Use a minimum of 1 thread per core for CPU total calculation (#1756)

In some LXD containers running with VT-x hardware virtualization, it
appears that threads per core is 0, resulting in a total number of
CPUs of 0. Add a test case and handle some quirks with the `lscpu`
output.

Closes https://github.com/chef/ohai/issues/1755

Signed-off-by: Stan Hu <stanhu@gmail.com>

5 files changed, 169 insertions, 8 deletions

diff --git a/lib/ohai/plugins/cpu.rb b/lib/ohai/plugins/cpu.rb
index 1d37c39f..897f716b 100644
--- a/lib/ohai/plugins/cpu.rb
+++ b/lib/ohai/plugins/cpu.rb
@@ -193,7 +193,8 @@ Ohai.plugin(:CPU) do
           lscpu_real = lscpu_info[:sockets]
           lscpu_cores = lscpu_info[:sockets] * lscpu_info[:cores_per_socket]
         else
-          lscpu_total = lscpu_info[:sockets] * lscpu_info[:cores_per_socket] * lscpu_info[:threads_per_core]
+          threads_per_core = [lscpu_info[:threads_per_core], 1].max
+          lscpu_total = lscpu_info[:sockets] * lscpu_info[:cores_per_socket] * threads_per_core
           lscpu_real = lscpu_info[:sockets]
           lscpu_cores = lscpu_info[:sockets] * lscpu_info[:cores_per_socket]
         end
diff --git a/spec/data/plugins/cpuinfo-x86-guest-vtx.output b/spec/data/plugins/cpuinfo-x86-guest-vtx.output
new file mode 100644
index 00000000..645601f0
--- /dev/null
+++ b/spec/data/plugins/cpuinfo-x86-guest-vtx.output
@@ -0,0 +1,53 @@
+processor	: 0
+vendor_id	: GenuineIntel
+cpu family	: 6
+model		: 26
+model name	: Intel(R) Xeon(R) CPU           X5570  @ 2.93GHz
+stepping	: 5
+microcode	: 0x1d
+cpu MHz		: 1703.430
+cache size	: 8192 KB
+physical id	: 1
+siblings	: 8
+core id		: 2
+cpu cores	: 4
+apicid		: 21
+initial apicid	: 21
+fpu		: yes
+fpu_exception	: yes
+cpuid level	: 11
+wp		: yes
+flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm dca sse4_1 sse4_2 popcnt lahf_lm pti ssbd ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid dtherm ida flush_l1d
+bugs		: cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds swapgs itlb_multihit
+bogomips	: 5851.81
+clflush size	: 64
+cache_alignment	: 64
+address sizes	: 40 bits physical, 48 bits virtual
+power management:
+
+processor	: 1
+vendor_id	: GenuineIntel
+cpu family	: 6
+model		: 26
+model name	: Intel(R) Xeon(R) CPU           X5570  @ 2.93GHz
+stepping	: 5
+microcode	: 0x1d
+cpu MHz		: 1749.755
+cache size	: 8192 KB
+physical id	: 0
+siblings	: 8
+core id		: 2
+cpu cores	: 4
+apicid		: 5
+initial apicid	: 5
+fpu		: yes
+fpu_exception	: yes
+cpuid level	: 11
+wp		: yes
+flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm dca sse4_1 sse4_2 popcnt lahf_lm pti ssbd ibrs ibpb stibp tpr_shadow vnmi flexpriority ept vpid dtherm ida flush_l1d
+bugs		: cpu_meltdown spectre_v1 spectre_v2 spec_store_bypass l1tf mds swapgs itlb_multihit
+bogomips	: 5851.58
+clflush size	: 64
+cache_alignment	: 64
+address sizes	: 40 bits physical, 48 bits virtual
+power management:
diff --git a/spec/data/plugins/lscpu-x86-guest-vtx-cores.output b/spec/data/plugins/lscpu-x86-guest-vtx-cores.output
new file mode 100644
index 00000000..bbce1d8e
--- /dev/null
+++ b/spec/data/plugins/lscpu-x86-guest-vtx-cores.output
@@ -0,0 +1,6 @@
+# The following is the parsable format, which can be fed to other
+# programs. Each different item in every column has an unique ID
+# starting from zero.
+# CPU,Core,Socket
+12,4,0
+13,5,1
diff --git a/spec/data/plugins/lscpu-x86-guest-vtx.output b/spec/data/plugins/lscpu-x86-guest-vtx.output
new file mode 100644
index 00000000..01bb1137
--- /dev/null
+++ b/spec/data/plugins/lscpu-x86-guest-vtx.output
@@ -0,0 +1,26 @@
+Architecture:         x86_64
+CPU op-mode(s):       32-bit, 64-bit
+Byte Order:           Little Endian
+Address sizes:        40 bits physical, 48 bits virtual
+CPU(s):               16
+On-line CPU(s) list:  0,2,5,9
+Off-line CPU(s) list: 1,3,4,6-8,10-15
+Thread(s) per core:   0
+Core(s) per socket:   4
+Socket(s):            2
+NUMA node(s):         2
+Vendor ID:            GenuineIntel
+CPU family:           6
+Model:                26
+Model name:           Intel(R) Xeon(R) CPU           X5570  @ 2.93GHz
+Stepping:             5
+CPU MHz:              1596.085
+BogoMIPS:             5852.18
+Virtualization:       VT-x
+L1d cache:            32K
+L1i cache:            32K
+L2 cache:             256K
+L3 cache:             8192K
+NUMA node0 CPU(s):    0,2,4,6,8,10,12,14
+NUMA node1 CPU(s):    1,3,5,7,9,11,13,15
+Flags:                fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ht tm pbe syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm dca sse4_1 sse4_2 popcnt lahf_lm pti tpr_shadow vnmi flexpriority ept vpid dtherm ida
diff --git a/spec/unit/plugins/linux/cpu_spec.rb b/spec/unit/plugins/linux/cpu_spec.rb
index 92acdce6..c011a2bd 100644
--- a/spec/unit/plugins/linux/cpu_spec.rb
+++ b/spec/unit/plugins/linux/cpu_spec.rb
@@ -18,7 +18,7 @@
 
