Re: [PATCH v2 06/13] platform/x86: hfi: parse CPU core ranking data from shared memory

[Ilpo Järvinen]

On Thu, 10 Oct 2024, Mario Limonciello wrote:

> From: Perry Yuan <Perry.Yuan@xxxxxxx>
> 
> When `amd_hfi` driver is loaded, it will use PCCT subspace type 4 table
> to retrieve the shared memory address which contains the CPU core ranking
> table. This table includes a header that specifies the number of ranking
> data entries to be parsed and rank each CPU core with the Performance and
> Energy Efficiency capability as implemented by the CPU power management
> firmware.
> 
> Once the table has been parsed, each CPU is assigned a ranking score
> within its class. Subsequently, when the scheduler selects cores, it
> chooses from the ranking list based on the assigned scores in each class,
> thereby ensuring the optimal selection of CPU cores according to their
> predefined classifications and priorities.
> 
> Signed-off-by: Perry Yuan <Perry.Yuan@xxxxxxx>
> Co-developed-by: Mario Limonciello <mario.limonciello@xxxxxxx>
> Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
> ---
> v2:
>  * Rework amd_hfi_fill_metatadata to directly use structure instead of
>    pointer math.
> ---
>  drivers/platform/x86/amd/hfi/hfi.c | 215 ++++++++++++++++++++++++++++-
>  1 file changed, 212 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/platform/x86/amd/hfi/hfi.c b/drivers/platform/x86/amd/hfi/hfi.c
> index da2e667107e8..10651399cf75 100644
> --- a/drivers/platform/x86/amd/hfi/hfi.c
> +++ b/drivers/platform/x86/amd/hfi/hfi.c
> @@ -18,22 +18,78 @@
>  #include <linux/io.h>
>  #include <linux/kernel.h>
>  #include <linux/module.h>
> +#include <linux/mailbox_client.h>
>  #include <linux/mutex.h>
> +#include <linux/percpu-defs.h>
>  #include <linux/platform_device.h>
>  #include <linux/printk.h>
>  #include <linux/smp.h>
>  #include <linux/string.h>
> +#include <linux/topology.h>
> +#include <linux/workqueue.h>
> +
> +#include <asm/cpu_device_id.h>
> +
> +#include <acpi/pcc.h>
> +#include <acpi/cppc_acpi.h>
>  
>  #define AMD_HFI_DRIVER		"amd_hfi"
> +#define AMD_HFI_MAILBOX_COUNT	1
> +#define AMD_HETERO_RANKING_TABLE_VER	2
> +
>  #define AMD_HETERO_CPUID_27	0x80000027
> +
>  static struct platform_device *device;
>  
> +/**
> + * struct amd_shmem_info - Shared memory table for AMD HFI
> + *
> + * @signature:	The PCC signature. The signature of a subspace is computed by
> + *		a bitwise of the value 0x50434300 with the subspace ID.
> + * @flags:	Notify on completion
> + * @length:	Length of payload being transmitted including command field
> + * @command:	Command being sent over the subspace
> + * @version_number:		Version number of the table
> + * @n_logical_processors:	Number of logical processors
> + * @n_capabilities:		Number of ranking dimensions (performance, efficiency, etc)
> + * @table_update_context:	Command being sent over the subspace
> + * @n_bitmaps:			Number of 32-bit bitmaps to enumerate all the APIC IDs
> + *				This is based on the maximum APIC ID enumerated in the system
> + * @reserved:			24 bit spare
> + * @table_data:			Bit Map(s) of enabled logical processors
> + *				Followed by the ranking data for each logical processor
> + */
> +struct amd_shmem_info {
> +	struct acpi_pcct_ext_pcc_shared_memory header;
> +	u32	version_number		:8,
> +		n_logical_processors	:8,
> +		n_capabilities		:8,
> +		table_update_context	:8;
> +	u32	n_bitmaps		:8,
> +		reserved		:24;
> +	u32	table_data[];
> +} __packed;
> +
>  struct amd_hfi_data {
>  	const char	*name;
>  	struct device	*dev;
>  	struct mutex	lock;
> +
> +	/* PCCT table related*/
> +	struct pcc_mbox_chan	*pcc_chan;
> +	void __iomem		*pcc_comm_addr;
> +	struct acpi_subtable_header	*pcct_entry;
> +	struct amd_shmem_info	*shmem;
>  };
>  
> +/**
> + * struct amd_hfi_classes - HFI class capabilities per CPU
> + * @perf:	Performance capability
> + * @eff:	Power efficiency capability
> + *
> + * Capabilities of a logical processor in the ranking table. These capabilities
> + * are unitless and specific to each HFI class.
> + */
>  struct amd_hfi_classes {
>  	u32	perf;
>  	u32	eff;
> @@ -42,23 +98,105 @@ struct amd_hfi_classes {
>  /**
>   * struct amd_hfi_cpuinfo - HFI workload class info per CPU
>   * @cpu:		cpu index
> + * @apic_id:		apic id of the current cpu
>   * @cpus:		mask of cpus associated with amd_hfi_cpuinfo
>   * @class_index:	workload class ID index
>   * @nr_class:		max number of workload class supported
> + * @ipcc_scores:	ipcc scores for each class
>   * @amd_hfi_classes:	current cpu workload class ranking data
>   *
>   * Parameters of a logical processor linked with hardware feedback class
>   */
>  struct amd_hfi_cpuinfo {
>  	int		cpu;
> +	u32		apic_id;
>  	cpumask_var_t	cpus;
>  	s16		class_index;
>  	u8		nr_class;
> +	int		*ipcc_scores;
>  	struct amd_hfi_classes	*amd_hfi_classes;
>  };
>  
>  static DEFINE_PER_CPU(struct amd_hfi_cpuinfo, amd_hfi_cpuinfo) = {.class_index = -1};
>  
> +static int find_cpu_index_by_apicid(unsigned int target_apicid)
> +{
> +	int cpu_index;
> +
> +	for_each_possible_cpu(cpu_index) {
> +		struct cpuinfo_x86 *info = &cpu_data(cpu_index);
> +
> +		if (info->topo.apicid == target_apicid) {
> +			pr_debug("match APIC id %d for CPU index: %d",

