On Wed, 07 Jun 2023 14:09:53 -0700, Sean Christopherson wrote:
> Fix bugs in the LBRV tests, and try to make them a bit less painful to
> debug (goes from "excruitating" to just "awful"). The tests have been
> failing on our Milan systems for quite some time, but debugging them was
> painful and I wasn't sufficiently motivated until I wanted to clean up
> KVM's code :-/
>
> The Milan failures are due to AMD shoving a "mispredict" bit in the LBR
> records, i.e. the tests fail if the CPU mispredicts the branch being
> tested. Debug was especially difficult because the tests also neglected
> to setup a guest stack, i.e. adding debug code created a completely
> different failure that looked similar at first glance.
>
> [...]
Applied quickly to kvm-x86 next, as I'm OOO the rest of this week. I won't
send a pull request until sometime next week, e.g. if anyone objects to
putting the assertion macros in common util.h.
[1/6] x86: nSVM: Set up a guest stack in LBRV tests
https://github.com/kvm-x86/kvm-unit-tests/commit/bef5a3677b60
[2/6] lib: Expose a subset of VMX's assertion macros
https://github.com/kvm-x86/kvm-unit-tests/commit/11e5dc0f9ed4
[3/6] x86: Add defines for the various LBR record bit definitions
https://github.com/kvm-x86/kvm-unit-tests/commit/691df8f964df
[4/6] x86: nSVM: Ignore mispredict bit in LBR records
https://github.com/kvm-x86/kvm-unit-tests/commit/3ffa0914672e
[5/6] x86: nSVM: Replace check_dbgctl() with TEST_EXPECT_EQ() in LBRV test
https://github.com/kvm-x86/kvm-unit-tests/commit/d8849d8f3702
[6/6] x86: nSVM: Print out RIP and LBRs from VMCB if LBRV guest test fails
https://github.com/kvm-x86/kvm-unit-tests/commit/11c7d0604a50
--
https://github.com/kvm-x86/kvm-unit-tests/tree/next
