Public bug reported:
SRU Justification:
[Impact]
Google has requested these upstream commits be applied in order to fix
bugs preventing the boot of 5.15 kernel instances on their Intel TDX
enabled infrastructure.
These patches aim to resolve problems with incorrect assessment of the
CPU's address width in bits on x86, mostly during boot.
[Fix]
Google recommended the patchset:
6890cb1ace35 x86/cpu/intel: Detect TME keyid bits before setting MTRR mask
registers
9a458198eba9 x86/cpu: Allow reducing x86_phys_bits during early_identify_cpu()
f6b980646b93 x86/mtrr: Remove physical address size calculation
And of these, only the first is already present in the Jammy 5.15 kernel.
[Test Plan]
Google reported inability to boot Focal images (which use this kernel)
on a specific configuration in a deployment zone where Intel TDX was
enabled. This patchset can be tested by booting a Jammy image on one
such machine (which uses the 6.8 kernel), installing this patched
kernel, and booting into it.
[Where problems could occur]
As these changes affect booting and the kernel's understanding of the
cpu, an error in the backporting of these patches could cause the user
to be unable to boot the kernel. Risk of an error is relatively low due
to the first patch applying cleanly and the second patch only needing
modification in the MTRR cleanup feature, which could be disabled with
a kernel command line parameter. If the fixes don't work, we would see
the kernel continue to not be bootable on TDX-enabled hosts.
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Affects: linux-gcp (Ubuntu)
Importance: Undecided
Status: New
** Affects: linux (Ubuntu Jammy)
Importance: Undecided
Assignee: Ian Whitfield (ijwhitfield)
Status: New
** Affects: linux-gcp (Ubuntu Jammy)
Importance: Undecided
Assignee: Ian Whitfield (ijwhitfield)
Status: New
** Also affects: linux-gcp (Ubuntu Jammy)
Importance: Undecided
Status: New
** Also affects: linux (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/2097811
Title:
Fix bugs preventing boot on Intel TDX-enabled hosts
Status in linux package in Ubuntu:
New
Status in linux-gcp package in Ubuntu:
New
Status in linux source package in Jammy:
New
Status in linux-gcp source package in Jammy:
New
Bug description:
SRU Justification:
[Impact]
Google has requested these upstream commits be applied in order to fix
bugs preventing the boot of 5.15 kernel instances on their Intel TDX
enabled infrastructure.
These patches aim to resolve problems with incorrect assessment of the
CPU's address width in bits on x86, mostly during boot.
[Fix]
Google recommended the patchset:
6890cb1ace35 x86/cpu/intel: Detect TME keyid bits before setting MTRR mask
registers
9a458198eba9 x86/cpu: Allow reducing x86_phys_bits during early_identify_cpu()
f6b980646b93 x86/mtrr: Remove physical address size calculation
And of these, only the first is already present in the Jammy 5.15 kernel.
[Test Plan]
Google reported inability to boot Focal images (which use this kernel)
on a specific configuration in a deployment zone where Intel TDX was
enabled. This patchset can be tested by booting a Jammy image on one
such machine (which uses the 6.8 kernel), installing this patched
kernel, and booting into it.
[Where problems could occur]
As these changes affect booting and the kernel's understanding of the
cpu, an error in the backporting of these patches could cause the user
to be unable to boot the kernel. Risk of an error is relatively low due
to the first patch applying cleanly and the second patch only needing
modification in the MTRR cleanup feature, which could be disabled with
a kernel command line parameter. If the fixes don't work, we would see
the kernel continue to not be bootable on TDX-enabled hosts.
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2097811/+subscriptions
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