ACK: [SRU][B/F:linux-kvm][PATCH v3 0/1] UBUNTU: [Config] kvm: Add support for modifying LDT

[Cory Todd]

On Thu, Mar 30, 2023 at 10:06:47AM +0200, Roxana Nicolescu wrote:
> BugLink: https://bugs.launchpad.net/bugs/2009442
> 
> SRU Justification:
> 
> [Impact]
> bionic/focal linux-kvm failure in glibc autopkgtest
> 
> FAIL: misc/tst-bz21269
> original exit status 1
> error: ../sysdeps/unix/sysv/linux/i386/tst-bz21269.c:55:
> not true: syscall (SYS_modify_ldt, 1, ptr, bytecount) == 0
> error: 1 test failures
> 
> Syscall modify_ldt is not enabled because
> CONFIG_MODIFY_LDT_SYSCALL=n for bionic/focal-kvm,
> even though generic and newer versions (even kvm derivativatives)
> have it enabled.
> 
> [Fix]
> Custom patch to bionic/focal-kvm to enable CONFIG_MODIFY_LDT_SYSCALL.
> 
> [Test Plan]
> Built on cbd and tested autopkgtest glibc locally in a vm.
> 
> [Where problems could occur]
> 1. Regression probability is pretty low, we are adding functionality
> not previously present but looking at jammy this test is fine.
> 2. Enabling this adds a small overhead to context switches
> and increases the low level kernel attack surface.
> 
> v2:
> 1. Modified the annotation file.
> 2. Set CONFIG_X86_16BIT=n to avoid getting the prompt that interrupts
> the build process.
> 
> v3:
> Corrected annotation option for bionic.
> 
> Roxana Nicolescu (1):
>   UBUNTU: [Config] kvm: Add support for modifying LDT
> --
> 2.34.1
> 
Acked-by: Cory Todd <cory.todd at canonical.com>

- corytodd