On 2019-07-23 09:17, Julien Thierry wrote:
Hi Zenghui,
On 18/07/2019 09:15, Zenghui Yu wrote:
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.mur...@arm.com>
Suggested-by: Julien Thierry <julien.thie...@arm.com>
Cc: Marc Zyngier <m...@kernel.org>
Signed-off-by: Zenghui Yu <yuzeng...@huawei.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!
Thanks for making the change. This looks good to me:
Acked-by: Julien Thierry <julien.thie...@arm.com>
Applied, thanks both.
M.
--
Jazz is not dead. It just smells funny...
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