Messages in this thread Patch in this message | | | Subject | Re: [PATCH v5 7/7] iommu/vt-d: Differentiate relaxable and non relaxable RMRRs | From | Lu Baolu <> | Date | Wed, 29 May 2019 10:34:06 +0800 |
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Hi,
On 5/28/19 7:50 PM, Eric Auger wrote: > Now we have a new IOMMU_RESV_DIRECT_RELAXABLE reserved memory > region type, let's report USB and GFX RMRRs as relaxable ones. > > We introduce a new device_rmrr_is_relaxable() helper to check > whether the rmrr belongs to the relaxable category. > > This allows to have a finer reporting at IOMMU API level of > reserved memory regions. This will be exploitable by VFIO to > define the usable IOVA range and detect potential conflicts > between the guest physical address space and host reserved > regions. > > Signed-off-by: Eric Auger <eric.auger@redhat.com> > > --- > > v3 -> v4: > - introduce device_rmrr_is_relaxable and reshuffle the comments > --- > drivers/iommu/intel-iommu.c | 55 +++++++++++++++++++++++++++---------- > 1 file changed, 40 insertions(+), 15 deletions(-) > > diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c > index 9302351818ab..01c82f848470 100644 > --- a/drivers/iommu/intel-iommu.c > +++ b/drivers/iommu/intel-iommu.c > @@ -2920,6 +2920,36 @@ static bool device_has_rmrr(struct device *dev) > return false; > } > > +/* > + * device_rmrr_is_relaxable - Test whether the RMRR of this device > + * is relaxable (ie. is allowed to be not enforced under some conditions) > + * > + * @dev: device handle > + * > + * We assume that PCI USB devices with RMRRs have them largely > + * for historical reasons and that the RMRR space is not actively used post > + * boot. This exclusion may change if vendors begin to abuse it. > + * > + * The same exception is made for graphics devices, with the requirement that > + * any use of the RMRR regions will be torn down before assigning the device > + * to a guest. > + * > + * Return: true if the RMRR is relaxable > + */ > +static bool device_rmrr_is_relaxable(struct device *dev) > +{ > + struct pci_dev *pdev; > + > + if (!dev_is_pci(dev)) > + return false; > + > + pdev = to_pci_dev(dev); > + if (IS_USB_DEVICE(pdev) || IS_GFX_DEVICE(pdev)) > + return true; > + else > + return false; > +}
I know this is only code refactoring. But strictly speaking, the rmrr of any USB host device is ignorable only if quirk_usb_early_handoff() has been called. There, the control of USB host controller will be handed over from BIOS to OS and the corresponding SMI are disabled.
This function is registered in drivers/usb/host/pci-quirks.c
DECLARE_PCI_FIXUP_CLASS_FINAL(PCI_ANY_ID, PCI_ANY_ID, PCI_CLASS_SERIAL_USB, 8, quirk_usb_early_handoff);
and only get compiled if CONFIG_USB_PCI is enabled.
Hence, it's safer to say:
+#ifdef CONFIG_USB_PCI + if (IS_USB_DEVICE(pdev)) + return true; +#endif /* CONFIG_USB_PCI */
I am okay if we keep this untouched and make this change within a separated patch.
> + > /* > * There are a couple cases where we need to restrict the functionality of > * devices associated with RMRRs. The first is when evaluating a device for > @@ -2934,25 +2964,16 @@ static bool device_has_rmrr(struct device *dev) > * We therefore prevent devices associated with an RMRR from participating in > * the IOMMU API, which eliminates them from device assignment. > * > - * In both cases we assume that PCI USB devices with RMRRs have them largely > - * for historical reasons and that the RMRR space is not actively used post > - * boot. This exclusion may change if vendors begin to abuse it. > - * > - * The same exception is made for graphics devices, with the requirement that > - * any use of the RMRR regions will be torn down before assigning the device > - * to a guest. > + * In both cases, devices which have relaxable RMRRs are not concerned by this > + * restriction. See device_rmrr_is_relaxable comment. > */ > static bool device_is_rmrr_locked(struct device *dev) > { > if (!device_has_rmrr(dev)) > return false; > > - if (dev_is_pci(dev)) { > - struct pci_dev *pdev = to_pci_dev(dev); > - > - if (IS_USB_DEVICE(pdev) || IS_GFX_DEVICE(pdev)) > - return false; > - } > + if (device_rmrr_is_relaxable(dev)) > + return false; > > return true; > } > @@ -5494,6 +5515,7 @@ static void intel_iommu_get_resv_regions(struct device *device, > for_each_active_dev_scope(rmrr->devices, rmrr->devices_cnt, > i, i_dev) { > struct iommu_resv_region *resv; > + enum iommu_resv_type type; > size_t length; > > if (i_dev != device && > @@ -5501,9 +5523,12 @@ static void intel_iommu_get_resv_regions(struct device *device, > continue; > > length = rmrr->end_address - rmrr->base_address + 1; > + > + type = device_rmrr_is_relaxable(device) ? > + IOMMU_RESV_DIRECT_RELAXABLE : IOMMU_RESV_DIRECT; > + > resv = iommu_alloc_resv_region(rmrr->base_address, > - length, prot, > - IOMMU_RESV_DIRECT); > + length, prot, type); > if (!resv) > break; > >
Other looks good to me.
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Best regards, Baolu
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