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

From: Lorenzo Pieralisi
Date: Fri Jan 09 2015 - 14:04:17 EST

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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 <Suravee.Suthikulpanit@xxxxxxx>
> Signed-off-by: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
> Signed-off-by: Graeme Gregory <graeme.gregory@xxxxxxxxxx>
> Signed-off-by: Tomasz Nowicki <tomasz.nowicki@xxxxxxxxxx>
> ---
> 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
>
>
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Next message: Russell King - ARM Linux: "Re: ioremap vs remap_pfn_range, VMSPLIT, etc"
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