Re: [PATCH 1/4] powerpc/64s: Fix HV NMI vs HV interrupt recoverability test

[Michael Ellerman <mpe@ellerman.id.au>]

Nicholas Piggin <npiggin@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