 require "spec_helper"
 
-shared_examples "Common cpu info" do |total_cpu, real_cpu, ls_cpu, architecture, cpu_opmodes, byte_order, cpus,
+shared_examples "Common cpu info" do |default_cpu, total_cpu, real_cpu, ls_cpu, architecture, cpu_opmodes, byte_order, cpus,
   cpus_online, threads_per_core, cores_per_socket, sockets, numa_nodes, vendor_id, model, model_name, bogomips,
   l1d_cache, l1i_cache, l2_cache, l3_cache, flags, numa_node_cpus|
   describe "cpu" do
@@ -27,9 +27,9 @@ shared_examples "Common cpu info" do |total_cpu, real_cpu, ls_cpu, architecture,
       expect(plugin[:cpu][:total]).to eq(total_cpu)
     end
 
-    it "has a cpu 0" do
+    it "has a default CPU" do
       plugin.run
-      expect(plugin[:cpu]).to have_key("0")
+      expect(plugin[:cpu]).to have_key(default_cpu)
     end
 
     if ls_cpu
@@ -84,10 +84,10 @@ shared_examples "Common cpu info" do |total_cpu, real_cpu, ls_cpu, architecture,
         expect(plugin[:cpu]["cores_per_socket"]).to eq(cores_per_socket)
       end
 
-      it "cpu 0 has cores to #{cores_per_socket}" do
+      it "default CPU has cores to #{cores_per_socket}" do
         plugin.run
-        expect(plugin[:cpu]["0"]).to have_key("cores")
-        expect(plugin[:cpu]["0"]["cores"]).to eq(cores_per_socket.to_s)
+        expect(plugin[:cpu][default_cpu]).to have_key("cores")
+        expect(plugin[:cpu][default_cpu]["cores"]).to eq(cores_per_socket.to_s)
       end
 
       # s390x shows this differently
@@ -385,6 +385,7 @@ describe Ohai::System, "General Linux cpu plugin" do
     let(:cpuinfo_contents) { File.read(File.join(SPEC_PLUGIN_PATH, "cpuinfo-no-cores.output")) }
 
     it_behaves_like "Common cpu info",
+      "0",  # default_cpu
       1,    # total_cpu
       1,    # real_cpu
       false # ls_cpu
@@ -478,6 +479,7 @@ describe Ohai::System, "General Linux cpu plugin" do
     numa_node_cpus = { "0" => [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23] }
 
