From: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
[ 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: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
Message-Id: <20211123135953.667434-1-vkuznets@xxxxxxxxxx>
[Skip the test if the hard limit can be raised. - Paolo]
Reviewed-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Tested-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
tools/testing/selftests/kvm/kvm_create_max_vcpus.c | 30 +++++++++++++++++++++
1 file changed, 30 insertions(+)
--- a/tools/testing/selftests/kvm/kvm_create_max_vcpus.c
+++ b/tools/testing/selftests/kvm/kvm_create_max_vcpus.c
@@ -12,6 +12,7 @@
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
+#include <sys/resource.h>
#include "test_util.h"
@@ -43,11 +44,40 @@ 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
* in this case.
