Re: [PATCH] platform/x86: ISST: PUNIT device mapping with Sub-NUMA clustering

Hans de Goede
2022-06-28T20:20:29Z

Hi,

On 6/27/22 23:50, Srinivas Pandruvada wrote:
> On a multiple package system using Sub-NUMA clustering, there is an issue
> in mapping Linux CPU number to PUNIT PCI device when manufacturer decided
> to reuse the PCI bus number across packages. Bus number can be reused as
> long as they are in different domain or segment. In this case some CPU
> will fail to find a PCI device to issue SST requests.
>
> When bus numbers are reused across CPU packages, we are using proximity
> information by matching CPU numa node id to PUNIT PCI device numa node
> id. But on a package there can be only one PUNIT PCI device, but multiple
> numa nodes (one for each sub cluster). So, the numa node ID of the PUNIT
> PCI device can only match with one numa node id of CPUs in a sub cluster
> in the package.
>
> Since there can be only one PUNIT PCI device per package, if we match
> with numa node id of any sub cluster in that package, we can use that
> mapping for any CPU in that package. So, store the match information
> in a per package data structure and return the information when there
> is no match.
>
> Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
> ---
> .../intel/speed_select_if/isst_if_common.c | 22 +++++++++++++++++++
> 1 file changed, 22 insertions(+)
>
> diff --git a/drivers/platform/x86/intel/speed_select_if/isst_if_common.c b/drivers/platform/x86/intel/speed_select_if/isst_if_common.c
> index e8424e70d81d..f3cd1be3283a 100644
> --- a/drivers/platform/x86/intel/speed_select_if/isst_if_common.c
> +++ b/drivers/platform/x86/intel/speed_select_if/isst_if_common.c
> @@ -286,11 +286,18 @@ struct isst_if_cpu_info {
> int numa_node;
> };
>
> +struct isst_if_pkg_info {
> + struct pci_dev *pci_dev[2];

This and (continued below) ...

> +};
> +
> static struct isst_if_cpu_info *isst_cpu_info;
> +static struct isst_if_pkg_info *isst_pkg_info;
> +
> #define ISST_MAX_PCI_DOMAINS 8
>
> static struct pci_dev *_isst_if_get_pci_dev(int cpu, int bus_no, int dev, int fn)
> {
> + int pkg_id = topology_physical_package_id(cpu);
> struct pci_dev *matched_pci_dev = NULL;
> struct pci_dev *pci_dev = NULL;
> int no_matches = 0;
> @@ -324,6 +331,8 @@ static struct pci_dev *_isst_if_get_pci_dev(int cpu, int bus_no, int dev, int fn
> }
>
> if (node == isst_cpu_info[cpu].numa_node) {
> + isst_pkg_info[pkg_id].pci_dev[bus_no] = _pci_dev;
> +

This and ...

> pci_dev = _pci_dev;
> break;
> }
> @@ -342,6 +351,9 @@ static struct pci_dev *_isst_if_get_pci_dev(int cpu, int bus_no, int dev, int fn
> if (!pci_dev && no_matches == 1)
> pci_dev = matched_pci_dev;
>
> + if (!pci_dev)
> + pci_dev = isst_pkg_info[pkg_id].pci_dev[bus_no];
> +

This assumes that bus_no is never > 1, is this assumption enforced somewhere?

Also maybe make the 2 in:

> +struct isst_if_pkg_info {
> + struct pci_dev *pci_dev[2];

a #define ?

Regards,

Hans

> return pci_dev;
> }
>
> @@ -417,10 +429,19 @@ static int isst_if_cpu_info_init(void)
> if (!isst_cpu_info)
> return -ENOMEM;
>
> + isst_pkg_info = kcalloc(topology_max_packages(),
> + sizeof(*isst_pkg_info),
> + GFP_KERNEL);
> + if (!isst_pkg_info) {
> + kfree(isst_cpu_info);
> + return -ENOMEM;
> + }
> +
> ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
> "platform/x86/isst-if:online",
> isst_if_cpu_online, NULL);
> if (ret < 0) {
> + kfree(isst_pkg_info);
> kfree(isst_cpu_info);
> return ret;
> }
> @@ -433,6 +454,7 @@ static int isst_if_cpu_info_init(void)
> static void isst_if_cpu_info_exit(void)
> {
> cpuhp_remove_state(isst_if_online_id);
> + kfree(isst_pkg_info);
> kfree(isst_cpu_info);
> };
>