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

Lorenzo Pieralisi
2015-01-16T14:33:47Z

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@amd.com>
> Tested-by: Yijing Wang <wangyijing@huawei.com>
> Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
> ---
> 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
>
>