[PATCH] KVM: x86: recalculate_apic_map after enabling apic

[PATCH] KVM: x86: recalculate_apic_map after enabling apic

[Nadav Amit]

Currently, recalculate_apic_map ignores vcpus whose lapic is software disabled
through the spurious interrupt vector. However, once it is re-enabled, the map
is not recalculated. Therefore, if the guest OS configured DFR while lapic is
software-disabled, the map may be incorrect. This patch recalculates apic map
after software enabling the lapic.

Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
---
 arch/x86/kvm/lapic.c | 25 ++++++++++++++-----------
 1 file changed, 14 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 08e8a89..4a736199 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -112,17 +112,6 @@ static inline int __apic_test_and_clear_vector(int vec, void *bitmap)
 struct static_key_deferred apic_hw_disabled __read_mostly;
 struct static_key_deferred apic_sw_disabled __read_mostly;
 
-static inline void apic_set_spiv(struct kvm_lapic *apic, u32 val)
-{
-	if ((kvm_apic_get_reg(apic, APIC_SPIV) ^ val) & APIC_SPIV_APIC_ENABLED) {
-		if (val & APIC_SPIV_APIC_ENABLED)
-			static_key_slow_dec_deferred(&apic_sw_disabled);
-		else
-			static_key_slow_inc(&apic_sw_disabled.key);
-	}
-	apic_set_reg(apic, APIC_SPIV, val);
-}
-
 static inline int apic_enabled(struct kvm_lapic *apic)
 {
 	return kvm_apic_sw_enabled(apic) &&	kvm_apic_hw_enabled(apic);
@@ -210,6 +199,20 @@ out:
 	kvm_vcpu_request_scan_ioapic(kvm);
 }
 
+static inline void apic_set_spiv(struct kvm_lapic *apic, u32 val)
+{
+	u32 prev = kvm_apic_get_reg(apic, APIC_SPIV);
+
+	apic_set_reg(apic, APIC_SPIV, val);
+	if ((prev ^ val) & APIC_SPIV_APIC_ENABLED) {
+		if (val & APIC_SPIV_APIC_ENABLED) {
+			static_key_slow_dec_deferred(&apic_sw_disabled);
+			recalculate_apic_map(apic->vcpu->kvm);
+		} else
+			static_key_slow_inc(&apic_sw_disabled.key);
+	}
+}
+
 static inline void kvm_apic_set_id(struct kvm_lapic *apic, u8 id)
 {
 	apic_set_reg(apic, APIC_ID, id << 24);
-- 
1.9.1

Re: [PATCH] KVM: x86: recalculate_apic_map after enabling apic

[Paolo Bonzini]

Il 18/08/2014 23:03, Nadav Amit ha scritto:
> Currently, recalculate_apic_map ignores vcpus whose lapic is software disabled
> through the spurious interrupt vector. However, once it is re-enabled, the map
> is not recalculated. Therefore, if the guest OS configured DFR while lapic is
> software-disabled, the map may be incorrect. This patch recalculates apic map
> after software enabling the lapic.
> 
> Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
> ---
>  arch/x86/kvm/lapic.c | 25 ++++++++++++++-----------
>  1 file changed, 14 insertions(+), 11 deletions(-)
> 
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index 08e8a89..4a736199 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -112,17 +112,6 @@ static inline int __apic_test_and_clear_vector(int vec, void *bitmap)
>  struct static_key_deferred apic_hw_disabled __read_mostly;
>  struct static_key_deferred apic_sw_disabled __read_mostly;
>  
> -static inline void apic_set_spiv(struct kvm_lapic *apic, u32 val)
> -{
> -	if ((kvm_apic_get_reg(apic, APIC_SPIV) ^ val) & APIC_SPIV_APIC_ENABLED) {
> -		if (val & APIC_SPIV_APIC_ENABLED)
> -			static_key_slow_dec_deferred(&apic_sw_disabled);
> -		else
> -			static_key_slow_inc(&apic_sw_disabled.key);
> -	}
> -	apic_set_reg(apic, APIC_SPIV, val);
> -}
> -
>  static inline int apic_enabled(struct kvm_lapic *apic)
>  {
>  	return kvm_apic_sw_enabled(apic) &&	kvm_apic_hw_enabled(apic);
> @@ -210,6 +199,20 @@ out:
>  	kvm_vcpu_request_scan_ioapic(kvm);
>  }
>  
> +static inline void apic_set_spiv(struct kvm_lapic *apic, u32 val)
> +{
> +	u32 prev = kvm_apic_get_reg(apic, APIC_SPIV);
> +
> +	apic_set_reg(apic, APIC_SPIV, val);
> +	if ((prev ^ val) & APIC_SPIV_APIC_ENABLED) {
> +		if (val & APIC_SPIV_APIC_ENABLED) {
> +			static_key_slow_dec_deferred(&apic_sw_disabled);
> +			recalculate_apic_map(apic->vcpu->kvm);
> +		} else
> +			static_key_slow_inc(&apic_sw_disabled.key);
> +	}
> +}
> +
>  static inline void kvm_apic_set_id(struct kvm_lapic *apic, u8 id)
>  {
>  	apic_set_reg(apic, APIC_ID, id << 24);
> 

Applied to kvm/queue, thanks.

Paolo