From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH 2/7] kvm/vfio: detect assigned device via irqbypass manager Date: Tue, 14 Jul 2020 05:03:22 -0400 Message-ID: <20200714050301-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> <20200713065222-mutt-send-email-mst@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: Content-Disposition: inline In-Reply-To: Sender: kvm-owner@vger.kernel.org To: "Zhu, Lingshan" Cc: Jason Wang , 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 List-Id: virtualization@lists.linuxfoundation.org On Tue, Jul 14, 2020 at 08:52:43AM +0800, Zhu, Lingshan wrote: > > On 7/13/2020 6:52 PM, Michael S. Tsirkin wrote: > > 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. > > Thanks Michael, so we should just drop changes in vfio, just increase / decrease > the counter in irq bypass manager. right? > > Thanks I don't see any issue with that. > > > --- > 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 >