Re: [PATCH v7 07/17] ARM64 / ACPI: Disable ACPI if FADT revision is less than 5.1

[Lorenzo Pieralisi]

On Wed, Jan 14, 2015 at 03:04:55PM +0000, Hanjun Guo wrote:
> FADT Major.Minor version was introduced in ACPI 5.1, it is the same
> as ACPI version.
> 
> In ACPI 5.1, some major gaps are fixed for ARM, such as updates in
> MADT table for GIC and SMP init, without those updates, we can not
> get the MPIDR for SMP init, and GICv2/3 related init information, so
> we can't boot arm64 ACPI properly with table versions predating 5.1.
> 
> If firmware provides ACPI tables with ACPI version less than 5.1,
> OS will be messed up with those information and have no way to init

Nit: "that information"

or

"...OS has no way to retrieve the configuration data that is necessary
to init SMP boot protocol and the GIC properly, so.."

> smp and GIC, so disable ACPI if we get an FADT table with version
> less that 5.1.
> 

Patch should be reordered in the series and must be sequenced before
patch 5 for bisectability (that patch implements DT unflattening if ACPI
is disabled), or squashed with previous patches.

Lorenzo

> Tested-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@xxxxxxx>
> Tested-by: Yijing Wang <wangyijing@xxxxxxxxxx>
> Signed-off-by: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
> ---
>  arch/arm64/kernel/acpi.c | 31 ++++++++++++++++++++++++++++++-
>  1 file changed, 30 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
> index 39a1655..4177758 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/init.h>
>  #include <linux/acpi.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 arm boot flags, 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 +88,13 @@ 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))
> +		pr_err("Can't find FADT or error happened during parsing FADT\n");
>  }
>  
>  static int __init parse_acpi(char *arg)
> -- 
> 1.9.1
> 
> 
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