From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Wang Subject: Re: [PATCH V2 2/6] kvm: detect assigned device via irqbypass manager Date: Mon, 20 Jul 2020 12:19:37 +0800 Message-ID: References: <1594898629-18790-1-git-send-email-lingshan.zhu@intel.com> <1594898629-18790-3-git-send-email-lingshan.zhu@intel.com> <20200717120821.3c2a56db@x1.home> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20200717120821.3c2a56db@x1.home> Content-Language: en-US Sender: netdev-owner@vger.kernel.org To: Alex Williamson , Zhu Lingshan Cc: mst@redhat.com, pbonzini@redhat.com, sean.j.christopherson@intel.com, wanpengli@tencent.com, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, kvm@vger.kernel.org List-Id: virtualization@lists.linuxfoundation.org On 2020/7/18 上午2:08, Alex Williamson wrote: > On Thu, 16 Jul 2020 19:23:45 +0800 > 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. >> >> 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 >> Suggested-by: Jason Wang >> --- >> 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