mainline inclusion
from mainline-v5.18
commit 75189d1d
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5SDUS
CVE: NA

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

NMI-watchdog is one of the favorite features of kernel developers,
but it does not work in AMD guest even with vPMU enabled and worse,
the system misrepresents this capability via /proc.

This is a PMC emulation error. KVM does not pass the latest valid
value to perf_event in time when guest NMI-watchdog is running, thus
the perf_event corresponding to the watchdog counter will enter the
old state at some point after the first guest NMI injection, forcing
the hardware register PMC0 to be constantly written to 0x800000000001.

Meanwhile, the running counter should accurately reflect its new value
based on the latest coordinated pmc->counter (from vPMC's point of view)
rather than the value written directly by the guest.

Fixes: 168d918f ("KVM: x86: Adjust counter sample period after a wrmsr")
Reported-by: NDongli Cao <caodongli@kingsoft.com>
Signed-off-by: NLike Xu <likexu@tencent.com>
Reviewed-by: NYanan Wang <wangyanan55@huawei.com>
Tested-by: NYanan Wang <wangyanan55@huawei.com>
Reviewed-by: NJim Mattson <jmattson@google.com>
Message-Id: <20220409015226.38619-1-likexu@tencent.com>
Cc: stable@vger.kernel.org
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NYanan Wang <wangyanan55@huawei.com>
[Yanan Wang: Adapt the code to linux v4.19]
Reviewed-by: NZenghui Yu <yuzenghui@huawei.com>
Signed-off-by: NLaibin Qiu <qiulaibin@huawei.com>