Hello Wei Huang,
The patch 25462f7f5295: "KVM: x86/vPMU: Define kvm_pmu_ops to support
vPMU function dispatch" from Jun 19, 2015, leads to the following
static checker warning:
arch/x86/kvm/pmu_intel.c:297 intel_pmu_refresh()
warn: potential left shift more than type allows '0-32'
arch/x86/kvm/pmu_intel.c
277 pmu->version = eax.split.version_id;
278 if (!pmu->version)
279 return;
280
281 pmu->nr_arch_gp_counters = min_t(int, eax.split.num_counters,
282 INTEL_PMC_MAX_GENERIC);
^^^^^^^^^^^^^^^^^^^^^
We cap ->nr_arch_gp_counters at 32.
283 pmu->counter_bitmask[KVM_PMC_GP] = ((u64)1 << eax.split.bit_width) - 1;
284 pmu->available_event_types = ~entry->ebx &
285 ((1ull << eax.split.mask_length) - 1);
286
287 if (pmu->version == 1) {
288 pmu->nr_arch_fixed_counters = 0;
289 } else {
290 pmu->nr_arch_fixed_counters =
291 min_t(int, edx.split.num_counters_fixed,
292 INTEL_PMC_MAX_FIXED);
293 pmu->counter_bitmask[KVM_PMC_FIXED] =
294 ((u64)1 << edx.split.bit_width_fixed) - 1;
295 }
296
297 pmu->global_ctrl = ((1 << pmu->nr_arch_gp_counters) - 1) |
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Potential shift wrapping bug.
298 (((1ull << pmu->nr_arch_fixed_counters) - 1) << INTEL_PMC_IDX_FIXED);
299 pmu->global_ctrl_mask = ~pmu->global_ctrl;
300
301 entry = kvm_find_cpuid_entry(vcpu, 7, 0);
302 if (entry &&
303 (boot_cpu_has(X86_FEATURE_HLE) || boot_cpu_has(X86_FEATURE_RTM)) &&
304 (entry->ebx & (X86_FEATURE_HLE|X86_FEATURE_RTM)))
305 pmu->reserved_bits ^= HSW_IN_TX|HSW_IN_TX_CHECKPOINTED;
regards,
dan carpenter
