Overview
About vulnerability
In the Linux kernel, the following vulnerability has been resolved:
iommu/vt-d: Disallow dirty tracking if incoherent page walk
Dirty page tracking relies on the IOMMU atomically updating the dirty bit in the paging-structure entry. For this operation to succeed, the paging- structure memory must be coherent between the IOMMU and the CPU. In another word, if the iommu page walk is incoherent, dirty page tracking doesn’t work.
The Intel VT-d specification, Section 3.10 “Snoop Behavior” states:
“Remapping hardware encountering the need to atomically update A/EA/D bits in a paging-structure entry that is not snooped will result in a non- recoverable fault.”
To prevent an IOMMU from being incorrectly configured for dirty page tracking when it is operating in an incoherent mode, mark SSADS as supported only when both ecap_slads and ecap_smpwc are supported.
Details
- Affected product:
- AlmaLinux 9.2 ESU , TuxCare 9.6 ESU
- Affected packages:
- kernel @ 5.14.0 (+1 more)
In the Linux kernel, the following vulnerability has been resolved:
iommu/vt-d: Disallow dirty tracking if incoherent page walk
Dirty page tracking relies on the IOMMU atomically updating the dirty bit in the paging-structure entry. For this operation to succeed, the paging- structure memory must be coherent between the IOMMU and the CPU. In another word, if the iommu page walk is incoherent, dirty page tracking doesn’t work.
The Intel VT-d specification, Section 3.10 “Snoop Behavior” states:
“Remapping hardware encountering the need to atomically update A/EA/D bits in a paging-structure entry that is not snooped will result in a non- recoverable fault.”
To prevent an IOMMU from being incorrectly configured for dirty page tracking when it is operating in an incoherent mode, mark SSADS as supported only when both ecap_slads and ecap_smpwc are supported.