Messages in this thread | ![/](/images/icornerl.gif) | | Date | Sun, 06 May 2012 18:34:14 +0300 | From | Avi Kivity <> | Subject | Re: [PATCH] kvm: Enable device LTR/OBFF capibility before doing guest device assignment |
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On 05/06/2012 06:24 PM, Xudong Hao wrote: > Enable device LTR/OBFF capibility before do device assignment, so that guest can benefit from them.
cc += Alex
> @@ -166,6 +166,10 @@ int kvm_assign_device(struct kvm *kvm, > if (pdev == NULL) > return -ENODEV; > > + /* Enable some device capibility before do device assignment, > + * so that guest can benefit from them. > + */ > + kvm_iommu_enable_dev_caps(pdev); > r = iommu_attach_device(domain, &pdev->dev);
Suppose we fail here. Do we need to disable_dev_caps()?
> if (r) { > printk(KERN_ERR "assign device %x:%x:%x.%x failed", > @@ -228,6 +232,7 @@ int kvm_deassign_device(struct kvm *kvm, > PCI_SLOT(assigned_dev->host_devfn), > PCI_FUNC(assigned_dev->host_devfn)); > > + kvm_iommu_disable_dev_caps(pdev); > return 0; > } > > @@ -351,3 +356,30 @@ int kvm_iommu_unmap_guest(struct kvm *kvm) > iommu_domain_free(domain); > return 0; > } > + > +static void kvm_iommu_enable_dev_caps(struct pci_dev *pdev) > +{ > + /* set default value */ > + unsigned long type = PCI_EXP_OBFF_SIGNAL_ALWAYS; > + int snoop_lat_ns = 1024, nosnoop_lat_ns = 1024;
Where does this magic number come from?
> + > + /* LTR(Latency tolerance reporting) allows devices to send > + * messages to the root complex indicating their latency > + * tolerance for snooped & unsnooped memory transactions. > + */ > + pci_enable_ltr(pdev); > + pci_set_ltr(pdev, snoop_lat_ns, nosnoop_lat_ns); > + > + /* OBFF (optimized buffer flush/fill), where supported, > + * can help improve energy efficiency by giving devices > + * information about when interrupts and other activity > + * will have a reduced power impact. > + */ > + pci_enable_obff(pdev, type); > +} > + > +static void kvm_iommu_disable_dev_caps(struct pci_dev *pdev) > +{ > + pci_disble_obff(pdev); > + pci_disble_ltr(pdev); > +}
Do we need to communicate something about these capabilities to the guest?
-- error compiling committee.c: too many arguments to function
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