From 35754c987f252e859bfa390a6816e85563afe79d Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Wed, 29 Jul 2015 12:05:37 +0200 Subject: KVM: x86: introduce lapic_in_kernel Avoid pointer chasing and memory barriers, and simplify the code when split irqchip (LAPIC in kernel, IOAPIC/PIC in userspace) is introduced. Signed-off-by: Paolo Bonzini --- arch/x86/kvm/irq.h | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'arch/x86/kvm/irq.h') diff --git a/arch/x86/kvm/irq.h b/arch/x86/kvm/irq.h index 3d782a2c336a..9e6e7e04de98 100644 --- a/arch/x86/kvm/irq.h +++ b/arch/x86/kvm/irq.h @@ -92,6 +92,14 @@ static inline int irqchip_in_kernel(struct kvm *kvm) return vpic != NULL; } +static inline int lapic_in_kernel(struct kvm_vcpu *vcpu) +{ + /* Same as irqchip_in_kernel(vcpu->kvm), but with less + * pointer chasing and no unnecessary memory barriers. + */ + return vcpu->arch.apic != NULL; +} + void kvm_pic_reset(struct kvm_kpic_state *s); void kvm_inject_pending_timer_irqs(struct kvm_vcpu *vcpu); -- cgit From 49df6397edfc5a8ba8ca813b51fb9729d8e94b40 Mon Sep 17 00:00:00 2001 From: Steve Rutherford Date: Wed, 29 Jul 2015 23:21:40 -0700 Subject: KVM: x86: Split the APIC from the rest of IRQCHIP. First patch in a series which enables the relocation of the PIC/IOAPIC to userspace. Adds capability KVM_CAP_SPLIT_IRQCHIP; KVM_CAP_SPLIT_IRQCHIP enables the construction of LAPICs without the rest of the irqchip. Compile tested for x86. Signed-off-by: Steve Rutherford Suggested-by: Andrew Honig Signed-off-by: Paolo Bonzini --- arch/x86/kvm/irq.h | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) (limited to 'arch/x86/kvm/irq.h') diff --git a/arch/x86/kvm/irq.h b/arch/x86/kvm/irq.h index 9e6e7e04de98..2f9703dcd913 100644 --- a/arch/x86/kvm/irq.h +++ b/arch/x86/kvm/irq.h @@ -83,13 +83,22 @@ static inline struct kvm_pic *pic_irqchip(struct kvm *kvm) return kvm->arch.vpic; } +static inline int irqchip_split(struct kvm *kvm) +{ + return kvm->arch.irqchip_split; +} + static inline int irqchip_in_kernel(struct kvm *kvm) { struct kvm_pic *vpic = pic_irqchip(kvm); + bool ret; + + ret = (vpic != NULL); + ret |= irqchip_split(kvm); /* Read vpic before kvm->irq_routing. */ smp_rmb(); - return vpic != NULL; + return ret; } static inline int lapic_in_kernel(struct kvm_vcpu *vcpu) -- cgit From 1c1a9ce973a7863dd46767226bce2a5f12d48bc6 Mon Sep 17 00:00:00 2001 From: Steve Rutherford Date: Thu, 30 Jul 2015 11:27:16 +0200 Subject: KVM: x86: Add support for local interrupt requests from userspace In order to enable userspace PIC support, the userspace PIC needs to be able to inject local interrupts even when the APICs are in the kernel. KVM_INTERRUPT now supports sending local interrupts to an APIC when APICs are in the kernel. The ready_for_interrupt_request flag is now only set when the CPU/APIC will immediately accept and inject an interrupt (i.e. APIC has not masked the PIC). When the PIC wishes to initiate an INTA cycle with, say, CPU0, it kicks CPU0 out of the guest, and renedezvous with CPU0 once it arrives in userspace. When the CPU/APIC unmasks the PIC, a KVM_EXIT_IRQ_WINDOW_OPEN is triggered, so that userspace has a chance to inject a PIC interrupt if it had been pending. Overall, this design can lead to a small number of spurious userspace renedezvous. In particular, whenever the PIC transistions from low to high while it is masked and whenever the PIC becomes unmasked while it is low. Note: this does not buffer more than one local interrupt in the kernel, so the VMM needs to enter the guest in order to complete interrupt injection before injecting an additional interrupt. Compiles for x86. Can pass the KVM Unit Tests. Signed-off-by: Steve Rutherford Signed-off-by: Paolo Bonzini --- arch/x86/kvm/irq.h | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'arch/x86/kvm/irq.h') diff --git a/arch/x86/kvm/irq.h b/arch/x86/kvm/irq.h index 2f9703dcd913..ae5c78f2337d 100644 --- a/arch/x86/kvm/irq.h +++ b/arch/x86/kvm/irq.h @@ -83,6 +83,14 @@ static inline struct kvm_pic *pic_irqchip(struct kvm *kvm) return kvm->arch.vpic; } +static inline int pic_in_kernel(struct kvm *kvm) +{ + int ret; + + ret = (pic_irqchip(kvm) != NULL); + return ret; +} + static inline int irqchip_split(struct kvm *kvm) { return kvm->arch.irqchip_split; -- cgit