| Message ID | 20211105192101.3862492-5-maz@kernel.org (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | KVM: Turn the vcpu array into an xarray | expand |
On Fri, Nov 05, 2021, Marc Zyngier wrote: > As we are about to change the way vcpus are allocated, mandate > the use of kvm_get_vcpu() instead of open-coding the access. > > Signed-off-by: Marc Zyngier <maz@kernel.org> > --- > arch/x86/kvm/vmx/posted_intr.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/vmx/posted_intr.c b/arch/x86/kvm/vmx/posted_intr.c > index 5f81ef092bd4..82a49720727d 100644 > --- a/arch/x86/kvm/vmx/posted_intr.c > +++ b/arch/x86/kvm/vmx/posted_intr.c > @@ -272,7 +272,7 @@ int pi_update_irte(struct kvm *kvm, unsigned int host_irq, uint32_t guest_irq, > > if (!kvm_arch_has_assigned_device(kvm) || > !irq_remapping_cap(IRQ_POSTING_CAP) || > - !kvm_vcpu_apicv_active(kvm->vcpus[0])) > + !kvm_vcpu_apicv_active(kvm_get_vcpu(kvm, 0))) Huh. The existing code is decidedly odd. I think it might even be broken, as it's not obvious that vCPU0 _must_ be created when e.g. kvm_arch_irq_bypass_add_producer() is called. An equivalent, safe check would be: diff --git a/arch/x86/kvm/vmx/posted_intr.c b/arch/x86/kvm/vmx/posted_intr.c index 5f81ef092bd4..a3100591a9ca 100644 --- a/arch/x86/kvm/vmx/posted_intr.c +++ b/arch/x86/kvm/vmx/posted_intr.c @@ -272,7 +272,7 @@ int pi_update_irte(struct kvm *kvm, unsigned int host_irq, uint32_t guest_irq, if (!kvm_arch_has_assigned_device(kvm) || !irq_remapping_cap(IRQ_POSTING_CAP) || - !kvm_vcpu_apicv_active(kvm->vcpus[0])) + !kvm_apicv_activated(kvm)) return 0; idx = srcu_read_lock(&kvm->irq_srcu); But I think even that is flawed, as APICv can be dynamically deactivated and re-activated while the VM is running, and I don't see a path that re-updates the IRTE when APICv is re-activated. So I think a more conservative check is needed, e.g. diff --git a/arch/x86/kvm/vmx/posted_intr.c b/arch/x86/kvm/vmx/posted_intr.c index 5f81ef092bd4..6cf5b2e86118 100644 --- a/arch/x86/kvm/vmx/posted_intr.c +++ b/arch/x86/kvm/vmx/posted_intr.c @@ -272,7 +272,7 @@ int pi_update_irte(struct kvm *kvm, unsigned int host_irq, uint32_t guest_irq, if (!kvm_arch_has_assigned_device(kvm) || !irq_remapping_cap(IRQ_POSTING_CAP) || - !kvm_vcpu_apicv_active(kvm->vcpus[0])) + !irqchip_in_kernel(kvm) || !enable_apicv) return 0; idx = srcu_read_lock(&kvm->irq_srcu); Paolo, am I missing something?
