[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v3] AMD/intremap: Prevent use of per-device vector maps until irq logic is fixed
>>> On 04.06.13 at 18:38, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote: > XSA-36 changed the default vector map mode from global to per-device. This is > because a global vector map does not prevent one PCI device from > impersonating > another and launching a DoS on the system. > > However, the per-device vector map logic is broken for devices with multiple > MSI-X vectors, which can either result in a failed ASSERT() or misprogramming > of a guests interrupt remapping tables. The core problem is not trivial to > fix. > > In an effort to get AMD systems back to a non-regressed state, introduce a > new > type of vector map called per-device-global. This uses per-device vector maps > in the IOMMU, but uses a single used_vector map for the core IRQ logic. > > This patch is intended to be removed as soon as the per-device logic is fixed > correctly. > > Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> Suravee, Jacob, no opinion on this at all? I've been talked into considering this acceptable (with a small coding style fixup, and with the question on the usefulness of the final warning message - imo redundant with the immediately preceding message that is being left untouched), with the strict expectation that this would get reverted right away after 4.3, with the multi-vector MSI series being the real fix to this (presumably allowing to drop the vector map stuff altogether). Jan > --- a/xen/drivers/passthrough/amd/pci_amd_iommu.c > +++ b/xen/drivers/passthrough/amd/pci_amd_iommu.c > @@ -223,8 +223,19 @@ int __init amd_iov_detect(void) > { > if ( amd_iommu_perdev_intremap ) > { > - printk("AMD-Vi: Enabling per-device vector maps\n"); > - opt_irq_vector_map = OPT_IRQ_VECTOR_MAP_PERDEV; > + /* Per-device vector map logic is broken for devices with > multiple > + * MSI-X interrupts (and would also be for multiple MSI, if Xen > + * supported it). > + * > + * Until this is fixed, use global vector tables as far as the > irq > + * logic is concerned to avoid the buggy behaviour of per-device > + * maps in map_domain_pirq(), and use per-device tables as far as > + * intremap code is concerned to avoid the security issue. > + */ > + printk(XENLOG_WARNING "AMD-Vi BUG: per-device vector map logic > is broken. " > + "Using per-device-global maps instead until a fix is > found\n"); > + > + opt_irq_vector_map = OPT_IRQ_VECTOR_MAP_GLOBAL; > } > else > { > @@ -235,6 +246,12 @@ int __init amd_iov_detect(void) > else > { > printk("AMD-Vi: Not overriding irq_vector_map setting\n"); > + > + if ( opt_irq_vector_map != OPT_IRQ_VECTOR_MAP_GLOBAL ) > + { > + printk(XENLOG_WARNING "AMD-Vi BUG: per-device vector map logic > is broken. " > + "Use irq_vector_map=global to work around."); > + } > } > if ( !amd_iommu_perdev_intremap ) > printk(XENLOG_WARNING "AMD-Vi: Using global interrupt remap table is > not recommended (see XSA-36)!\n"); _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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