KVM: selftests: Trigger L2->L1 exits stress save+restore and #PF test

Extend the testing coverage in L2 by forcing a nested VM-Exit from L2 to
L1 right after restore on every other iteration. Forcing a nested
VM-Exit while L0 has control (e.g. without explicitly running L2 and
making a hypercall) is valuable, as it often happens during live
migration (e.g. L1 timer interrupt fires by the time the VM lands on the
destination).

To force the nested VM-Exit inject a #UD in to the saved vCPU state, and
intercept #UD from L1.

With this change, the test reliably reproduces the CR2 bug fixed by
commit 5c247d08bc81 ("KVM: nSVM: Use vcpu->arch.cr2 when updating vmcb12
on nested #VMEXIT") -- at least on Milan, Genoa, and Turin CPUs.

Assisted-by: Gemini:gemini-3.1-pro
Signed-off-by: Yosry Ahmed <yosry@kernel.org>
Link: https://patch.msgid.link/20260728174232.2423257-14-yosry@kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>

0 files changed, 0 insertions, 0 deletions