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KVM: x86: Clarify PMU related features bit manipulation 

kvm_pmu_cpuid_update makes a lot of bit manuiplation operations, when in fact
there are already unions that can be used instead. Changing the bit
manipulation to the union for clarity. This patch does not change the
functionality.

Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Nadav Amit 2014-08-20 13:25:52 +03:00 committed by Paolo Bonzini
parent a32e84594d
commit d27aa7f15c
1 changed files with 14 additions and 10 deletions
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24
arch/x86/kvm/pmu.c
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@ -15,6 +15,7 @@
#include <linux/types.h>
#include <linux/kvm_host.h>
#include <linux/perf_event.h>
#include <asm/perf_event.h>
#include "x86.h"
#include "cpuid.h"
#include "lapic.h"
@ -463,7 +464,8 @@ void kvm_pmu_cpuid_update(struct kvm_vcpu *vcpu)
{
struct kvm_pmu *pmu = &vcpu->arch.pmu;
struct kvm_cpuid_entry2 *entry;
unsigned bitmap_len;
union cpuid10_eax eax;
union cpuid10_edx edx;
pmu->nr_arch_gp_counters = 0;
pmu->nr_arch_fixed_counters = 0;
@ -475,25 +477,27 @@ void kvm_pmu_cpuid_update(struct kvm_vcpu *vcpu)
entry = kvm_find_cpuid_entry(vcpu, 0xa, 0);
if (!entry)
return;
eax.full = entry->eax;
edx.full = entry->edx;
pmu->version = entry->eax & 0xff;
pmu->version = eax.split.version_id;
if (!pmu->version)
return;
pmu->nr_arch_gp_counters = min((int)(entry->eax >> 8) & 0xff,
INTEL_PMC_MAX_GENERIC);
pmu->counter_bitmask[KVM_PMC_GP] =
((u64)1 << ((entry->eax >> 16) & 0xff)) - 1;
bitmap_len = (entry->eax >> 24) & 0xff;
pmu->available_event_types = ~entry->ebx & ((1ull << bitmap_len) - 1);
pmu->nr_arch_gp_counters = min_t(int, eax.split.num_counters,
INTEL_PMC_MAX_GENERIC);
pmu->counter_bitmask[KVM_PMC_GP] = ((u64)1 << eax.split.bit_width) - 1;
pmu->available_event_types = ~entry->ebx &
((1ull << eax.split.mask_length) - 1);
if (pmu->version == 1) {
pmu->nr_arch_fixed_counters = 0;
} else {
pmu->nr_arch_fixed_counters = min((int)(entry->edx & 0x1f),
pmu->nr_arch_fixed_counters =
min_t(int, edx.split.num_counters_fixed,
INTEL_PMC_MAX_FIXED);
pmu->counter_bitmask[KVM_PMC_FIXED] =
((u64)1 << ((entry->edx >> 5) & 0xff)) - 1;
((u64)1 << edx.split.bit_width_fixed) - 1;
}
pmu->global_ctrl = ((1 << pmu->nr_arch_gp_counters) - 1) |