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[79.180.10.140]) by smtp.gmail.com with ESMTPSA id i6sm11748360wrp.92.2020.07.13.03.52.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 13 Jul 2020 03:52:56 -0700 (PDT) Date: Mon, 13 Jul 2020 06:52:52 -0400 From: "Michael S. Tsirkin" To: Jason Wang Cc: Zhu Lingshan , alex.williamson@redhat.com, pbonzini@redhat.com, sean.j.christopherson@intel.com, wanpengli@tencent.com, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, netdev@vger.kernel.org, dan.daly@intel.com Subject: Re: [PATCH 2/7] kvm/vfio: detect assigned device via irqbypass manager Message-ID: <20200713065222-mutt-send-email-mst@kernel.org> References: <1594565366-3195-1-git-send-email-lingshan.zhu@intel.com> <1594565366-3195-2-git-send-email-lingshan.zhu@intel.com> <20200712170518-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Mon, Jul 13, 2020 at 04:13:35PM +0800, Jason Wang wrote: > > On 2020/7/13 上午5:06, Michael S. Tsirkin wrote: > > On Sun, Jul 12, 2020 at 10:49:21PM +0800, Zhu Lingshan wrote: > > > We used to detect assigned device via VFIO manipulated device > > > conters. This is less flexible consider VFIO is not the only > > > interface for assigned device. vDPA devices has dedicated > > > backed hardware as well. So this patch tries to detect > > > the assigned device 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 > > > > I think it's best to leave VFIO alone. Add appropriate APIs for VDPA, > > worry about converting existing users later. > > > > Just to make sure I understand, did you mean: > > 1) introduce another bridge for vDPA > > or > > 2) only detect vDPA via bypass manager? (we can leave VFIO code as is, then > the assigned device counter may increase/decrease twice if VFIO use irq > bypass manager which should be no harm). > > Thanks 2 is probably easier to justify. 1 would depend on the specific bridge proposed. > > > > > > --- > > > arch/x86/kvm/x86.c | 10 ++++++++-- > > > virt/kvm/vfio.c | 2 -- > > > 2 files changed, 8 insertions(+), 4 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/virt/kvm/vfio.c b/virt/kvm/vfio.c > > > index 8fcbc50..111da52 100644 > > > --- a/virt/kvm/vfio.c > > > +++ b/virt/kvm/vfio.c > > > @@ -226,7 +226,6 @@ static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg) > > > list_add_tail(&kvg->node, &kv->group_list); > > > kvg->vfio_group = vfio_group; > > > - kvm_arch_start_assignment(dev->kvm); > > > mutex_unlock(&kv->lock); > > > @@ -254,7 +253,6 @@ static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg) > > > continue; > > > list_del(&kvg->node); > > > - kvm_arch_end_assignment(dev->kvm); > > > #ifdef CONFIG_SPAPR_TCE_IOMMU > > > kvm_spapr_tce_release_vfio_group(dev->kvm, > > > kvg->vfio_group); > > > -- > > > 1.8.3.1