On 12/13/21 15:20, Sasha Levin wrote:

From: Vitaly Kuznetsov vkuznets@redhat.com

[ 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@redhat.com Message-Id: 20211123135953.667434-1-vkuznets@redhat.com [Skip the test if the hard limit can be raised. - Paolo] Reviewed-by: Sean Christopherson seanjc@google.com Tested-by: Sean Christopherson seanjc@google.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org

---

.../selftests/kvm/kvm_create_max_vcpus.c | 30 +++++++++++++++++++ 1 file changed, 30 insertions(+)

diff --git a/tools/testing/selftests/kvm/kvm_create_max_vcpus.c b/tools/testing/selftests/kvm/kvm_create_max_vcpus.c index 0299cd81b8ba2..aa3795cd7bd3d 100644 --- 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" @@ -40,10 +41,39 @@ 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;

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

Acked-by: Paolo Bonzini pbonzini@redhat.com