     it_behaves_like "Common cpu info",
+      "0",                # default_cpu
       24,                 # total_cpu
       2,                  # real_cpu
       true,               # ls_cpu
@@ -553,6 +555,7 @@ describe Ohai::System, "General Linux cpu plugin" do
     numa_node_cpus = { "0" => [0, 1, 2, 3] }
 
     it_behaves_like "Common cpu info",
+      "0",                # default_cpu
       4,                  # total_cpu
       1,                  # real_cpu
       true,               # ls_cpu
@@ -615,6 +618,7 @@ describe Ohai::System, "General Linux cpu plugin" do
     numa_node_cpus = { "0" => [0, 1, 2, 3] }
 
     it_behaves_like "Common cpu info",
+      "0",                # default_cpu
       4,                  # total_cpu
       4,                  # real_cpu
       true,               # ls_cpu
@@ -663,6 +667,7 @@ describe Ohai::System, "General Linux cpu plugin" do
     numa_node_cpus = { "0" => [0] }
 
     it_behaves_like "Common cpu info",
+      "0",                # default_cpu
       1,                  # total_cpu
       1,                  # real_cpu
       true,               # ls_cpu
@@ -717,6 +722,7 @@ describe Ohai::System, "General Linux cpu plugin" do
     numa_node_cpus = { "0" => [0, 1, 2, 3] }
 
     it_behaves_like "Common cpu info",
+      "0",                # default_cpu
       4,                  # total_cpu
       1,                  # real_cpu
       true,               # ls_cpu
@@ -750,6 +756,65 @@ describe Ohai::System, "General Linux cpu plugin" do
       "Xen"               # hypervisor_vendor
   end
 
+  context "x86 guest on VT-x" do
+    let(:cpuinfo_contents) { File.read(File.join(SPEC_PLUGIN_PATH, "cpuinfo-x86-guest-vtx.output")) }
+    let(:lscpu) { File.read(File.join(SPEC_PLUGIN_PATH, "lscpu-x86-guest-vtx.output")) }
+    let(:lscpu_cores) { File.read(File.join(SPEC_PLUGIN_PATH, "lscpu-x86-guest-vtx-cores.output")) }
+
+    before do
+      allow(File).to receive(:open).with("/proc/cpuinfo").and_return(cpuinfo_contents)
+      allow(plugin).to receive(:shell_out).with("lscpu").and_return(mock_shell_out(0, lscpu, ""))
+      allow(plugin).to receive(:shell_out).with("lscpu -p=CPU,CORE,SOCKET").and_return(mock_shell_out(0, lscpu_cores, ""))
+    end
+
+    flags = %w{acpi aperfmperf apic arch_perfmon bts clflush cmov constant_tsc cpuid cx16 cx8 dca de ds_cpl dtes64 dtherm dts ept est flexpriority fpu fxsr ht ida lahf_lm lm mca mce mmx monitor msr mtrr nonstop_tsc nopl nx pae pat pbe pdcm pebs pge pni popcnt pse pse36 pti rdtscp rep_good sep sse sse2 sse4_1 sse4_2 ssse3 syscall tm tm2 tpr_shadow tsc vme vmx vnmi vpid xtopology xtpr}
+    numa_node_cpus = {
+      "0" => [0, 2, 4, 6, 8, 10, 12, 14],
+      "1" => [1, 3, 5, 7, 9, 11, 13, 15],
+    }
+
+    it_behaves_like "Common cpu info",
+      "12",               # default_cpu
+      8,                  # total_cpu
+      2,                  # real_cpu
+      true,               # ls_cpu
+      "x86_64",           # architecture
+      %w{32-bit 64-bit},  # cpu_opmodes
+      "little endian",    # byte_order
+      16,                 # cpus
+      4,                  # cpus_online
+      0,                  # threads_per_core
+      4,                  # cores_per_socket
+      2,                  # sockets
+      2,                  # numa_nodes
+      "GenuineIntel",     # vendor_id
+      "26",               # model
+      "Intel(R) Xeon(R) CPU           X5570  @ 2.93GHz", # model_name
+      "5852.18",          # bogomips
+      "32K",              # l1d_cache
+      "32K",              # l1i_cache
+      "256K",             # l2_cache
+      "8192K",            # l3_cache
+      flags,              # flags
+      numa_node_cpus      # numa_node_cpus
+
+    it "VT-x x86 processor info" do
+      plugin.run
+
+      expect(plugin[:cpu]).to have_key("family")
+      expect(plugin[:cpu]["family"]).to eq("6")
+
+      expect(plugin[:cpu]).to have_key("stepping")
+      expect(plugin[:cpu]["stepping"]).to eq("5")
+
+      expect(plugin[:cpu]).to have_key("mhz")
+      expect(plugin[:cpu]["mhz"]).to eq("1596.085")
+
+      expect(plugin[:cpu].keys).to include("12", "13")
+      expect(plugin[:cpu]["12"]).not_to have_key("cache_size")
+      expect(plugin[:cpu]["13"]).not_to have_key("cache_size")
+    end
+  end
 end
 
