All hardware with VT-d/AMD-Vi has CMPXCHG16B support. Check this at
initialisation time, and otherwise refuse to use the IOMMU.
If the local APICs support x2APIC mode the IOMMU support for interrupt
remapping will be checked earlier using a specific helper. If no support
for CX16 is detected by that earlier hook disable the IOMMU at that point
and prevent further poking for CX16 later in the boot process, which would
also fail.
There's a possible corner case when running virtualized, and the underlying
hypervisor exposing an IOMMU but no CMPXCHG16B support. In which case
ignoring the IOMMU is fine, albeit the most natural would be for the
underlying hypervisor to also expose CMPXCHG16B support if an IOMMU is
available to the VM.
Note this change only introduces the checks, but doesn't remove the now
stale checks for CX16 support sprinkled in the IOMMU code. Further changes
will take care of that.
Suggested-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Teddy Astie <teddy.astie@vates.tech>
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Release-Acked-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
In many places of x86 HVM code, constants integer are used to indicate in what mode is
running the CPU (real, vm86, 16-bits, 32-bits, 64-bits). However, these constants are
are written directly as integer which hides the actual meaning of these modes.
This patch introduces X86_MODE_* macros and replace those occurences with it.
Signed-off-by: Teddy Astie <teddy.astie@vates.tech>
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Teddy Astie <teddy.astie@vates.tech>
If for some reason xmalloc() fails after having mapped the reserved
regions, an error is reported, but the regions remain mapped in the P2M.
Similarly if an error occurs during set_identity_p2m_entry() (except on
the first call), the partial mappings of the region would be retained
without being tracked anywhere, and hence without there being a way to
remove them again from the domain's P2M.
Move the setting up of the list entry ahead of trying to map the region.
In cases other than the first mapping failing, keep record of the full
region, such that a subsequent unmapping request can be properly torn
down.
To compensate for the potentially excess unmapping requests, don't log a
warning from p2m_remove_identity_entry() when there really was nothing
mapped at a given GFN.
This is XSA-460 / CVE-2024-31145.
Fixes: 2201b67b91 ("VT-d: improve RMRR region handling")
Fixes: c0e19d7c6c ("IOMMU: generalize VT-d's tracking of mapped RMRR regions")
Signed-off-by: Teddy Astie <teddy.astie@vates.tech>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Teddy Astie