| Message ID | 1594898629-18790-3-git-send-email-lingshan.zhu@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | IRQ offloading for vDPA | expand |
On 2020/7/16 下午7:23, Zhu Lingshan wrote: > vDPA devices has dedicated backed hardware like > passthrough-ed devices. Then it is possible to setup irq > offloading to vCPU for vDPA devices. Thus this patch tries to > manipulated assigned device counters via irqbypass manager. This part needs some tweak, e.g why assigned device could be detected through this way. > > We will increase/decrease the assigned device counter in kvm/x86. And you need explain why we don't need similar thing in other arch. Thanks > Both vDPA and VFIO would go through this code path. > > This code path only affect x86 for now. > > Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com> > Suggested-by: Jason Wang <jasowang@redhat.com> > --- > arch/x86/kvm/x86.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 00c88c2..20c07d3 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -10624,11 +10624,17 @@ int kvm_arch_irq_bypass_add_producer(struct irq_bypass_consumer *cons, > { > struct kvm_kernel_irqfd *irqfd = > container_of(cons, struct kvm_kernel_irqfd, consumer); > + int ret; > > irqfd->producer = prod; > + kvm_arch_start_assignment(irqfd->kvm); > + ret = kvm_x86_ops.update_pi_irte(irqfd->kvm, > + prod->irq, irqfd->gsi, 1); > + > + if (ret) > + kvm_arch_end_assignment(irqfd->kvm); > > - return kvm_x86_ops.update_pi_irte(irqfd->kvm, > - prod->irq, irqfd->gsi, 1); > + return ret; > } > > void kvm_arch_irq_bypass_del_producer(struct irq_bypass_consumer *cons,
On Thu, 16 Jul 2020 19:23:45 +0800 Zhu Lingshan <lingshan.zhu@intel.com> wrote: > vDPA devices has dedicated backed hardware like > passthrough-ed devices. Then it is possible to setup irq > offloading to vCPU for vDPA devices. Thus this patch tries to > manipulated assigned device counters via irqbypass manager. > > We will increase/decrease the assigned device counter in kvm/x86. > Both vDPA and VFIO would go through this code path. > > This code path only affect x86 for now. > > Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com> > Suggested-by: Jason Wang <jasowang@redhat.com> > --- > arch/x86/kvm/x86.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 00c88c2..20c07d3 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -10624,11 +10624,17 @@ int kvm_arch_irq_bypass_add_producer(struct irq_bypass_consumer *cons, > { > struct kvm_kernel_irqfd *irqfd = > container_of(cons, struct kvm_kernel_irqfd, consumer); > + int ret; > > irqfd->producer = prod; > + kvm_arch_start_assignment(irqfd->kvm); > + ret = kvm_x86_ops.update_pi_irte(irqfd->kvm, > + prod->irq, irqfd->gsi, 1); > + > + if (ret) > + kvm_arch_end_assignment(irqfd->kvm); > > - return kvm_x86_ops.update_pi_irte(irqfd->kvm, > - prod->irq, irqfd->gsi, 1); > + return ret; > } > > void kvm_arch_irq_bypass_del_producer(struct irq_bypass_consumer *cons, Why isn't there a matching end-assignment in the del_producer path? It seems this only goes one-way, what happens when a device is hot-unplugged from the VM or the device interrupt configuration changes. This will still break vfio if it's not guaranteed to be symmetric. Thanks, Alex
On 2020/7/18 上午2:08, Alex Williamson wrote: > On Thu, 16 Jul 2020 19:23:45 +0800 > Zhu Lingshan <lingshan.zhu@intel.com> wrote: > >> vDPA devices has dedicated backed hardware like >> passthrough-ed devices. Then it is possible to setup irq >> offloading to vCPU for vDPA devices. Thus this patch tries to >> manipulated assigned device counters via irqbypass manager. >> >> We will increase/decrease the assigned device counter in kvm/x86. >> Both vDPA and VFIO would go through this code path. >> >> This code path only affect x86 for now. >> >> Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com> >> Suggested-by: Jason Wang <jasowang@redhat.com> >> --- >> arch/x86/kvm/x86.c | 10 ++++++++-- >> 1 file changed, 8 insertions(+), 2 deletions(-) >> >> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c >> index 00c88c2..20c07d3 100644 >> --- a/arch/x86/kvm/x86.c >> +++ b/arch/x86/kvm/x86.c >> @@ -10624,11 +10624,17 @@ int kvm_arch_irq_bypass_add_producer(struct irq_bypass_consumer *cons, >> { >> struct kvm_kernel_irqfd *irqfd = >> container_of(cons, struct kvm_kernel_irqfd, consumer); >> + int ret; >> >> irqfd->producer = prod; >> + kvm_arch_start_assignment(irqfd->kvm); >> + ret = kvm_x86_ops.update_pi_irte(irqfd->kvm, >> + prod->irq, irqfd->gsi, 1); >> + >> + if (ret) >> + kvm_arch_end_assignment(irqfd->kvm); >> >> - return kvm_x86_ops.update_pi_irte(irqfd->kvm, >> - prod->irq, irqfd->gsi, 1); >> + return ret; >> } >> >> void kvm_arch_irq_bypass_del_producer(struct irq_bypass_consumer *cons, > > Why isn't there a matching end-assignment in the del_producer path? It > seems this only goes one-way, what happens when a device is > hot-unplugged from the VM or the device interrupt configuration changes. > This will still break vfio if it's not guaranteed to be symmetric. > Thanks, > > Alex Yes, we need add logic in the del_producer path. Thanks
On 7/17/2020 12:01 PM, Jason Wang wrote: > > On 2020/7/16 下午7:23, Zhu Lingshan wrote: >> vDPA devices has dedicated backed hardware like >> passthrough-ed devices. Then it is possible to setup irq >> offloading to vCPU for vDPA devices. Thus this patch tries to >> manipulated assigned device counters via irqbypass manager. > > > This part needs some tweak, e.g why assigned device could be detected > through this way. > > >> >> We will increase/decrease the assigned device counter in kvm/x86. > > > And you need explain why we don't need similar thing in other arch. > > Thanks OK Thanks! > > >> Both vDPA and VFIO would go through this code path. >> >> This code path only affect x86 for now. >> >> Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com> >> Suggested-by: Jason Wang <jasowang@redhat.com> >> --- >> arch/x86/kvm/x86.c | 10 ++++++++-- >> 1 file changed, 8 insertions(+), 2 deletions(-) >> >> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c >> index 00c88c2..20c07d3 100644 >> --- a/arch/x86/kvm/x86.c >> +++ b/arch/x86/kvm/x86.c >> @@ -10624,11 +10624,17 @@ int kvm_arch_irq_bypass_add_producer(struct >> irq_bypass_consumer *cons, >> { >> struct kvm_kernel_irqfd *irqfd = >> container_of(cons, struct kvm_kernel_irqfd, consumer); >> + int ret; >> irqfd->producer = prod; >> + kvm_arch_start_assignment(irqfd->kvm); >> + ret = kvm_x86_ops.update_pi_irte(irqfd->kvm, >> + prod->irq, irqfd->gsi, 1); >> + >> + if (ret) >> + kvm_arch_end_assignment(irqfd->kvm); >> - return kvm_x86_ops.update_pi_irte(irqfd->kvm, >> - prod->irq, irqfd->gsi, 1); >> + return ret; >> } >> void kvm_arch_irq_bypass_del_producer(struct irq_bypass_consumer >> *cons, >
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 00c88c2..20c07d3 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -10624,11 +10624,17 @@ int kvm_arch_irq_bypass_add_producer(struct irq_bypass_consumer *cons, { struct kvm_kernel_irqfd *irqfd = container_of(cons, struct kvm_kernel_irqfd, consumer); + int ret; irqfd->producer = prod; + kvm_arch_start_assignment(irqfd->kvm); + ret = kvm_x86_ops.update_pi_irte(irqfd->kvm, + prod->irq, irqfd->gsi, 1); + + if (ret) + kvm_arch_end_assignment(irqfd->kvm); - return kvm_x86_ops.update_pi_irte(irqfd->kvm, - prod->irq, irqfd->gsi, 1); + return ret; } void kvm_arch_irq_bypass_del_producer(struct irq_bypass_consumer *cons,
vDPA devices has dedicated backed hardware like passthrough-ed devices. Then it is possible to setup irq offloading to vCPU for vDPA devices. Thus this patch tries to manipulated assigned device counters via irqbypass manager. We will increase/decrease the assigned device counter in kvm/x86. Both vDPA and VFIO would go through this code path. This code path only affect x86 for now. Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com> Suggested-by: Jason Wang <jasowang@redhat.com> --- arch/x86/kvm/x86.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)