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Sandipan Das
e09465aecc
commit49ff3b4aecupstream. On AMD and Hygon platforms, the local APIC does not automatically set the mask bit of the LVTPC register when handling a PMI and there is no need to clear it in the kernel's PMI handler. For guests, the mask bit is currently set by kvm_apic_local_deliver() and unless it is cleared by the guest kernel's PMI handler, PMIs stop arriving and break use-cases like sampling with perf record. This does not affect non-PerfMonV2 guests because PMIs are handled in the guest kernel by x86_pmu_handle_irq() which always clears the LVTPC mask bit irrespective of the vendor. Before: $ perf record -e cycles:u true [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.001 MB perf.data (1 samples) ] After: $ perf record -e cycles:u true [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.002 MB perf.data (19 samples) ] Fixes:a16eb25b09("KVM: x86: Mask LVTPC when handling a PMI") Cc: stable@vger.kernel.org Signed-off-by: Sandipan Das <sandipan.das@amd.com> Reviewed-by: Jim Mattson <jmattson@google.com> [sean: use is_intel_compatible instead of !is_amd_or_hygon()] Signed-off-by: Sean Christopherson <seanjc@google.com> Message-ID: <20240405235603.1173076-3-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>