NVMe show-regs command forcibly reboots ARM-based VM

[Chengen Du]

[Impact]
The ARM-based VM will reboot after executing the 'nvme show-regs' command.

[Fix]
There is an upstream commit that fixed this issue:

commit fa5a46cc25b884a61a14f06e6693373bcefff29d
Author: Oliver Upton <email address hidden>
Date: Thu Jul 4 19:59:26 2024 +0200

    common.h: Avoid using unsupported load/store instructions in arm64 VMs

    Using nvme show-regs within a VM on arm64 can sometimes lead to VM
    termination.

    To answer why this happens: one of the deficiencies of the Arm
    architecture is that there exists a range of load/store instructions
    that have insufficient decode information for traps taken to the
    hypervisor. KVM, for example, may raise an external abort or outright
    terminate the VM depending on the configuration.

    This is a known problem on the kernel side, and is fixed by using
    assembly MMIO accessors w/ 'safe' load/store instructions. So do
    exactly that, providing arm64-specific accessors and falling back to
    plain old volatile pointer accesses for other architectures.

    Reported-by: William Butler <email address hidden>
    Signed-off-by: Oliver Upton <email address hidden>

[Test Plan]
Execute the command 'nvme show-regs /dev/nvme0' to confirm if it functions correctly.

[Where problems could occur]
The patch fixes the issue by using assembly code to access MMIO on ARM, while keeping the original approach on other platforms. If the patch encounters any issues, it will only impact the functionality of displaying register data on ARM-based platforms.

[Chengen Du (chengendu)]

Debdiff for Focal

[Chengen Du (chengendu)]

Debdiff for Jammy

[Chengen Du (chengendu)]

Debdiff for Mantic

[Chengen Du (chengendu)]

Debdiff for Noble

[Chengen Du (chengendu)]

Debdiff for Oracular

[Ubuntu Foundations Team Bug Bot (crichton)]

The attachment "lp2072381_nvme-cli_focal.debdiff" seems to be a debdiff. The ubuntu-sponsors team has been subscribed to the bug report so that they can review and hopefully sponsor the debdiff. If the attachment isn't a patch, please remove the "patch" flag from the attachment, remove the "patch" tag, and if you are member of the ~ubuntu-sponsors, unsubscribe the team.

[This is an automated message performed by a Launchpad user owned by ~brian-murray, for any issue please contact him.]