On 11/5/21 21:03, Sean Christopherson wrote: > But I think even that is flawed, as APICv can be dynamically deactivated and > re-activated while the VM is running, and I don't see a path that re-updates > the IRTE when APICv is re-activated. So I think a more conservative check is > needed, e.g. > > diff --git a/arch/x86/kvm/vmx/posted_intr.c b/arch/x86/kvm/vmx/posted_intr.c > index 5f81ef092bd4..6cf5b2e86118 100644 > --- a/arch/x86/kvm/vmx/posted_intr.c > +++ b/arch/x86/kvm/vmx/posted_intr.c > @@ -272,7 +272,7 @@ int pi_update_irte(struct kvm *kvm, unsigned int host_irq, uint32_t guest_irq, > > if (!kvm_arch_has_assigned_device(kvm) || > !irq_remapping_cap(IRQ_POSTING_CAP) || > - !kvm_vcpu_apicv_active(kvm->vcpus[0])) > + !irqchip_in_kernel(kvm) || !enable_apicv) > return 0; > > idx = srcu_read_lock(&kvm->irq_srcu); What happens then if pi_pre_block is called and the IRTE denotes a posted interrupt? I might be wrong, but it seems to me that you have to change all of the occurrences this way. As soon as enable_apicv is set, you need to go through the POSTED_INTR_WAKEUP_VECTOR just in case. Paolo
On Tue, Nov 16, 2021, Paolo Bonzini wrote: > On 11/5/21 21:03, Sean Christopherson wrote: > > But I think even that is flawed, as APICv can be dynamically deactivated and > > re-activated while the VM is running, and I don't see a path that re-updates > > the IRTE when APICv is re-activated. So I think a more conservative check is > > needed, e.g. > > > > diff --git a/arch/x86/kvm/vmx/posted_intr.c b/arch/x86/kvm/vmx/posted_intr.c > > index 5f81ef092bd4..6cf5b2e86118 100644 > > --- a/arch/x86/kvm/vmx/posted_intr.c > > +++ b/arch/x86/kvm/vmx/posted_intr.c > > @@ -272,7 +272,7 @@ int pi_update_irte(struct kvm *kvm, unsigned int host_irq, uint32_t guest_irq, > > > > if (!kvm_arch_has_assigned_device(kvm) || > > !irq_remapping_cap(IRQ_POSTING_CAP) || > > - !kvm_vcpu_apicv_active(kvm->vcpus[0])) > > + !irqchip_in_kernel(kvm) || !enable_apicv) > > return 0; > > > > idx = srcu_read_lock(&kvm->irq_srcu); > > What happens then if pi_pre_block is called and the IRTE denotes a posted > interrupt? > > I might be wrong, but it seems to me that you have to change all of the > occurrences this way. As soon as enable_apicv is set, you need to go > through the POSTED_INTR_WAKEUP_VECTOR just in case. Sorry, I didn't grok that at all. All occurences of what?
On 11/16/21 17:07, Sean Christopherson wrote: >>> if (!kvm_arch_has_assigned_device(kvm) || >>> !irq_remapping_cap(IRQ_POSTING_CAP) || >>> - !kvm_vcpu_apicv_active(kvm->vcpus[0])) >>> + !irqchip_in_kernel(kvm) || !enable_apicv) >>> return 0; >>> >>> idx = srcu_read_lock(&kvm->irq_srcu); >> What happens then if pi_pre_block is called and the IRTE denotes a posted >> interrupt? >> >> I might be wrong, but it seems to me that you have to change all of the >> occurrences this way. As soon as enable_apicv is set, you need to go >> through the POSTED_INTR_WAKEUP_VECTOR just in case. > Sorry, I didn't grok that at all. All occurences of what? Of the !assigned-device || !VTd-PI || !kvm_vcpu_apicv_active(vcpu) checks. This way, CPUs are woken up correctly even if you have !kvm_vcpu_apicv_active(vcpu) but the IRTE is a posted-interrupt one. Paolo
diff --git a/arch/x86/kvm/vmx/posted_intr.c b/arch/x86/kvm/vmx/posted_intr.c index 5f81ef092bd4..82a49720727d 100644 --- a/arch/x86/kvm/vmx/posted_intr.c +++ b/arch/x86/kvm/vmx/posted_intr.c @@ -272,7 +272,7 @@ int pi_update_irte(struct kvm *kvm, unsigned int host_irq, uint32_t guest_irq, if (!kvm_arch_has_assigned_device(kvm) || !irq_remapping_cap(IRQ_POSTING_CAP) || - !kvm_vcpu_apicv_active(kvm->vcpus[0])) + !kvm_vcpu_apicv_active(kvm_get_vcpu(kvm, 0))) return 0; idx = srcu_read_lock(&kvm->irq_srcu);
As we are about to change the way vcpus are allocated, mandate the use of kvm_get_vcpu() instead of open-coding the access. Signed-off-by: Marc Zyngier <maz@kernel.org> --- arch/x86/kvm/vmx/posted_intr.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)