host-validate: Improve CPU flags processing

Instead of relying on substring search, tokenize the input
and process each CPU flag separately. This ensures CPU flag
detection will continue to work correctly even if we start
looking for CPU flags whose name might appear as part of
other CPU flags' names.

The result of processing is stored in a virBitmap, which
means we don't have to parse /proc/cpuinfo in its entirety
for each single CPU flag we want to check.

Moreover, use of the newly-introduced virHostValidateCPUFlag
enumeration ensures we don't go looking for random CPU flags
which might actually be simple typos.

tools/virt-host-validate-common.c

@@ -31,7 +31,6 @@
 #endif /* HAVE_MNTENT_H */
 #include <sys/stat.h>
 
-#include "virutil.h"
 #include "viralloc.h"
 #include "virfile.h"
 #include "virt-host-validate-common.h"
@@ -39,6 +38,10 @@
 
 #define VIR_FROM_THIS VIR_FROM_NONE
 
+VIR_ENUM_IMPL(virHostValidateCPUFlag, VIR_HOST_VALIDATE_CPU_FLAG_LAST,
+              "vmx",
+              "svm");
+
 static bool quiet;
 
 void virHostMsgSetQuiet(bool quietFlag)
@@ -188,29 +191,64 @@ int virHostValidateNamespace(const char *hvname,
 }
 
 
-bool virHostValidateHasCPUFlag(const char *name)
+virBitmapPtr virHostValidateGetCPUFlags(void)
 {
-    FILE *fp = fopen("/proc/cpuinfo", "r");
-    bool ret = false;
+    FILE *fp;
+    virBitmapPtr flags;
 
-    if (!fp)
-        return false;
+    if (!(fp = fopen("/proc/cpuinfo", "r")))
+        return NULL;
+
+    if (!(flags = virBitmapNewQuiet(VIR_HOST_VALIDATE_CPU_FLAG_LAST)))
+        return NULL;
 
     do {
         char line[1024];
+        char *start;
+        char **tokens;
+        size_t ntokens;
+        size_t i;
 
         if (!fgets(line, sizeof(line), fp))
             break;
 
-        if (strstr(line, name)) {
-            ret = true;
-            break;
+        /* The line we're interested in is marked either as "flags" or
+         * as "Features" depending on the architecture, so check both
+         * prefixes */
+        if (!STRPREFIX(line, "flags") && !STRPREFIX(line, "Features"))
+            continue;
+
+        /* fgets() includes the trailing newline in the output buffer,
+         * so we need to clean that up ourselves. We can safely access
+         * line[strlen(line) - 1] because the checks above would cause
+         * us to skip empty strings */
+        line[strlen(line) - 1] = '\0';
+
+        /* Skip to the separator */
+        if (!(start = strchr(line, ':')))
+            continue;
+
+        /* Split the line using " " as a delimiter. The first token
+         * will always be ":", but that's okay */
+        if (!(tokens = virStringSplitCount(start, " ", 0, &ntokens)))
+            continue;
+
+        /* Go through all flags and check whether one of those we
+         * might want to check for later on is present; if that's
+         * the case, set the relevant bit in the bitmap */
+        for (i = 0; i < ntokens; i++) {
+            int value;
+
+            if ((value = virHostValidateCPUFlagTypeFromString(tokens[i])) >= 0)
+                ignore_value(virBitmapSetBit(flags, value));
         }
+
+        virStringFreeListCount(tokens, ntokens);
     } while (1);
 
     VIR_FORCE_FCLOSE(fp);
 
-    return ret;
+    return flags;
 }
 
 
@@ -359,15 +397,20 @@ int virHostValidateCGroupController(const char *hvname,
 int virHostValidateIOMMU(const char *hvname,
                          virHostValidateLevel level)
 {
+    virBitmapPtr flags;
     struct stat sb;
     const char *bootarg = NULL;
     bool isAMD = false, isIntel = false;
 
-    if (virHostValidateHasCPUFlag("vmx"))
+    flags = virHostValidateGetCPUFlags();
+
+    if (flags && virBitmapIsBitSet(flags, VIR_HOST_VALIDATE_CPU_FLAG_VMX))
         isIntel = true;
-    else if (virHostValidateHasCPUFlag("svm"))
+    else if (flags && virBitmapIsBitSet(flags, VIR_HOST_VALIDATE_CPU_FLAG_SVM))
         isAMD = true;
 
+    virBitmapFree(flags);
+
     virHostMsgCheck(hvname, "%s", _("for device assignment IOMMU support"));
 
     if (isIntel) {

tools/virt-host-validate-common.h

@@ -23,6 +23,8 @@
 # define __VIRT_HOST_VALIDATE_COMMON_H__
 
 # include "internal.h"
+# include "virutil.h"
+# include "virbitmap.h"
 
 typedef enum {
     VIR_HOST_VALIDATE_FAIL,
@@ -32,6 +34,15 @@ typedef enum {
     VIR_HOST_VALIDATE_LAST,
 } virHostValidateLevel;
 
+typedef enum {
+    VIR_HOST_VALIDATE_CPU_FLAG_VMX = 0,
+    VIR_HOST_VALIDATE_CPU_FLAG_SVM,
+
+    VIR_HOST_VALIDATE_CPU_FLAG_LAST,
+} virHostValidateCPUFlag;
+
+VIR_ENUM_DECL(virHostValidateCPUFlag);
+
 extern void virHostMsgSetQuiet(bool quietFlag);
 
 extern void virHostMsgCheck(const char *prefix,
@@ -53,7 +64,7 @@ extern int virHostValidateDeviceAccessible(const char *hvname,
                                            virHostValidateLevel level,
                                            const char *hint);
 
-extern bool virHostValidateHasCPUFlag(const char *name);
+extern virBitmapPtr virHostValidateGetCPUFlags(void);
 
 extern int virHostValidateLinuxKernel(const char *hvname,
                                       int version,

tools/virt-host-validate-qemu.c

@@ -24,14 +24,20 @@
 
 #include "virt-host-validate-qemu.h"
 #include "virt-host-validate-common.h"
+#include "virbitmap.h"
 
 int virHostValidateQEMU(void)
 {
+    virBitmapPtr flags;
     int ret = 0;
 
     virHostMsgCheck("QEMU", "%s", ("for hardware virtualization"));
-    if (virHostValidateHasCPUFlag("svm") ||
-        virHostValidateHasCPUFlag("vmx")) {
+
+    flags = virHostValidateGetCPUFlags();
+
+    if (flags &&
+        (virBitmapIsBitSet(flags, VIR_HOST_VALIDATE_CPU_FLAG_SVM) ||
+         virBitmapIsBitSet(flags, VIR_HOST_VALIDATE_CPU_FLAG_VMX))) {
         virHostMsgPass();
         if (virHostValidateDeviceExists("QEMU", "/dev/kvm",
                                         VIR_HOST_VALIDATE_FAIL,
@@ -48,6 +54,8 @@ int virHostValidateQEMU(void)
                        _("Only emulated CPUs are available, performance will be significantly limited"));
     }
 
+    virBitmapFree(flags);
+
     if (virHostValidateDeviceExists("QEMU", "/dev/vhost-net",
                                     VIR_HOST_VALIDATE_WARN,
                                     _("Load the 'vhost_net' module to improve performance "