tree b5af604150706b9baf0aa59713cc70db60c3ffb2
parent 2cb2af7f53dba895c17ac7e7cf76b32839553e64
author Sean Christopherson <seanjc@google.com> 1709766113 -0800
committer Sean Christopherson <seanjc@google.com> 1717620089 -0700

x86/pmu: Add a PEBS test to verify the host LBRs aren't leaked to the guest

When using adaptive PEBS with LBR entries, verify that the LBR entries are
all '0'.  If KVM fails to context switch LBRs, e.g. when the guest isn't
using LBRs, as is the case in the pmu_pebs test, then adaptive PEBS can be
used to read the *host* LBRs as the CPU doesn't enforce the VMX MSR bitmaps
when generating PEBS records, i.e. ignores KVM's interception of reads to
LBR MSRs.

This testcase is best exercised by simultaneously utilizing LBRs in the
host, e.g. by running "perf record -b -e instructions", so that there is
non-zero data in the LBR MSRs.

Cc: Like Xu <like.xu.linux@gmail.com>
Cc: Mingwei Zhang <mizhang@google.com>
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Cc: Zhang Xiong <xiong.y.zhang@intel.com>
Cc: Lv Zhiyuan <zhiyuan.lv@intel.com>
Cc: Dapeng Mi <dapeng1.mi@intel.com>
Reviewed-by: Like Xu <likexu@tencent.com>
Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Tested-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Link: https://lore.kernel.org/r/20240306230153.786365-5-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>