Missing \n

> +				 info->topo.apicid, cpu_index);
> +			return cpu_index;
> +		}
> +	}
> +
> +	return -ENODEV;
> +}
> +
> +static int amd_hfi_fill_metadata(struct amd_hfi_data *amd_hfi_data)
> +{
> +	struct acpi_pcct_ext_pcc_slave *pcct_ext =
> +		(struct acpi_pcct_ext_pcc_slave *)amd_hfi_data->pcct_entry;
> +	void __iomem *pcc_comm_addr;
> +
> +	pcc_comm_addr = acpi_os_ioremap(amd_hfi_data->pcc_chan->shmem_base_addr,
> +					amd_hfi_data->pcc_chan->shmem_size);
> +	if (!pcc_comm_addr) {
> +		pr_err("failed to ioremap PCC common region mem\n");
> +		return -ENOMEM;
> +	}
> +
> +	memcpy_fromio(amd_hfi_data->shmem, pcc_comm_addr, pcct_ext->length);
> +	iounmap(pcc_comm_addr);
> +
> +	if (amd_hfi_data->shmem->header.signature != PCC_SIGNATURE) {
> +		pr_err("Invalid signature in shared memory\n");
> +		return -EINVAL;
> +	}
> +	if (amd_hfi_data->shmem->version_number != AMD_HETERO_RANKING_TABLE_VER) {
> +		pr_err("Invalid veresion %d\n", amd_hfi_data->shmem->version_number);

version

> +		return -EINVAL;
> +	}
> +
> +	for (u32 i = 0; i < amd_hfi_data->shmem->n_bitmaps; i++) {
> +		u32 bitmap = amd_hfi_data->shmem->table_data[i];
> +
> +		for (u32 j = 0; j < BITS_PER_TYPE(u32); j++) {

Are these u32 really the types you want to use for the loop vars, why?

> +			struct amd_hfi_cpuinfo *info;
> +			int apic_id = i * BITS_PER_TYPE(u32) + j;
> +			int cpu_index;
> +
> +			if (!(bitmap & BIT(j)))
> +				continue;
> +
> +			cpu_index = find_cpu_index_by_apicid(apic_id);
> +			if (cpu_index < 0) {
> +				pr_warn("APIC ID %d not found\n", apic_id);
> +				continue;
> +			}
> +
> +			info = per_cpu_ptr(&amd_hfi_cpuinfo, cpu_index);
> +			info->apic_id = apic_id;
> +
> +			/* Fill the ranking data for each logical processor */
> +			info = per_cpu_ptr(&amd_hfi_cpuinfo, cpu_index);
> +			for (int k = 0; k < info->nr_class; k++) {

unsigned int

> +				u32 *table = amd_hfi_data->shmem->table_data +
> +					     amd_hfi_data->shmem->n_bitmaps +
> +					     i * info->nr_class;
> +
> +				info->amd_hfi_classes[k].eff = table[apic_id + 2 * k];
> +				info->amd_hfi_classes[k].perf = table[apic_id + 2 * k + 1];
> +			}
> +		}
> +	}
> +
> +	return 0;
> +}
> +
>  static int amd_hfi_alloc_class_data(struct platform_device *pdev)
>  {
>  	struct amd_hfi_cpuinfo *hfi_cpuinfo;
> @@ -68,8 +206,7 @@ static int amd_hfi_alloc_class_data(struct platform_device *pdev)
>  
>  	nr_class_id = cpuid_eax(AMD_HETERO_CPUID_27);
>  	if (nr_class_id < 0 || nr_class_id > 255) {
> -		dev_warn(dev, "failed to get supported class number from CPUID %d\n",
> -				AMD_HETERO_CPUID_27);
> +		dev_warn(dev, "failed to get number of supported classes\n");

This message was added in the previous patch and now immediately changed.

