[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [RFC v1 13/15] Update Posted-Interrupts Descriptor during vCPU scheduling
> -----Original Message----- > From: Andrew Cooper [mailto:andrew.cooper3@xxxxxxxxxx] > Sent: Friday, March 27, 2015 4:16 AM > To: Wu, Feng; xen-devel@xxxxxxxxxxxxx > Cc: Zhang, Yang Z; Tian, Kevin; keir@xxxxxxx; JBeulich@xxxxxxxx > Subject: Re: [Xen-devel] [RFC v1 13/15] Update Posted-Interrupts Descriptor > during vCPU scheduling > > On 25/03/15 12:31, Feng Wu wrote: > > The basic idea here is: > > 1. When vCPU's state is RUNSTATE_running, > > - set 'NV' to 'Notification Vector'. > > - Clear 'SN' to accpet PI. > > - set 'NDST' to the right pCPU. > > 2. When vCPU's state is RUNSTATE_blocked, > > - set 'NV' to 'Wake-up Vector', so we can wake up the > > related vCPU when posted-interrupt happens for it. > > - Clear 'SN' to accpet PI. > > 3. When vCPU's state is RUNSTATE_runnable/RUNSTATE_offline, > > - Set 'SN' to suppress non-urgent interrupts. > > (Current, we only support non-urgent interrupts) > > - Set 'NV' back to 'Notification Vector' if needed. > > > > Signed-off-by: Feng Wu <feng.wu@xxxxxxxxx> > > --- > > xen/arch/x86/hvm/vmx/vmx.c | 108 > +++++++++++++++++++++++++++++++++++++++++++++ > > xen/common/schedule.c | 3 ++ > > 2 files changed, 111 insertions(+) > > > > diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c > > index b30392c..6323bd6 100644 > > --- a/xen/arch/x86/hvm/vmx/vmx.c > > +++ b/xen/arch/x86/hvm/vmx/vmx.c > > @@ -1710,6 +1710,113 @@ static void vmx_handle_eoi(u8 vector) > > __vmwrite(GUEST_INTR_STATUS, status); > > } > > > > +static void vmx_pi_desc_update(struct vcpu *v, int new_state) > > +{ > > + struct pi_desc *pi_desc = &v->arch.hvm_vmx.pi_desc; > > + struct pi_desc old, new; > > + int old_state = v->runstate.state; > > + unsigned long flags; > > + > > + if ( !iommu_intpost ) > > + return; > > + > > + switch ( new_state ) > > + { > > + case RUNSTATE_runnable: > > + case RUNSTATE_offline: > > + /* > > + * We don't need to send notification event to a non-running > > + * vcpu, the interrupt information will be delivered to it before > > + * VM-ENTRY when the vcpu is scheduled to run next time. > > + */ > > + pi_set_sn(pi_desc); > > + > > + /* > > + * If the state is transferred from RUNSTATE_blocked, > > + * we should set 'NV' feild back to posted_intr_vector, > > + * so the Posted-Interrupts can be delivered to the vCPU > > + * by VT-d HW after it is scheduled to run. > > + */ > > + if ( old_state == RUNSTATE_blocked ) > > + { > > + do > > + { > > + old.control = new.control = pi_desc->control; > > + new.nv = posted_intr_vector; > > + } > > + while ( cmpxchg(&pi_desc->control, old.control, new.control) > > + != old.control ); > > + > > + /* > > + * Delete the vCPU from the related wakeup queue > > + * if we are resuming from blocked state > > + */ > > + spin_lock_irqsave(&per_cpu(blocked_vcpu_on_cpu_lock, > > + v->processor), flags); > > + list_del(&v->blocked_vcpu_list); > > The scheduler is perfectly able to change v->processor behind your back, > so your spinlocks are not protecting access to v->blocked_vcpu_list. > Oh, do you mean the following? 1) When we stored the vCPU in list of v->processor when vCPU is blocked. 2) Scheduler changes v->processor. 3) Oops, when vCPU is unblocked, we still use the old v->processor to find the vCPU. I think I can use the same method of what I am doing for KVM. I can introduce a new member v->blocked_cpu which stored the blocking pCPU info, then put vCPU in this list, and this variable is not changed by the scheduler. Thanks, Feng > ~Andrew > > > + spin_unlock_irqrestore(&per_cpu(blocked_vcpu_on_cpu_lock, > > + v->processor), flags); > > + } > > + break; > > + > > + case RUNSTATE_blocked: > > + /* > > + * The vCPU is blocked on the wait queue. > > + * Store the blocked vCPU on the list of the > > + * vcpu->wakeup_cpu, which is the destination > > + * of the wake-up notification event. > > + */ > > + spin_lock_irqsave(&per_cpu(blocked_vcpu_on_cpu_lock, > > + v->processor), flags); > > + list_add_tail(&v->blocked_vcpu_list, > > + &per_cpu(blocked_vcpu_on_cpu, v->processor)); > > + spin_unlock_irqrestore(&per_cpu(blocked_vcpu_on_cpu_lock, > > + v->processor), flags); > > + > > + do > > + { > > + old.control = new.control = pi_desc->control; > > + > > + /* > > + * We should not block the vCPU if > > + * an interrupt is posted for it. > > + */ > > + > > + if ( pi_test_on(&old) == 1 ) > > + { > > + tasklet_schedule(&v->vcpu_wakeup_tasklet); > > + return; > > + } > > + > > + pi_clear_sn(&new); > > + new.nv = pi_wakeup_vector; > > + } > > + while ( cmpxchg(&pi_desc->control, old.control, new.control) > > + != old.control ); > > + break; > > + > > + case RUNSTATE_running: > > + ASSERT( pi_test_sn(pi_desc) == 1 ); > > + > > + do > > + { > > + old.control = new.control = pi_desc->control; > > + if ( x2apic_enabled ) > > + new.ndst = cpu_physical_id(v->processor); > > + else > > + new.ndst = (cpu_physical_id(v->processor) << 8) & > 0xFF00; > > + > > + pi_clear_sn(&new); > > + } > > + while ( cmpxchg(&pi_desc->control, old.control, new.control) > > + != old.control ); > > + break; > > + > > + default: > > + break; > > + } > > +} > > + > > void vmx_hypervisor_cpuid_leaf(uint32_t sub_idx, > > uint32_t *eax, uint32_t *ebx, > > uint32_t *ecx, uint32_t *edx) > > @@ -1795,6 +1902,7 @@ static struct hvm_function_table __initdata > vmx_function_table = { > > .process_isr = vmx_process_isr, > > .deliver_posted_intr = vmx_deliver_posted_intr, > > .sync_pir_to_irr = vmx_sync_pir_to_irr, > > + .pi_desc_update = vmx_pi_desc_update, > > .handle_eoi = vmx_handle_eoi, > > .nhvm_hap_walk_L1_p2m = nvmx_hap_walk_L1_p2m, > > .hypervisor_cpuid_leaf = vmx_hypervisor_cpuid_leaf, > > diff --git a/xen/common/schedule.c b/xen/common/schedule.c > > index ef79847..acf3186 100644 > > --- a/xen/common/schedule.c > > +++ b/xen/common/schedule.c > > @@ -157,6 +157,9 @@ static inline void vcpu_runstate_change( > > v->runstate.state_entry_time = new_entry_time; > > } > > > > + if ( is_hvm_vcpu(v) && hvm_funcs.pi_desc_update ) > > + hvm_funcs.pi_desc_update(v, new_state); > > + > > v->runstate.state = new_state; > > } > > _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
|
Lists.xenproject.org is hosted with RackSpace, monitoring our |