As analyzed in https://bugzilla.kernel.org/show_bug.cgi?id=76331 we can have multiple DRHDs in a system and each may support different guest address widths. We can add a device behind a less capable DRHD to a domain so long as the lesser DRHD can map the existing domain page table. We should never increase the address width as a result of adding a device to the domain. The current code simply updates the width to the last added device. Change to keep it at the minumum DRHD width.
Reported-by: [email protected] Signed-off-by: Alex Williamson <[email protected]> Cc: David Woodhouse <[email protected]> --- drivers/iommu/intel-iommu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c index e68f44b..cd41d8d 100644 --- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -4276,7 +4276,7 @@ static int intel_iommu_attach_device(struct iommu_domain *domain, __func__, addr_width, dmar_domain->max_addr); return -EFAULT; } - dmar_domain->gaw = addr_width; + dmar_domain->gaw = min(addr_width, dmar_domain->gaw); /* * Knock out extra levels of page tables if necessary _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
