Nicholas Piggin <npig...@gmail.com> writes:
> 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.

I'm seeing the same build error as the kbuild robot too.

cheers

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