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Message-ID: <1563437710-30756-1-git-send-email-yuzenghui@huawei.com>
Date: Thu, 18 Jul 2019 08:15:10 +0000
From: Zenghui Yu <yuzenghui@...wei.com>
To: <maz@...nel.org>, <kvmarm@...ts.cs.columbia.edu>,
<linux-arm-kernel@...ts.infradead.org>
CC: <marc.zyngier@....com>, <james.morse@....com>,
<julien.thierry@....com>, <suzuki.poulose@....com>,
<julien.thierry.kdev@...il.com>, <linux-kernel@...r.kernel.org>,
<wanghaibin.wang@...wei.com>, <andrew.murray@....com>,
Zenghui Yu <yuzenghui@...wei.com>
Subject: [PATCH v2] KVM: arm/arm64: Introduce kvm_pmu_vcpu_init() to setup PMU counter idx
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: 80f393a23be6 ("KVM: arm/arm64: Support chained PMU counters")
Suggested-by: Andrew Murray <andrew.murray@....com>
Suggested-by: Julien Thierry <julien.thierry@....com>
Cc: Marc Zyngier <maz@...nel.org>
Signed-off-by: Zenghui Yu <yuzenghui@...wei.com>
---
Changes since v1:
- Introduce kvm_pmu_vcpu_init() in vcpu's creation time, move the
assignment of pmc->idx into it.
- Thus change the subject. The old one is "KVM: arm/arm64: Assign
pmc->idx before kvm_pmu_stop_counter()".
Julien, I haven't collected your Acked-by into this version. If you're
still happy with the change, please Ack again. Thanks!
include/kvm/arm_pmu.h | 2 ++
virt/kvm/arm/arm.c | 2 ++
virt/kvm/arm/pmu.c | 18 +++++++++++++++---
3 files changed, 19 insertions(+), 3 deletions(-)
diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
index 16c769a..6db0304 100644
--- a/include/kvm/arm_pmu.h
+++ b/include/kvm/arm_pmu.h
@@ -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) {}
diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
index f645c0f..c704fa6 100644
--- a/virt/kvm/arm/arm.c
+++ b/virt/kvm/arm/arm.c
@@ -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);
diff --git a/virt/kvm/arm/pmu.c b/virt/kvm/arm/pmu.c
index 3dd8238..362a018 100644
--- a/virt/kvm/arm/pmu.c
+++ b/virt/kvm/arm/pmu.c
@@ -215,6 +215,20 @@ static void kvm_pmu_stop_counter(struct kvm_vcpu *vcpu, struct kvm_pmc *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);
}
--
1.8.3.1
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