Re: [PATCH v2 05/18] ARM64 / ACPI: Parse FADT table to get PSCI flags for PSCI init

From: Hanjun Guo
Date: Tue Aug 19 2014 - 06:41:40 EST

On 2014-8-19 2:32, Sudeep Holla wrote:
> On 04/08/14 16:28, Hanjun Guo wrote:
>> There are two flags: PSCI_COMPLIANT and PSCI_USE_HVC. When set,
>> the former signals to the OS that the hardware 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
>> bring up secondery CPUs, so disable ACPI if we get an FADT table
>> with version less that 5.1.
>>
[...]
>>
>> +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 version,
>> + * and there is a minor version of FADT which was introduced
>> + * by ACPI 5.1, we only deal with ACPI 5.1 or higher version
>> + * to get arm boot flags, or we will disable ACPI.
>> + */
>> + if (table->revision < 5 || fadt->minor_revision < 1) {
>
> &&

Catalin also pointed out this bug :), but && is not enough, for example,
this would not trigger of revision 4.1, although 4.1 is not exist, but
the code will still confusing people, so I updated the code as:

+ if (table->revision > 5 ||
+ (table->revision == 5 && fadt->minor_revision >= 1)) {
+ return 0;
+ } else {
+ pr_info("FADT revision is %d.%d, no PSCI support, should be 5.1
or higher\n",
+ table->revision, fadt->minor_revision);
+ disable_acpi();
+ return -EINVAL;
+ }

>
>> + pr_info("FADT version is %d.%d, no PSCI support, should be 5.1 or
>> higher\n",
>> + table->revision, fadt->minor_revision);
>> + disable_acpi();
>
> Instead of disabling ACPI at multiple places in the boot sequence, can't
> it be done once if acpi_boot_init failed ?
>
>> + return -EINVAL;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> /*
>> * acpi_boot_table_init() called from setup_arch(), always.
>> * 1. find RSDP and get its address, and then find XSDT
>> @@ -68,6 +90,21 @@ void __init acpi_boot_table_init(void)
>> }
>> }
>>
>> +int __init acpi_boot_init(void)
>> +{
>> + int err = 0;
>> +
>> + /* If acpi_disabled, bail out */
>> + if (acpi_disabled)
>> + return -ENODEV;
>> +
>> + err = acpi_table_parse(ACPI_SIG_FADT, acpi_parse_fadt);
>> + if (err)
>> + pr_err("Can't find FADT\n");
>> +
>> + return err;
>> +}
>> +
>> /*
>> * acpi_suspend_lowlevel() - save kernel state and suspend.
>> *
>> diff --git a/arch/arm64/kernel/psci.c b/arch/arm64/kernel/psci.c
>> index 9e9798f..2ad2084 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>
>> @@ -231,6 +232,33 @@ 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)
>> +{
>> + 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;
>> +}
>> +
>
> Nit: IMO may be you can move these refactoring as separate patch before
> ACPI related changes ?

I'm ok with it, will format another patch and place it in the
beginning of this patch set.

>
>> /*
>> * PSCI Function IDs for v0.2+ are well defined so use
>> * standard values.
>> @@ -264,29 +292,7 @@ static int 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);
>> @@ -333,6 +339,40 @@ out_put_node:
>> return err;
>> }
>>
>> +#ifdef CONFIG_ACPI
>> +static int get_set_conduit_method_acpi(void)
>> +{
>> + 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;
>> +
>> + return 0;
>> +}
>> +
>> +/* We use PSCI 0.2+ when ACPI is deployed */
>> +static int psci_0_2_init_acpi(void)
>
> May be this can be renamed psci_acpi_init and called from setup directly
> instead of calling from DT function with acpi_disabled check.

Also suggested by Catalin, will do it :)

>
>> +{
>> + if (!acpi_psci_present()) {
>> + pr_info("is not implemented in ACPI.\n");
>> + return -EOPNOTSUPP;
>> + }
>> +
>> + get_set_conduit_method_acpi();
>> +
>> + psci_0_2_set_functions();
>> +
>> + return 0;
>> +}
>> +#else
>> +static inline int psci_0_2_init_acpi(void)
>> +{
>> + return -ENODEV;
>> +}
>> +#endif
>> +
>> static const struct of_device_id psci_of_match[] __initconst = {
>> { .compatible = "arm,psci", .data = psci_0_1_init},
>> { .compatible = "arm,psci-0.2", .data = psci_0_2_init},
>> @@ -345,6 +385,9 @@ int __init psci_init(void)
>> const struct of_device_id *matched_np;
>> psci_initcall_t init_fn;
>>
>> + if (!acpi_disabled)
>> + return psci_0_2_init_acpi();
>> +
>
> As mentioned above you need not modify this.
>
>> np = of_find_matching_node_and_match(NULL, psci_of_match, &matched_np);
>>
>> if (!np)
>> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
>> index 85c6326..dfc4e4f3 100644
>> --- a/arch/arm64/kernel/setup.c
>> +++ b/arch/arm64/kernel/setup.c
>> @@ -395,6 +395,8 @@ void __init setup_arch(char **cmdline_p)
>> efi_idmap_init();
>>
>> cpu_logical_map(0) = read_cpuid_mpidr() & MPIDR_HWID_BITMASK;
>> + acpi_boot_init();
>> +
>
> Check for the return error here and disable ACPI once rather than at
> multiple places all over.

ok.

Thanks
Hanjun

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