hostcpu: Introduce virHostCPUGetSignature

The purpose of this function is to give a short description that would
be change when a host CPU is replaced with a different model. This is
currently implemented by reading /proc/cpuinfo.

It should be implemented for all architectures for which the QEMU driver
stores host CPU data in the capabilities cache. In other words for archs
that support host-model CPUs.

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>

src/libvirt_private.syms

@@ -2218,9 +2218,11 @@ virHostCPUGetMSR;
 virHostCPUGetOnline;
 virHostCPUGetOnlineBitmap;
 virHostCPUGetPresentBitmap;
+virHostCPUGetSignature;
 virHostCPUGetStats;
 virHostCPUGetThreadsPerSubcore;
 virHostCPUHasBitmap;
+virHostCPUReadSignature;
 virHostCPUStatsAssign;
 
 

src/util/virhostcpu.c

@@ -1416,3 +1416,40 @@ virHostCPUGetTscInfo(void)
 #endif /* HAVE_LINUX_KVM_H && defined(KVM_GET_MSRS) && \
           (defined(__i386__) || defined(__x86_64__)) && \
           (defined(__linux__) || defined(__FreeBSD__)) */
+
+int
+virHostCPUReadSignature(virArch arch G_GNUC_UNUSED,
+                        FILE *cpuinfo G_GNUC_UNUSED,
+                        char **signature G_GNUC_UNUSED)
+{
+    return 0;
+}
+
+#ifdef __linux__
+
+int
+virHostCPUGetSignature(char **signature)
+{
+    g_autoptr(FILE) cpuinfo = NULL;
+
+    *signature = NULL;
+
+    if (!(cpuinfo = fopen(CPUINFO_PATH, "r"))) {
+        virReportSystemError(errno, _("Failed to open cpuinfo file '%s'"),
+                             CPUINFO_PATH);
+        return -1;
+    }
+
+    return virHostCPUReadSignature(virArchFromHost(), cpuinfo, signature);
+}
+
+#else
+
+int
+virHostCPUGetSignature(char **signature)
+{
+    *signature = NULL;
+    return 0;
+}
+
+#endif /* __linux__ */

src/util/virhostcpu.h

@@ -79,3 +79,5 @@ int virHostCPUGetMSR(unsigned long index,
                      uint64_t *msr);
 
 virHostCPUTscInfoPtr virHostCPUGetTscInfo(void);
+
+int virHostCPUGetSignature(char **signature);

src/util/virhostcpupriv.h

@@ -42,3 +42,7 @@ int virHostCPUGetStatsLinux(FILE *procstat,
                             virNodeCPUStatsPtr params,
                             int *nparams);
 #endif
+
+int virHostCPUReadSignature(virArch arch,
+                            FILE *cpuinfo,
+                            char **signature);

tests/virhostcputest.c

@@ -1,6 +1,7 @@
 #include <config.h>
 
 #include <unistd.h>
+#include <fcntl.h>
 
 #include "testutils.h"
 #include "internal.h"
@@ -193,6 +194,38 @@ linuxTestHostCPU(const void *opaque)
     return result;
 }
 
+
+static int
+hostCPUSignature(const void *opaque)
+{
+    const struct linuxTestHostCPUData *data = opaque;
+    const char *arch = virArchToString(data->arch);
+    g_autofree char *cpuinfo = NULL;
+    g_autofree char *expected = NULL;
+    g_autofree char *signature = NULL;
+    g_autoptr(FILE) f = NULL;
+
+    cpuinfo = g_strdup_printf("%s/virhostcpudata/linux-%s-%s.cpuinfo",
+                              abs_srcdir, arch, data->testName);
+    expected = g_strdup_printf("%s/virhostcpudata/linux-%s-%s.signature",
+                               abs_srcdir, arch, data->testName);
+
+    if (!(f = fopen(cpuinfo, "r"))) {
+        virReportSystemError(errno,
+                             "Failed to open cpuinfo file '%s'", cpuinfo);
+        return -1;
+    }
+
+    if (virHostCPUReadSignature(data->arch, f, &signature) < 0)
+        return -1;
+
+    if (!signature && !virFileExists(expected))
+        return 0;
+
+    return virTestCompareToFile(signature, expected);
+}
+
+
 struct nodeCPUStatsData {
     const char *name;
     int ncpus;
@@ -268,10 +301,17 @@ mymain(void)
     if (virInitialize() < 0)
         return EXIT_FAILURE;
 
-    for (i = 0; i < G_N_ELEMENTS(nodeData); i++)
+    for (i = 0; i < G_N_ELEMENTS(nodeData); i++) {
+        g_autofree char *sigTest = NULL;
+
         if (virTestRun(nodeData[i].testName, linuxTestHostCPU, &nodeData[i]) != 0)
             ret = -1;
 
+        sigTest = g_strdup_printf("%s CPU signature", nodeData[i].testName);
+        if (virTestRun(sigTest, hostCPUSignature, &nodeData[i]) != 0)
+            ret = -1;
+    }
+
 # define DO_TEST_CPU_STATS(name, ncpus, shouldFail) \
     do { \
         static struct nodeCPUStatsData data = { name, ncpus, shouldFail}; \