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

Stefan Bader stefan.bader at
Tue Aug 17 10:23:22 UTC 2021

On 16.08.21 21:57, Thadeu Lima de Souza Cascardo wrote:
> 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(-)
Applied to focal:linux/master-next. Thanks.


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