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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.googlemail.com with ESMTPSA id g15sm6009639ejt.10.2021.12.13.06.22.17 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 13 Dec 2021 06:22:18 -0800 (PST) Sender: Paolo Bonzini Message-ID: <12be6cce-8e56-d69d-3338-3662b1fee12d@redhat.com> Date: Mon, 13 Dec 2021 15:22:17 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.2.0 Subject: Re: [PATCH MANUALSEL 5.4 2/2] KVM: selftests: Make sure kvm_create_max_vcpus test won't hit RLIMIT_NOFILE Content-Language: en-US To: Sasha Levin , linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Vitaly Kuznetsov , Sean Christopherson , shuah@kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org References: <20211213142028.352438-1-sashal@kernel.org> <20211213142028.352438-2-sashal@kernel.org> From: Paolo Bonzini In-Reply-To: <20211213142028.352438-2-sashal@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/13/21 15:20, Sasha Levin wrote: > From: Vitaly Kuznetsov > > [ 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 > Message-Id: <20211123135953.667434-1-vkuznets@redhat.com> > [Skip the test if the hard limit can be raised. - Paolo] > Reviewed-by: Sean Christopherson > Tested-by: Sean Christopherson > Signed-off-by: Paolo Bonzini > Signed-off-by: Sasha Levin > --- > .../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 231d79e57774e..cfe75536d8a55 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 > #include > #include > +#include > > #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 > Acked-by: Paolo Bonzini