Ben-Ami Yassour wrote:
> On Tue, 2008-08-05 at 22:46 +0800, Han, Weidong wrote:
>> Ben-Ami Yassour wrote:
>>> [Ben: fixed memory pinning]
>>>
>>> Signed-off-by: Kay, Allen M <[EMAIL PROTECTED]>
>>> Signed-off-by: Weidong Han <[EMAIL PROTECTED]>
>>> Signed-off-by: Ben-Ami Yassour <[EMAIL PROTECTED]>
>>> ---
>>> +
>>> +int kvm_iommu_map_guest(struct kvm *kvm,
>>> + struct kvm_assigned_dev_kernel *assigned_dev)
>>> +{
>>> + struct pci_dev *pdev = NULL;
>>> + int rc;
>>> +
>>> + printk(KERN_DEBUG "VT-d direct map: host bdf = %x:%x:%x\n",
>>> + assigned_dev->host_busnr,
>>> + PCI_SLOT(assigned_dev->host_devfn),
>>> + PCI_FUNC(assigned_dev->host_devfn));
>>> +
>>> + pdev = assigned_dev->dev;
>>> +
>>> + if (pdev == NULL) {
>>> + if (kvm->arch.intel_iommu_domain) {
>>> +
>> intel_iommu_domain_exit(kvm->arch.intel_iommu_domain);
>>> + kvm->arch.intel_iommu_domain = NULL;
>>> + }
>>> + return -ENODEV;
>>> + }
>>> +
>>> + kvm->arch.intel_iommu_domain = intel_iommu_domain_alloc(pdev); +
>>> + rc = kvm_iommu_map_memslots(kvm);
>>> + if (rc) {
>>> + kvm_iommu_unmap_memslots(kvm);
>>> + return rc;
>>> + }
>>> +
>>> + intel_iommu_detach_dev(kvm->arch.intel_iommu_domain,
>>> + pdev->bus->number, pdev->devfn);
>>
>> I think we should remove intel_iommu_detach_dev(), which detaches
>> device from iommu. If the device has been assigned to other domain
>> already, it should not be assigned to this domain. Maybe we need to
>> add a check whether the device has been assigned already.
>
> The problem is that in the generic VT-d code, the IOMMU is not updated
> when a device is detached, for example when the driver releases the
> device. Consider the following scenario:
> 1. load device driver on host
> 2. use device on host
> 3. unload device driver on host
> 4. Start KVM and assign the device to the guest.
>
> In this case there is no clearing of the IOMMU on step 3, and we get
> Vt-d failures (if we remove the above call).
>
I don't prefer this usage process. As we discussed before, there should
be a dummy driver to hide/unbind passthrough devices from host, only
these devices can be assigned. There should be a check whether device is
assignable or not. If the device is not hidden, or has been assigned to
other guest already, it cannot be assigned. At this point, I perfer to
remove the device driver before restart host to avoid loading driver
during booting.
Randy (Weidong)
> Regards,
> Ben
>
>>
>> Randy (Weidong)
>>
>>> +
>>> + rc = intel_iommu_context_mapping(kvm->arch.intel_iommu_domain,
>>> + pdev); + if (rc) {
>>> + printk(KERN_ERR "Domain context map for %s failed", +
>>> pci_name(pdev)); + return rc;
>>> + }
>>> + return 0;
>>> +}
>>> +
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