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KVM: arm/arm64: Introduce kvm_pmu_vcpu_init() to setup PMU counter index

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We use "pmc->idx" and the "chained" bitmap to determine if the pmc is
chained, in kvm_pmu_pmc_is_chained().  But idx might be uninitialized
(and random) when we doing this decision, through a KVM_ARM_VCPU_INIT
ioctl -> kvm_pmu_vcpu_reset(). And the test_bit() against this random
idx will potentially hit a KASAN BUG [1].

In general, idx is the static property of a PMU counter that is not
expected to be modified across resets, as suggested by Julien.  It
looks more reasonable if we can setup the PMU counter idx for a vcpu
in its creation time. Introduce a new function - kvm_pmu_vcpu_init()
for this basic setup. Oh, and the KASAN BUG will get fixed this way.

[1] https://www.spinics.net/lists/kvm-arm/msg36700.html

Fixes: 80f393a23b ("KVM: arm/arm64: Support chained PMU counters")
Suggested-by: Andrew Murray <andrew.murray@arm.com>
Suggested-by: Julien Thierry <julien.thierry@arm.com>
Acked-by: Julien Thierry <julien.thierry@arm.com>
Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This commit is contained in:
Zenghui Yu 2019-07-18 08:15:10 +00:00 committed by Marc Zyngier
parent 5f9e832c13
commit bca031e2c8
3 changed files with 19 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/kvm/arm_pmu.h
View File

@ -34,6 +34,7 @@ struct kvm_pmu {
u64 kvm_pmu_get_counter_value(struct kvm_vcpu *vcpu, u64 select_idx);
void kvm_pmu_set_counter_value(struct kvm_vcpu *vcpu, u64 select_idx, u64 val);
u64 kvm_pmu_valid_counter_mask(struct kvm_vcpu *vcpu);
void kvm_pmu_vcpu_init(struct kvm_vcpu *vcpu);
void kvm_pmu_vcpu_reset(struct kvm_vcpu *vcpu);
void kvm_pmu_vcpu_destroy(struct kvm_vcpu *vcpu);
void kvm_pmu_disable_counter_mask(struct kvm_vcpu *vcpu, u64 val);
@ -71,6 +72,7 @@ static inline u64 kvm_pmu_valid_counter_mask(struct kvm_vcpu *vcpu)
{
return 0;
}
static inline void kvm_pmu_vcpu_init(struct kvm_vcpu *vcpu) {}
static inline void kvm_pmu_vcpu_reset(struct kvm_vcpu *vcpu) {}
static inline void kvm_pmu_vcpu_destroy(struct kvm_vcpu *vcpu) {}
static inline void kvm_pmu_disable_counter_mask(struct kvm_vcpu *vcpu, u64 val) {}

2
virt/kvm/arm/arm.c
View File

@ -340,6 +340,8 @@ int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
/* Set up the timer */
kvm_timer_vcpu_init(vcpu);
kvm_pmu_vcpu_init(vcpu);
kvm_arm_reset_debug_ptr(vcpu);
return kvm_vgic_vcpu_init(vcpu);

18
virt/kvm/arm/pmu.c
View File

@ -214,6 +214,20 @@ static void kvm_pmu_stop_counter(struct kvm_vcpu *vcpu, struct kvm_pmc *pmc)
kvm_pmu_release_perf_event(pmc);
}
/**
* kvm_pmu_vcpu_init - assign pmu counter idx for cpu
* @vcpu: The vcpu pointer
*
*/
void kvm_pmu_vcpu_init(struct kvm_vcpu *vcpu)
{
int i;
struct kvm_pmu *pmu = &vcpu->arch.pmu;
for (i = 0; i < ARMV8_PMU_MAX_COUNTERS; i++)
pmu->pmc[i].idx = i;
}
/**
* kvm_pmu_vcpu_reset - reset pmu state for cpu
* @vcpu: The vcpu pointer
@ -224,10 +238,8 @@ void kvm_pmu_vcpu_reset(struct kvm_vcpu *vcpu)
int i;
struct kvm_pmu *pmu = &vcpu->arch.pmu;
for (i = 0; i < ARMV8_PMU_MAX_COUNTERS; i++) {
for (i = 0; i < ARMV8_PMU_MAX_COUNTERS; i++)
kvm_pmu_stop_counter(vcpu, &pmu->pmc[i]);
pmu->pmc[i].idx = i;
}
bitmap_zero(vcpu->arch.pmu.chained, ARMV8_PMU_MAX_COUNTER_PAIRS);
}