| Message ID | 20120915153605.21241.75455.stgit@ubuntu (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Sat, Sep 15, 2012 at 04:36:05PM +0100, Christoffer Dall wrote: > From: Christoffer Dall <cdall@cs.columbia.edu> > > When the guest executes a WFI instruction the operation is trapped to > KVM, which emulates the instruction in software. There is no correlation > between a guest executing a WFI instruction and actually putting the > hardware into a low-power mode, since a KVM guest is essentially a > process and the WFI instruction can be seen as 'sleep' call from this > process. Therefore, we block the vcpu when the guest excecutes a wfi > instruction and the IRQ or FIQ lines are not raised. > > When an interrupt comes in through KVM_IRQ_LINE (see previous patch) we > signal the VCPU thread and unflag the VCPU to no longer wait for > interrupts. Seems a bit strange tagging this small addition on the end of this series. Can you merge it in with the rest? Will -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Sep 25, 2012 at 1:04 PM, Will Deacon <will.deacon@arm.com> wrote: > On Sat, Sep 15, 2012 at 04:36:05PM +0100, Christoffer Dall wrote: >> From: Christoffer Dall <cdall@cs.columbia.edu> >> >> When the guest executes a WFI instruction the operation is trapped to >> KVM, which emulates the instruction in software. There is no correlation >> between a guest executing a WFI instruction and actually putting the >> hardware into a low-power mode, since a KVM guest is essentially a >> process and the WFI instruction can be seen as 'sleep' call from this >> process. Therefore, we block the vcpu when the guest excecutes a wfi >> instruction and the IRQ or FIQ lines are not raised. >> >> When an interrupt comes in through KVM_IRQ_LINE (see previous patch) we >> signal the VCPU thread and unflag the VCPU to no longer wait for >> interrupts. > > Seems a bit strange tagging this small addition on the end of this series. > Can you merge it in with the rest? > sure, I'll tag it in with the world-switch or emulation. -Christoffer -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c index 06a3368..64fbec7 100644 --- a/arch/arm/kvm/arm.c +++ b/arch/arm/kvm/arm.c @@ -318,9 +318,16 @@ int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu, return -EINVAL; } +/** + * kvm_arch_vcpu_runnable - determine if the vcpu can be scheduled + * @v: The VCPU pointer + * + * If the guest CPU is not waiting for interrupts or an interrupt line is + * asserted, the CPU is by definition runnable. + */ int kvm_arch_vcpu_runnable(struct kvm_vcpu *v) { - return 0; + return !!v->arch.irq_lines; } int kvm_arch_vcpu_in_guest_mode(struct kvm_vcpu *v) @@ -586,7 +593,6 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run) * Check conditions before entering the guest */ cond_resched(); - update_vttbr(vcpu->kvm); local_irq_disable(); diff --git a/arch/arm/kvm/emulate.c b/arch/arm/kvm/emulate.c index 2670679..fc0fcd3 100644 --- a/arch/arm/kvm/emulate.c +++ b/arch/arm/kvm/emulate.c @@ -154,9 +154,20 @@ static int kvm_instr_index(u32 instr, u32 table[][2], int table_entries) return INSTR_NONE; } +/** + * kvm_handle_wfi - handle a wait-for-interrupts instruction executed by a guest + * @vcpu: the vcpu pointer + * @run: the kvm_run structure pointer + * + * Simply sets the wait_for_interrupts flag on the vcpu structure, which will + * halt execution of world-switches and schedule other host processes until + * there is an incoming IRQ or FIQ to the VM. + */ int kvm_handle_wfi(struct kvm_vcpu *vcpu, struct kvm_run *run) { - return 0; + trace_kvm_wfi(vcpu->arch.regs.pc); + kvm_vcpu_block(vcpu); + return 1; } diff --git a/arch/arm/kvm/trace.h b/arch/arm/kvm/trace.h index 7199b58..b371138 100644 --- a/arch/arm/kvm/trace.h +++ b/arch/arm/kvm/trace.h @@ -143,6 +143,22 @@ TRACE_EVENT(kvm_emulate_cp15_imp, __entry->CRm, __entry->Op2) ); +TRACE_EVENT(kvm_wfi, + TP_PROTO(unsigned long vcpu_pc), + TP_ARGS(vcpu_pc), + + TP_STRUCT__entry( + __field( unsigned long, vcpu_pc ) + ), + + TP_fast_assign( + __entry->vcpu_pc = vcpu_pc; + ), + + TP_printk("guest executed wfi at: 0x%08lx", __entry->vcpu_pc) +); + + #endif /* _TRACE_KVM_H */ #undef TRACE_INCLUDE_PATH