Commit 6eac36bb authored by James Morse's avatar James Morse Committed by Borislav Petkov (AMD)
Browse files

x86/resctrl: Allocate the cleanest CLOSID by searching closid_num_dirty_rmid 



MPAM's PMG bits extend its PARTID space, meaning the same PMG value can be used
for different control groups.

This means once a CLOSID is allocated, all its monitoring ids may still be
dirty, and held in limbo.

Instead of allocating the first free CLOSID, on architectures where
CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID is enabled, search
closid_num_dirty_rmid[] to find the cleanest CLOSID.

The CLOSID found is returned to closid_alloc() for the free list
to be updated.

Signed-off-by: default avatarJames Morse <james.morse@arm.com>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: default avatarShaopeng Tan <tan.shaopeng@fujitsu.com>
Reviewed-by: default avatarReinette Chatre <reinette.chatre@intel.com>
Reviewed-by: default avatarBabu Moger <babu.moger@amd.com>
Tested-by: default avatarShaopeng Tan <tan.shaopeng@fujitsu.com>
Tested-by: default avatarPeter Newman <peternewman@google.com>
Tested-by: default avatarBabu Moger <babu.moger@amd.com>
Tested-by: Carl Worth <carl@os.amperecomputing.com> # arm64
Link: https://lore.kernel.org/r/20240213184438.16675-11-james.morse@arm.com


Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
parent 5d920b68

arch/x86/kernel/cpu/resctrl/internal.h

+2 −0
Original line number Diff line number Diff line
@@ -566,5 +566,7 @@ void rdt_domain_reconfigure_cdp(struct rdt_resource *r); 
void __init thread_throttle_mode_init(void);

void __init mbm_config_rftype_init(const char *config);

void rdt_staged_configs_clear(void);

bool closid_allocated(unsigned int closid);

int resctrl_find_cleanest_closid(void);



#endif /* _ASM_X86_RESCTRL_INTERNAL_H */

arch/x86/kernel/cpu/resctrl/monitor.c

+45 −0
Original line number Diff line number Diff line
@@ -386,6 +386,51 @@ static struct rmid_entry *resctrl_find_free_rmid(u32 closid) 
	return ERR_PTR(-ENOSPC);

}



/**

 * resctrl_find_cleanest_closid() - Find a CLOSID where all the associated

 *                                  RMID are clean, or the CLOSID that has

 *                                  the most clean RMID.

 *

 * MPAM's equivalent of RMID are per-CLOSID, meaning a freshly allocated CLOSID

 * may not be able to allocate clean RMID. To avoid this the allocator will

 * choose the CLOSID with the most clean RMID.

 *

 * When the CLOSID and RMID are independent numbers, the first free CLOSID will

 * be returned.

 */

int resctrl_find_cleanest_closid(void)

{

	u32 cleanest_closid = ~0;

	int i = 0;



	lockdep_assert_held(&rdtgroup_mutex);



	if (!IS_ENABLED(CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID))

		return -EIO;



	for (i = 0; i < closids_supported(); i++) {

		int num_dirty;



		if (closid_allocated(i))

			continue;



		num_dirty = closid_num_dirty_rmid[i];

		if (num_dirty == 0)

			return i;



		if (cleanest_closid == ~0)

			cleanest_closid = i;



		if (num_dirty < closid_num_dirty_rmid[cleanest_closid])

			cleanest_closid = i;

	}



	if (cleanest_closid == ~0)

		return -ENOSPC;



	return cleanest_closid;

}



/*

 * For MPAM the RMID value is not unique, and has to be considered with

 * the CLOSID. The (CLOSID, RMID) pair is allocated on all domains, which

arch/x86/kernel/cpu/resctrl/rdtgroup.c

+14 −5
Original line number Diff line number Diff line
@@ -137,13 +137,22 @@ static void closid_init(void) 


static int closid_alloc(void)

{

	u32 closid = ffs(closid_free_map);

	int cleanest_closid;

	u32 closid;



	lockdep_assert_held(&rdtgroup_mutex);



	if (IS_ENABLED(CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID)) {

		cleanest_closid = resctrl_find_cleanest_closid();

		if (cleanest_closid < 0)

			return cleanest_closid;

		closid = cleanest_closid;

	} else {

		closid = ffs(closid_free_map);

		if (closid == 0)

			return -ENOSPC;

		closid--;

	}

	__clear_bit(closid, &closid_free_map);



	return closid;
@@ -163,7 +172,7 @@ void closid_free(int closid) 
 * Return: true if @closid is currently associated with a resource group,

 * false if @closid is free

 */

static bool closid_allocated(unsigned int closid)

bool closid_allocated(unsigned int closid)

{

	lockdep_assert_held(&rdtgroup_mutex);