Subject: [PATCH v6 08/17] ARM64 / ACPI: Parse FADT table to get PSCI flags for PSCI init

From: [email-masked] (Lorenzo Pieralisi)
Date: Fri, 9 Jan 2015 19:04:00 +0000

On Sun, Jan 04, 2015 at 10:55:09AM +0000, Hanjun Guo wrote:
> There are two flags: PSCI_COMPLIANT and PSCI_USE_HVC. When set,
> the former signals to the OS that the firmware is PSCI compliant.
> The latter selects the appropriate conduit for PSCI calls by
> toggling between Hypervisor Calls (HVC) and Secure Monitor Calls
> (SMC).
> 
> FADT table contains such information, parse FADT to get the flags
> for PSCI init. Since ACPI 5.1 doesn't support self defined PSCI
> function IDs, which means that only PSCI 0.2+ is supported in ACPI.
> 
> At the same time, only ACPI 5.1 or higher verison supports PSCI,
> and FADT Major.Minor version was introduced in ACPI 5.1, so we
> will check the version and only parse FADT table with version >= 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
> smp and GIC, so disable ACPI if we get an FADT table with version
> less that 5.1.

I am a bit confused by this log. I understand the problem is that,
for versions predating 5.1, PSCI information is missing. So, I would
say:

"OS will not be able to boot properly owing to missing PSCI bindings
data in the ACPI tables".

Is that the message you want to get across ?

> Tested-by: Suravee Suthikulpanit <[email-masked]>
> Signed-off-by: Hanjun Guo <[email-masked]>
> Signed-off-by: Graeme Gregory <[email-masked]>
> Signed-off-by: Tomasz Nowicki <[email-masked]>
> ---
>  arch/arm64/include/asm/acpi.h | 14 ++++++++
>  arch/arm64/include/asm/psci.h |  3 +-
>  arch/arm64/kernel/acpi.c      | 31 ++++++++++++++++-
>  arch/arm64/kernel/psci.c      | 78 ++++++++++++++++++++++++++++++-------------
>  arch/arm64/kernel/setup.c     |  8 +++--
>  5 files changed, 105 insertions(+), 29 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h
> index 496c33b..221ff15 100644
> --- a/arch/arm64/include/asm/acpi.h
> +++ b/arch/arm64/include/asm/acpi.h
> @@ -19,6 +19,18 @@ extern int acpi_disabled;
>  extern int acpi_noirq;
>  extern int acpi_pci_disabled;
>  
> +/* 1 to indicate PSCI 0.2+ is implemented */
> +static inline bool acpi_psci_present(void)
> +{
> +	return acpi_gbl_FADT.arm_boot_flags & ACPI_FADT_PSCI_COMPLIANT;
> +}
> +
> +/* 1 to indicate HVC must be used instead of SMC as the PSCI conduit */
> +static inline bool acpi_psci_use_hvc(void)
> +{
> +	return acpi_gbl_FADT.arm_boot_flags & ACPI_FADT_PSCI_USE_HVC;
> +}
> +
>  static inline void disable_acpi(void)
>  {
>  	acpi_disabled = 1;
> @@ -49,6 +61,8 @@ static inline void arch_fix_phys_package_id(int num, u32 slot) { }
>  
>  #else
>  static inline void disable_acpi(void) { }
> +static inline bool acpi_psci_present(void) { return false; }
> +static inline bool acpi_psci_use_hvc(void) { return false; }
>  #endif /* CONFIG_ACPI */
>  
>  #endif /*_ASM_ACPI_H*/
> diff --git a/arch/arm64/include/asm/psci.h b/arch/arm64/include/asm/psci.h
> index e5312ea..2454bc5 100644
> --- a/arch/arm64/include/asm/psci.h
> +++ b/arch/arm64/include/asm/psci.h
> @@ -14,6 +14,7 @@
>  #ifndef __ASM_PSCI_H
>  #define __ASM_PSCI_H
>  
> -int psci_init(void);
> +int psci_dt_init(void);
> +int psci_acpi_init(void);

Is not there a better way to avoid this function dt/acpi duplication ?

>  
>  #endif /* __ASM_PSCI_H */
> diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
> index 39a1655..e713236 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();

I would rename this function, function is checking the FADT
revision, make that clear. I think that disable_acpi() should be
called on function return, if it fails.

To make the "acpi disabling" clearer, why not call this function in

psci_acpi_init()

something like:

int __init psci_acpi_init(void)
{

	if (acpi_table_parse(ACPI_SIG_FADT, acpi_parse_fadt)) {
		pr_err("Can't find FADT or error happened during parsing FADT\n");
		disable_acpi();
	}
	...
}

After all you disable ACPI because you can't retrieve PSCI information,
am I right ?

> +
> +	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 revisoin

s/revisoin/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");

As I said above this is a bit sneaky. It is not clear you are disabling
ACPI when the acpi_table_parse() call fails. Is it not better to move
the revision check in the PSCI ACPI init call ?

