Re: [PATCH v8 09/21] ARM64 / ACPI: Disable ACPI if FADT revision is less than 5.1

[Hanjun Guo]

On 2015å02æ04æ 01:20, Catalin Marinas wrote:
> On Mon, Feb 02, 2015 at 12:45:37PM +0000, Hanjun Guo wrote:
> > diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
> > index afe10b4..b9f64ec 100644
> > --- a/arch/arm64/kernel/acpi.c
> > +++ b/arch/arm64/kernel/acpi.c
> > @@ -13,6 +13,8 @@
> >    *  published by the Free Software Foundation.
> >    */
> >
> > +#define pr_fmt(fmt) "ACPI: " fmt
> > +
> >   #include <linux/acpi.h>
> >   #include <linux/bootmem.h>
> >   #include <linux/cpumask.h>
> > @@ -49,10 +51,32 @@ void __init __acpi_unmap_table(char *map, unsigned long size)
> >   	early_memunmap(map, size);
> >   }
> >
> > +static int __init acpi_parse_fadt(struct acpi_table_header *table)
> > +{
> > +	struct acpi_table_fadt *fadt = (struct acpi_table_fadt *)table;
> > +
> > +	/*
> > +	 * Revision in table header is the FADT Major revision, and there
> > +	 * is a minor revision of FADT which was introduced by ACPI 5.1,
> > +	 * we only deal with ACPI 5.1 or newer revision to get GIC and SMP
> > +	 * boot protocol configuration data, or we will disable ACPI.
> > +	 */
> > +	if (table->revision > 5 ||
> > +	    (table->revision == 5 && fadt->minor_revision >= 1))
> > +		return 0;
> > +
> > +	pr_warn("Unsupported FADT revision %d.%d, should be 5.1+, will disable ACPI\n",
> > +		table->revision, fadt->minor_revision);
> > +	disable_acpi();
> > +
> > +	return -EINVAL;
> > +}
> > +
> >   /*
> >    * acpi_boot_table_init() called from setup_arch(), always.
> >    *	1. find RSDP and get its address, and then find XSDT
> >    *	2. extract all tables and checksums them all
> > + *	3. check ACPI FADT revision
> >    *
> >    * We can parse ACPI boot-time tables such as MADT after
> >    * this function is called.
> > @@ -64,8 +88,16 @@ void __init acpi_boot_table_init(void)
> >   		return;
> >
> >   	/* Initialize the ACPI boot-time table parser. */
> > -	if (acpi_table_init())
> > +	if (acpi_table_init()) {
> > +		disable_acpi();
> > +		return;
> > +	}
> > +
> > +	if (acpi_table_parse(ACPI_SIG_FADT, acpi_parse_fadt)) {
> > +		/* disable ACPI if no FADT is found */
> >   		disable_acpi();
> > +		pr_err("Can't find FADT\n");
> > +	}
> >   }
>
> It looks fine to call disable_acpi() here but a bit weird to call it
> again in acpi_parse_fadt(). I guess that's because acpi_table_parse()
> ignores the return value of the handler() call. I think it's better to
> fix the core code (can be an additional patch on top of this series).

I checked all the code calling acpi_table_parse() and I found that it
will be no functional change if we return the value of handler(), but
I need Rafael's confirm on it.

Thanks
Hanjun
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