[PATCH 0/1][kinetic/linux-azure] Azure: TDX enabled hyper-visors cause segfault

[Tim Gardner]

https://bugs.launchpad.net/bugs/2003714

SRU Justification

[Impact]

Microsoft TDX enabled hyper visors cause a segfault due to an upstream glibc bug. This can
be worked around with a kernel patch.

Issue Description:

When I start an Intel TDX Ubuntu 22.04 (or RHEL 9.0) guest on Hyper-V, the guest
always hits segfaults and can’t boot up. Here the kernel running in the guest is
the upstream kernel + my TDX patchset, or the 5.19.0-azure kernel + the same TDX patchset:

[Fix]

We confirmed the segfault also happens to TDX guests on the KVM hypervisor. After I
checked with more Intel folks, it turns out this is indeed a glibc bug
(https://sourceware.org/bugzilla/show_bug.cgi?id=28784), which has been fixed in the
upsteram glibc, but Ubuntu 22.04 and newer haven’t picked up the glibc fix yet.

I got a kernel side temporary workarouond from Intel:
https://github.com/dcui/tdx/commit/16218cf73491e867fd39c16c9e4b8aa926cbda68, which
is on the same existing branch “decui/upstream-kinetic-22.10/master-next/1209”.

[Test Plan]

Microsoft tested

[Where things could go wrong]

TDX is a new feature. Regressions are unlikely.