Commit e698e89b authored by Shivank Garg's avatar Shivank Garg Committed by Sean Christopherson
Browse files

KVM: selftests: Add helpers to probe for NUMA support, and multi-node systems 



Add NUMA helpers to probe for support/availability and to check if the
test is running on a multi-node system.  The APIs will be used to verify
guest_memfd NUMA support.

Signed-off-by: default avatarShivank Garg <shivankg@amd.com>
[sean: land helpers in numaif.h, add comments, tweak names]
Link: https://lore.kernel.org/r/20251016172853.52451-11-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent fe7baebb

tools/testing/selftests/kvm/include/numaif.h

+52 −0
Original line number Diff line number Diff line
@@ -4,6 +4,8 @@ 
#ifndef SELFTEST_KVM_NUMAIF_H

#define SELFTEST_KVM_NUMAIF_H



#include <dirent.h>



#include <linux/mempolicy.h>



#include "kvm_syscalls.h"
@@ -28,4 +30,54 @@ KVM_SYSCALL_DEFINE(mbind, 6, void *, addr, unsigned long, size, int, mode, 
		   const unsigned long *, nodemask, unsigned long, maxnode,

		   unsigned int, flags);



static inline int get_max_numa_node(void)

{

	struct dirent *de;

	int max_node = 0;

	DIR *d;



	/*

	 * Assume there's a single node if the kernel doesn't support NUMA,

	 * or if no nodes are found.

	 */

	d = opendir("/sys/devices/system/node");

	if (!d)

		return 0;



	while ((de = readdir(d)) != NULL) {

		int node_id;

		char *endptr;



		if (strncmp(de->d_name, "node", 4) != 0)

			continue;



		node_id = strtol(de->d_name + 4, &endptr, 10);

		if (*endptr != '\0')

			continue;



		if (node_id > max_node)

			max_node = node_id;

	}

	closedir(d);



	return max_node;

}



static bool is_numa_available(void)

{

	/*

	 * Probe for NUMA by doing a dummy get_mempolicy().  If the syscall

	 * fails with ENOSYS, then the kernel was built without NUMA support.

	 * if the syscall fails with EPERM, then the process/user lacks the

	 * necessary capabilities (CAP_SYS_NICE).

	 */

	return !get_mempolicy(NULL, NULL, 0, NULL, 0) ||

		(errno != ENOSYS && errno != EPERM);

}



static inline bool is_multi_numa_node_system(void)

{

	return is_numa_available() && get_max_numa_node() >= 1;

}



#endif /* SELFTEST_KVM_NUMAIF_H */