ACK: [SRU][N:linux-gcp/O:linux-gcp][PATCH 0/2] Fix HLT logic execution for TDX VMs

[Kevin Becker]

On Mon, Jun 9, 2025 at 6:01 PM Ian Whitfield
<ian.whitfield at canonical.com> wrote:
>
> BugLink: https://bugs.launchpad.net/bugs/2112602
>
> [Impact]
> Google has requested a backport of the following commits:
> 22cc5ca5de52 ("x86/paravirt: Move halt paravirt calls under CONFIG_PARAVIRT")
> 9f98a4f4e721 ("x86/tdx: Fix arch_safe_halt() execution for TDX VMs")
> Targets include 6.8 onwards.
>
> [Fix]
> Noble required both patches, Oracular required just the first patch. Kernels
> after Oracular have already received these patches via stable updates.
>
> Upstream stable backports were used for both patches, and these applied cleanly.
>
> [Test plan]
> Compile and boot test. Verification on Google's side is optional as this is a
> fairly isolated backport.
>
> [Where problems could occur]
> This fix affects TDX guest VMs which call the HLT instruction. An issue with
> this fix would be visible to the user as unexpected #VEs (virtualization
> exceptions) or unexpected interrupt behavior in their TDX guest VM.
>
> [Other]
> SF #00412211
>
> Kirill A. Shutemov (1):
>   x86/paravirt: Move halt paravirt calls under CONFIG_PARAVIRT
>
> Vishal Annapurve (1):
>   x86/tdx: Fix arch_safe_halt() execution for TDX VMs
>
>  arch/x86/Kconfig                      |  1 +
>  arch/x86/coco/tdx/tdx.c               | 26 ++++++++++++++++-
>  arch/x86/include/asm/irqflags.h       | 40 +++++++++++++++------------
>  arch/x86/include/asm/paravirt.h       | 20 +++++++-------
>  arch/x86/include/asm/paravirt_types.h |  3 +-
>  arch/x86/include/asm/tdx.h            |  4 +--
>  arch/x86/kernel/paravirt.c            | 14 ++++++----
>  arch/x86/kernel/process.c             |  2 +-
>  8 files changed, 70 insertions(+), 40 deletions(-)
>

Acked-by: Kevin Becker <kevin.becker at canonical.com>