CVE-2021-47187

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> arm64: dts: qcom: msm8998: Fix CPU/L2 idle state latency and residency<br /> <br /> The entry/exit latency and minimum residency in state for the idle<br /> states of MSM8998 were ..bad: first of all, for all of them the<br /> timings were written for CPU sleep but the min-residency-us param<br /> was miscalculated (supposedly, while porting this from downstream);<br /> Then, the power collapse states are setting PC on both the CPU<br /> cluster *and* the L2 cache, which have different timings: in the<br /> specific case of L2 the times are higher so these ones should be<br /> taken into account instead of the CPU ones.<br /> <br /> This parameter misconfiguration was not giving particular issues<br /> because on MSM8998 there was no CPU scaling at all, so cluster/L2<br /> power collapse was rarely (if ever) hit.<br /> When CPU scaling is enabled, though, the wrong timings will produce<br /> SoC unstability shown to the user as random, apparently error-less,<br /> sudden reboots and/or lockups.<br /> <br /> This set of parameters are stabilizing the SoC when CPU scaling is<br /> ON and when power collapse is frequently hit.