>  		return -EINVAL;
>  	}
>  
> @@ -79,7 +216,10 @@ static int amd_hfi_alloc_class_data(struct platform_device *pdev)
>  				sizeof(struct amd_hfi_classes), GFP_KERNEL);
>  		if (!hfi_cpuinfo->amd_hfi_classes)
>  			return -ENOMEM;
> -
> +		hfi_cpuinfo->ipcc_scores = devm_kcalloc(dev, nr_class_id,
> +							sizeof(int), GFP_KERNEL);
> +		if (!hfi_cpuinfo->ipcc_scores)
> +			return -ENOMEM;
>  		hfi_cpuinfo->nr_class = nr_class_id;
>  	}
>  
> @@ -93,6 +233,70 @@ static void amd_hfi_remove(struct platform_device *pdev)
>  	mutex_destroy(&dev->lock);
>  }
>  
> +static int amd_hfi_metadata_parser(struct platform_device *pdev,
> +				   struct amd_hfi_data *amd_hfi_data)
> +{
> +	struct acpi_pcct_ext_pcc_slave *pcct_ext;
> +	struct acpi_subtable_header *pcct_entry;
> +	struct mbox_chan *pcc_mbox_channels;
> +	struct acpi_table_header *pcct_tbl;
> +	struct pcc_mbox_chan *pcc_chan;
> +	acpi_status status;
> +	int ret;
> +
> +	pcc_mbox_channels = devm_kcalloc(&pdev->dev, AMD_HFI_MAILBOX_COUNT,
> +					 sizeof(*pcc_mbox_channels), GFP_KERNEL);
> +	if (!pcc_mbox_channels) {
> +		ret = -ENOMEM;
> +		goto out;

Please return directly if there is nothing to rollback.

> +	}
> +
> +	pcc_chan = devm_kcalloc(&pdev->dev, AMD_HFI_MAILBOX_COUNT,
> +				sizeof(*pcc_chan), GFP_KERNEL);
> +	if (!pcc_chan) {
> +		ret = -ENOMEM;
> +		goto out;

Ditto.

> +	}
> +
> +	status = acpi_get_table(ACPI_SIG_PCCT, 0, &pcct_tbl);
> +	if (ACPI_FAILURE(status) || !pcct_tbl) {
> +		ret = -ENODEV;
> +		goto out;

Ditto.

> +	}
> +
> +	/* get pointer to the first PCC subspace entry */
> +	pcct_entry = (struct acpi_subtable_header *) (
> +			(unsigned long)pcct_tbl + sizeof(struct acpi_table_pcct));
> +
> +	pcc_chan->mchan = &pcc_mbox_channels[0];
> +
> +	amd_hfi_data->pcc_chan = pcc_chan;
> +	amd_hfi_data->pcct_entry = pcct_entry;
> +	pcct_ext = (struct acpi_pcct_ext_pcc_slave *)pcct_entry;
> +
> +	if (pcct_ext->length <= 0) {
> +		ret = -EINVAL;
> +		goto out;

Ditto.

> +	}
> +
> +	amd_hfi_data->shmem = devm_kmalloc(amd_hfi_data->dev, pcct_ext->length, GFP_KERNEL);

Why kmalloc ?

> +	if (!amd_hfi_data->shmem) {
> +		ret = -ENOMEM;
> +		goto out;

Return directly.

> +	}
> +
> +	pcc_chan->shmem_base_addr = pcct_ext->base_address;
> +	pcc_chan->shmem_size = pcct_ext->length;
> +
> +	/* parse the shared memory info from the pcct table */
> +	ret = amd_hfi_fill_metadata(amd_hfi_data);
> +
> +	acpi_put_table(pcct_tbl);
> +
> +out:
> +	return ret;
> +}
> +
>  static const struct acpi_device_id amd_hfi_platform_match[] = {
>  	{ "AMDI0104", 0},
>  	{ }
> @@ -121,6 +325,11 @@ static int amd_hfi_probe(struct platform_device *pdev)
>  	if (ret)
>  		goto out;

This should do return ret; directly, not jump to out label which does 
nothing but return.

>  
> +	/* parse PCCT table */
> +	ret = amd_hfi_metadata_parser(pdev, amd_hfi_data);
> +	if (ret)
> +		goto out;
> +
>  out:
>  	return ret;

Might again be there for churn avoidance, otherwise, please consider:

	return amd_hfi_metadata_parser(pdev, amd_hfi_data);

That goto out should again just return ret directly.

>  }
> 

-- 
 i.