Nicholas Piggin's on January 22, 2019 4:46 pm: > HV interrupts that use HSRR registers do not clear MSR[RI], but > NMI entry code is not recoverable early on due to both using HSPRG > for a scratch register. > > This bug means that a system reset or machine check can cause silent > data corruption (due to loss of r13 register) if it hits in a small > window when taking an HV interrupt. > > Fix this by marking NMIs non-recoverable if they land in HV interrupt > ranges.
Hum, I had a v2 that I didn't send properly with a small compile fix, but I've also just noticed this: > +void hv_nmi_check_nonrecoverable(struct pt_regs *regs) > +{ > +#ifdef CONFIG_POWERNV > + unsigned long kbase = (unsigned long)_stext; > + unsigned long nip = regs->nip; > + > + if (!(regs->msr & MSR_RI)) > + return; > + if (!(regs->msr & MSR_HV)) > + return; > + if (regs->msr & MSR_PR) > + return; > +again: > + if (nip >= 0x500 && nip < 0x600) > + goto nonrecoverable; > + if (nip >= 0x980 && nip < 0xa00) > + goto nonrecoverable; > + if (nip >= 0xe00 && nip < 0xec0) > + goto nonrecoverable; > + if (nip >= 0xf80 && nip < 0xfa0) > + goto nonrecoverable; > + /* Trampolines are not relocated. */ > + if (nip >= real_trampolines_start - kbase && > + nip < real_trampolines_end - kbase) > + goto nonrecoverable; > + if (nip >= virt_trampolines_start - kbase && > + nip < virt_trampolines_end - kbase) > + goto nonrecoverable; > + if (nip >= 0xc000000000000000ULL) { > + nip -= 0xc000000000000000ULL; > + goto again; Tried to be a bit too clever here. The 0xc... vectors also have a +0x4000 offset so this won't catch them properly. I'll respin. Thanks, Nick