzini
0 siblings, 1 reply; 2+ messages in thread
From: Radim Krčmář @ 2015-05-22 17:22 UTC (permalink / raw)
To: linux-kernel; +Cc: kvm, Paolo Bonzini
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 Krčmář <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);
--
2.4.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] KVM: x86: preserve x2APIC LDR on INIT
2015-05-22 17:22 [PATCH] KVM: x86: preserve x2APIC LDR on INIT Radim Krčmář
@ 2015-05-26 10:38 ` Paolo Bonzini
0 siblings, 0 replies; 2+ messages in thread
From: Paolo Bonzini @ 2015-05-26 10:38 UTC (permalink / raw)
To: Radim Krčmář, linux-kernel; +Cc: kvm
On 22/05/2015 19:22, Radim Krčmář 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 Krčmář <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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