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Commit ff3e3fdc authored by Vitaly Kuznetsov's avatar Vitaly Kuznetsov Committed by Greg Kroah-Hartman
Browse files

KVM: selftests: Make sure kvm_create_max_vcpus test won't hit RLIMIT_NOFILE 



[ Upstream commit 908fa88e420f30dde6d80f092795a18ec72ca6d3 ]

With the elevated 'KVM_CAP_MAX_VCPUS' value kvm_create_max_vcpus test
may hit RLIMIT_NOFILE limits:

 # ./kvm_create_max_vcpus
 KVM_CAP_MAX_VCPU_ID: 4096
 KVM_CAP_MAX_VCPUS: 1024
 Testing creating 1024 vCPUs, with IDs 0...1023.
 /dev/kvm not available (errno: 24), skipping test

Adjust RLIMIT_NOFILE limits to make sure KVM_CAP_MAX_VCPUS fds can be
opened. Note, raising hard limit ('rlim_max') requires CAP_SYS_RESOURCE
capability which is generally not needed to run kvm selftests (but without
raising the limit the test is doomed to fail anyway).

Signed-off-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20211123135953.667434-1-vkuznets@redhat.com>
[Skip the test if the hard limit can be raised. - Paolo]
Reviewed-by: default avatarSean Christopherson <seanjc@google.com>
Tested-by: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent e8ef9403

tools/testing/selftests/kvm/kvm_create_max_vcpus.c

+30 −0
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ 
#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <sys/resource.h>



#include "test_util.h"
@@ -43,10 +44,39 @@ int main(int argc, char *argv[]) 
{

	int kvm_max_vcpu_id = kvm_check_cap(KVM_CAP_MAX_VCPU_ID);

	int kvm_max_vcpus = kvm_check_cap(KVM_CAP_MAX_VCPUS);

	/*

	 * Number of file descriptors reqired, KVM_CAP_MAX_VCPUS for vCPU fds +

	 * an arbitrary number for everything else.

	 */

	int nr_fds_wanted = kvm_max_vcpus + 100;

	struct rlimit rl;



	printf("KVM_CAP_MAX_VCPU_ID: %d\n", kvm_max_vcpu_id);

	printf("KVM_CAP_MAX_VCPUS: %d\n", kvm_max_vcpus);



	/*

	 * Check that we're allowed to open nr_fds_wanted file descriptors and

	 * try raising the limits if needed.

	 */

	TEST_ASSERT(!getrlimit(RLIMIT_NOFILE, &rl), "getrlimit() failed!");



	if (rl.rlim_cur < nr_fds_wanted) {

		rl.rlim_cur = nr_fds_wanted;

		if (rl.rlim_max < nr_fds_wanted) {

			int old_rlim_max = rl.rlim_max;

			rl.rlim_max = nr_fds_wanted;



			int r = setrlimit(RLIMIT_NOFILE, &rl);

			if (r < 0) {

				printf("RLIMIT_NOFILE hard limit is too low (%d, wanted %d)\n",

				       old_rlim_max, nr_fds_wanted);

				exit(KSFT_SKIP);

			}

		} else {

			TEST_ASSERT(!setrlimit(RLIMIT_NOFILE, &rl), "setrlimit() failed!");

		}

	}



	/*

	 * Upstream KVM prior to 4.8 does not support KVM_CAP_MAX_VCPU_ID.

	 * Userspace is supposed to use KVM_CAP_MAX_VCPUS as the maximum ID