AZL-50004

In the Linux kernel, the following vulnerability has been resolved:

perf/x86/intel: Limit the period on Haswell

Running the ltp test cve-2015-3290 concurrently reports the following warnings.

perfevents: irq loop stuck! WARNING: CPU: 31 PID: 32438 at arch/x86/events/intel/core.c:3174 intelpmuhandle_irq+0x285/0x370 Call Trace: <NMI> ? __warn+0xa4/0x220 ? intelpmuhandle_irq+0x285/0x370 ? __reportbug+0x123/0x130 ? intelpmuhandleirq+0x285/0x370 ? __reportbug+0x123/0x130 ? intelpmuhandleirq+0x285/0x370 ? reportbug+0x3e/0xa0 ? handlebug+0x3c/0x70 ? excinvalidop+0x18/0x50 ? asmexcinvalidop+0x1a/0x20 ? irqworkclaim+0x1e/0x40 ? intelpmuhandleirq+0x285/0x370 perfeventnmihandler+0x3d/0x60 nmihandle+0x104/0x330

Thanks to Thomas Gleixner's analysis, the issue is caused by the low initial period (1) of the frequency estimation algorithm, which triggers the defects of the HW, specifically erratum HSW11 and HSW143. (For the details, please refer https://lore.kernel.org/lkml/87plq9l5d2.ffs@tglx/)

The HSW11 requires a period larger than 100 for the INST_RETIRED.ALL event, but the initial period in the freq mode is 1. The erratum is the same as the BDM11, which has been supported in the kernel. A minimum period of 128 is enforced as well on HSW.

HSW143 is regarding that the fixed counter 1 may overcount 32 with the Hyper-Threading is enabled. However, based on the test, the hardware has more issues than it tells. Besides the fixed counter 1, the message 'interrupt took too long' can be observed on any counter which was armed with a period < 32 and two events expired in the same NMI. A minimum period of 32 is enforced for the rest of the events. The recommended workaround code of the HSW143 is not implemented. Because it only addresses the issue for the fixed counter. It brings extra overhead through extra MSR writing. No related overcounting issue has been reported so far.