Mingwei Zhang b8525dced3 KVM: x86/pmu: Fix type length error when reading pmu->fixed_ctr_ctrl
commit 05519c86d6997cfb9bb6c82ce1595d1015b718dc upstream.

Use a u64 instead of a u8 when taking a snapshot of pmu->fixed_ctr_ctrl
when reprogramming fixed counters, as truncating the value results in KVM
thinking fixed counter 2 is already disabled (the bug also affects fixed
counters 3+, but KVM doesn't yet support those).  As a result, if the
guest disables fixed counter 2, KVM will get a false negative and fail to
reprogram/disable emulation of the counter, which can leads to incorrect
counts and spurious PMIs in the guest.

Fixes: 76d287b2342e ("KVM: x86/pmu: Drop "u8 ctrl, int idx" for reprogram_fixed_counter()")
Cc: stable@vger.kernel.org
Signed-off-by: Mingwei Zhang <mizhang@google.com>
Link: https://lore.kernel.org/r/20240123221220.3911317-1-mizhang@google.com
[sean: rewrite changelog to call out the effects of the bug]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-02-23 09:25:10 +01:00
..
2023-08-31 12:20:12 -07:00
2023-09-05 10:15:22 -07:00
2023-09-05 10:09:31 -07:00
2024-02-16 19:10:52 +01:00
2024-02-23 09:25:03 +01:00