 describe Ohai::System, "S390 linux cpu plugin" do
@@ -764,6 +829,7 @@ describe Ohai::System, "S390 linux cpu plugin" do
   end
 
   it_behaves_like "Common cpu info",
+    "0",  # default_cpu
     4,    # total_cpu
     nil,  # real_cpu
     false # ls_cpu
@@ -809,6 +875,7 @@ describe Ohai::System, "S390 linux cpu plugin" do
     numa_node_cpus = { "0" => [0, 1, 2, 3] }
 
     it_behaves_like "Common cpu info",
+      "0",                # default_cpu
       4,                  # total_cpu
       1,                  # real_cpu
       true,               # ls_cpu
@@ -940,7 +1007,7 @@ describe Ohai::System, "arm64 linux cpu plugin" do
     allow(plugin).to receive(:shell_out).with("lscpu -p=CPU,CORE,SOCKET").and_return(mock_shell_out(1, "", ""))
   end
 
-  it_behaves_like "Common cpu info", 2, nil, false
+  it_behaves_like "Common cpu info", "0", 2, nil, false
 
   it "has a cpu 1" do
     plugin.run
@@ -971,6 +1038,7 @@ describe Ohai::System, "arm64 linux cpu plugin" do
     numa_node_cpus = { "0" => Range.new(0, 31).to_a }
 
     it_behaves_like "Common cpu info",
+      "0",                # default_cpu
       32,                 # total_cpu
       1,                  # real_cpu
       true,               # ls_cpu
@@ -1035,6 +1103,7 @@ describe Ohai::System, "arm64 linux cpu plugin" do
     numa_node_cpus = { "0" => Range.new(0, 1).to_a }
 
     it_behaves_like "Common cpu info",
+      "0",                # default_cpu
       2,                  # total_cpu
       1,                  # real_cpu
       true,               # ls_cpu
@@ -1078,6 +1147,7 @@ describe Ohai::System, "arm64 linux cpu plugin" do
     numa_node_cpus = { "0" => Range.new(0, 1).to_a }
 
     it_behaves_like "Common cpu info",
+      "0",                # default_cpu
       2,                  # total_cpu
       1,                  # real_cpu
       true,               # ls_cpu
@@ -1125,6 +1195,7 @@ describe Ohai::System, "ppc64le linux cpu plugin (POWER9)" do
   end
 
   it_behaves_like "Common cpu info",
+    "0",  # default_cpu
     2,    # total_cpu
     nil,  # real_cpu
     false # ls_cpu
@@ -1156,6 +1227,7 @@ describe Ohai::System, "ppc64le linux cpu plugin (POWER9)" do
       }
 
     it_behaves_like "Common cpu info",
+      "0",                # default_cpu
       32,                 # total_cpu
       2,                  # real_cpu
       true,               # ls_cpu
@@ -1234,6 +1306,7 @@ describe Ohai::System, "ppc64le linux cpu plugin (POWER9)" do
       }
 
     it_behaves_like "Common cpu info",
+      "0",                # default_cpu
       20,                 # total_cpu
       4,                  # real_cpu
       true,               # ls_cpu
@@ -1306,6 +1379,7 @@ describe Ohai::System, "ppc64le linux cpu plugin (POWER9)" do
     numa_node_cpus = { "0" => Range.new(0, 15).to_a }
 
     it_behaves_like "Common cpu info",
+      "0",                # default_cpu
       16,                 # total_cpu
       16,                 # real_cpu
       true,               # ls_cpu
@@ -1364,6 +1438,7 @@ describe Ohai::System, "ppc64le linux cpu plugin (POWER9)" do
     numa_node_cpus = { "0" => Range.new(0, 15).to_a }
 
     it_behaves_like "Common cpu info",
+      "0",                # default_cpu
       16,                 # total_cpu
       16,                 # real_cpu
       true,               # ls_cpu