Hi Fenghua,

On 28/08/2025 02:29, Fenghua Yu wrote:

On 8/22/25 08:29, James Morse wrote:

quoted

An MSC is a container of resources, each identified by their RIS index.
Some RIS are described by firmware to provide their position in the system.
Others are discovered when the driver probes the hardware.

To configure a resource it needs to be found by its class, e.g. 'L2'.
There are two kinds of grouping, a class is a set of components, which
are visible to user-space as there are likely to be multiple instances
of the L2 cache. (e.g. one per cluster or package)

struct mpam_components are a set of struct mpam_vmsc. A vMSC groups the
RIS in an MSC that control the same logical piece of hardware. (e.g. L2).
This is to allow hardware implementations where two controls are presented
as different RIS. Re-combining these RIS allows their feature bits to
be or-ed. This structure is not visible outside mpam_devices.c

struct mpam_vmsc are then a set of struct mpam_msc_ris, which are not
visible as each L2 cache may be composed of individual slices which need
to be configured the same as the hardware is not able to distribute the
configuration.

Add support for creating and destroying these structures.

A gfp is passed as the structures may need creating when a new RIS entry
is discovered when probing the MSC.

quoted

diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
index 71a1fb1a9c75..5baf2a8786fb 100644
--- a/drivers/resctrl/mpam_devices.c
+++ b/drivers/resctrl/mpam_devices.c

[SNIP]

quoted

+static struct mpam_vmsc *
+mpam_vmsc_alloc(struct mpam_component *comp, struct mpam_msc *msc, gfp_t gfp)
+{
+    struct mpam_vmsc *vmsc;
+
+    lockdep_assert_held(&mpam_list_lock);
+
+    vmsc = kzalloc(sizeof(*vmsc), gfp);
+    if (!comp)

s/if (!cmp)/if (!vmsc)/

quoted

+        return ERR_PTR(-ENOMEM);

Yup, that's a copy-and-paste typo. Fixed,


Thanks,

James