mainline inclusion
from mainline-v5.12-rc1
commit 8e12911b
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I4NP0K
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8e12911b243e485f5e4c7c5fbc79cdf185728700

-------------------

When vcpu sets DEBUGCTLMSR_LBR in the MSR_IA32_DEBUGCTLMSR, the KVM handler
would create a guest LBR event which enables the callstack mode and none of
hardware counter is assigned. The host perf would schedule and enable this
event as usual but in an exclusive way.

The guest LBR event will be released when the vPMU is reset but soon,
the lazy release mechanism would be applied to this event like a vPMC.
Suggested-by: NAndi Kleen <ak@linux.intel.com>
Co-developed-by: NWei Wang <wei.w.wang@intel.com>
Signed-off-by: NWei Wang <wei.w.wang@intel.com>
Signed-off-by: NLike Xu <like.xu@linux.intel.com>
Reviewed-by: NAndi Kleen <ak@linux.intel.com>
Message-Id: <20210201051039.255478-6-like.xu@linux.intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NWangJian <wangjian161@huawei.com>
Reviewed-by: NWei Li <liwei391@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>