[SRU Bionic/Focal 0/2] LP: #1940134/CVE-2021-3653 - L2 guest on AMD SVM

[Thadeu Lima de Souza Cascardo]

This patchset reverts the original fix for CVE-2021-3653, which showed the
regression, and applied the fixed version that ended up upstream. The
regression only showed on backports for kernels older than 5.8. And as the
backport was necessary, I picked up the upstream stable v5.4.y version, which
applied cleanly on both focal and bionic trees.

The end result has been built and tested on an AMD system, where I was able to
launch an L2 Linux guest inside an L1 Linux guest. Both versions were tested.

[Impact]
Users won't be able to run a Linux inside a Linux guest.

[Test case]
Launch an L1 guest with libvirt, then launch an L2 guest using qemu inside that
first/L1 guest.

[Potential regression]
There might be reduced performance due to vmexits for interrupt handling.

Maxim Levitsky (1):
  KVM: nSVM: avoid picking up unsupported bits from L2 in int_ctl
    (CVE-2021-3653)

Thadeu Lima de Souza Cascardo (1):
  UBUNTU: SAUCE: Revert "UBUNTU: SAUCE: KVM: nSVM: avoid picking up
    unsupported bits from L2 in int_ctl"

 arch/x86/kvm/svm.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

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2.30.2