[SRU][B/F:linux-kvm][PATCH v2 0/1] UBUNTU: [Config] kvm: Add support for modifying LDT

[Roxana Nicolescu]

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.

Roxana Nicolescu (1):
  UBUNTU: [Config] kvm: Add support for modifying LDT

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2.34.1