Re: [PATCH v3 4/4] x86/CPU/AMD: Print the reason for the last reset

[Borislav Petkov]

On Thu, Apr 10, 2025 at 03:02:02PM -0500, Mario Limonciello wrote:
> +static __init int print_s5_reset_status_mmio(void)
> +{
> +	void __iomem *addr;
> +	unsigned long value;
> +	int bit = -1;
> +
> +	if (!cpu_feature_enabled(X86_FEATURE_ZEN))
> +		return 0;
> +
> +	addr = ioremap(FCH_PM_BASE + FCH_PM_S5_RESET_STATUS, sizeof(value));
> +	if (!addr)
> +		return 0;

newline.

> +	value = ioread32(addr);
> +	iounmap(addr);
> +
> +	do {
> +		bit = find_next_bit(&value, BITS_PER_LONG, bit + 1);
> +	} while (!s5_reset_reason_txt[bit]);

What's the idea here? The highest bit is the most fitting one?

So why don't you do fls() or so?

> +	pr_info("x86/amd: Previous system reset reason [0x%08lx]: %s\n",
> +		value, s5_reset_reason_txt[bit]);

What's guaranteeing that s5_reset_reason_txt[bit] is still set here?

I'd suggest you check it again and never trust the hw because we'll be fixing
a null ptr here at some point otherwise...

-- 
Regards/Gruss,
    Boris.

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