>  }
>  
>  static int __init parse_acpi(char *arg)
> diff --git a/arch/arm64/kernel/psci.c b/arch/arm64/kernel/psci.c
> index f1dbca7..dbb3945 100644
> --- a/arch/arm64/kernel/psci.c
> +++ b/arch/arm64/kernel/psci.c
> @@ -15,6 +15,7 @@
>  
>  #define pr_fmt(fmt) "psci: " fmt
>  
> +#include <linux/acpi.h>
>  #include <linux/init.h>
>  #include <linux/of.h>
>  #include <linux/smp.h>
> @@ -24,6 +25,7 @@
>  #include <linux/slab.h>
>  #include <uapi/linux/psci.h>
>  
> +#include <asm/acpi.h>
>  #include <asm/compiler.h>
>  #include <asm/cpu_ops.h>
>  #include <asm/errno.h>
> @@ -304,6 +306,33 @@ static void psci_sys_poweroff(void)
>  	invoke_psci_fn(PSCI_0_2_FN_SYSTEM_OFF, 0, 0, 0);
>  }
>  
> +static void psci_0_2_set_functions(void)

__init ?

> +{
> +	pr_info("Using standard PSCI v0.2 function IDs\n");
> +	psci_function_id[PSCI_FN_CPU_SUSPEND] = PSCI_0_2_FN64_CPU_SUSPEND;
> +	psci_ops.cpu_suspend = psci_cpu_suspend;
> +
> +	psci_function_id[PSCI_FN_CPU_OFF] = PSCI_0_2_FN_CPU_OFF;
> +	psci_ops.cpu_off = psci_cpu_off;
> +
> +	psci_function_id[PSCI_FN_CPU_ON] = PSCI_0_2_FN64_CPU_ON;
> +	psci_ops.cpu_on = psci_cpu_on;
> +
> +	psci_function_id[PSCI_FN_MIGRATE] = PSCI_0_2_FN64_MIGRATE;
> +	psci_ops.migrate = psci_migrate;
> +
> +	psci_function_id[PSCI_FN_AFFINITY_INFO] = PSCI_0_2_FN64_AFFINITY_INFO;
> +	psci_ops.affinity_info = psci_affinity_info;
> +
> +	psci_function_id[PSCI_FN_MIGRATE_INFO_TYPE] =
> +		PSCI_0_2_FN_MIGRATE_INFO_TYPE;
> +	psci_ops.migrate_info_type = psci_migrate_info_type;
> +
> +	arm_pm_restart = psci_sys_reset;
> +
> +	pm_power_off = psci_sys_poweroff;
> +}
> +
>  /*
>   * PSCI Function IDs for v0.2+ are well defined so use
>   * standard values.
> @@ -337,29 +366,7 @@ static int __init psci_0_2_init(struct device_node *np)
>  		}
>  	}
>  
> -	pr_info("Using standard PSCI v0.2 function IDs\n");
> -	psci_function_id[PSCI_FN_CPU_SUSPEND] = PSCI_0_2_FN64_CPU_SUSPEND;
> -	psci_ops.cpu_suspend = psci_cpu_suspend;
> -
> -	psci_function_id[PSCI_FN_CPU_OFF] = PSCI_0_2_FN_CPU_OFF;
> -	psci_ops.cpu_off = psci_cpu_off;
> -
> -	psci_function_id[PSCI_FN_CPU_ON] = PSCI_0_2_FN64_CPU_ON;
> -	psci_ops.cpu_on = psci_cpu_on;
> -
> -	psci_function_id[PSCI_FN_MIGRATE] = PSCI_0_2_FN64_MIGRATE;
> -	psci_ops.migrate = psci_migrate;
> -
> -	psci_function_id[PSCI_FN_AFFINITY_INFO] = PSCI_0_2_FN64_AFFINITY_INFO;
> -	psci_ops.affinity_info = psci_affinity_info;
> -
> -	psci_function_id[PSCI_FN_MIGRATE_INFO_TYPE] =
> -		PSCI_0_2_FN_MIGRATE_INFO_TYPE;
> -	psci_ops.migrate_info_type = psci_migrate_info_type;
> -
> -	arm_pm_restart = psci_sys_reset;
> -
> -	pm_power_off = psci_sys_poweroff;
> +	psci_0_2_set_functions();
>  
>  out_put_node:
>  	of_node_put(np);
> @@ -412,7 +419,7 @@ static const struct of_device_id psci_of_match[] __initconst = {
>  	{},
>  };
>  
> -int __init psci_init(void)
> +int __init psci_dt_init(void)
>  {
>  	struct device_node *np;
>  	const struct of_device_id *matched_np;
> @@ -427,6 +434,29 @@ int __init psci_init(void)
>  	return init_fn(np);
>  }
>  
> +/*
> + * We use PSCI 0.2+ when ACPI is deployed on ARM64 and it's
> + * explicitly clarified in SBBR
> + */
> +int __init psci_acpi_init(void)
> +{
> +	if (!acpi_psci_present()) {
> +		pr_info("is not implemented in ACPI.\n");
> +		return -EOPNOTSUPP;
> +	}
> +
> +	pr_info("probing for conduit method from ACPI.\n");
> +
> +	if (acpi_psci_use_hvc())
> +		invoke_psci_fn = __invoke_psci_fn_hvc;
> +	else
> +		invoke_psci_fn = __invoke_psci_fn_smc;
> +
> +	psci_0_2_set_functions();
> +
> +	return 0;

As I asked above, is not there a better way to have a common init
function and factor out the acpi/dt paths in it instead of adding
multiple calls in setup_arch() ?

Thanks,
Lorenzo

> +}
> +
>  #ifdef CONFIG_SMP
>  
>  static int __init cpu_psci_cpu_init(struct device_node *dn, unsigned int cpu)
> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
> index 2534de3..4322be2 100644
> --- a/arch/arm64/kernel/setup.c
> +++ b/arch/arm64/kernel/setup.c
> @@ -410,10 +410,12 @@ void __init setup_arch(char **cmdline_p)
>  
>  	efi_idmap_init();
>  
> -	if (acpi_disabled)
> +	if (acpi_disabled) {
>  		unflatten_device_tree();
> -
> -	psci_init();
> +		psci_dt_init();
> +	} else {
> +		psci_acpi_init();
> +	}
>  
>  	cpu_read_bootcpu_ops();
>  #ifdef CONFIG_SMP
> -- 
> 1.9.1
> 
>