Patchwork [2/6] target-i386: cpu: separate feature string parsing from CPU model lookup

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Submitter Eduardo Habkost
Date Dec. 4, 2012, 7:34 p.m.
Message ID <1354649683-9078-3-git-send-email-ehabkost@redhat.com>
Download mbox | patch
Permalink /patch/203729/
State New
Headers show

Comments

Eduardo Habkost - Dec. 4, 2012, 7:34 p.m.
Instead of using parsing the whole cpu_model string inside
cpu_x86_find_by_name(), first split it into the CPU model name and the
full feature string, then parse the feature string into pieces.

When using CPU model classes, those two pieces of information will be
used at different moments (CPU model name will be used to find CPU
class, feature string will be used after CPU object was created), so
making the split in two steps will make it easier to refactor the code
later.

This should also help on the CPU properties work, that will just need to
replace the cpu_x86_parse_featurestr() logic (and can keep the CPU model
lookup code as-is).

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
Changes v1 -> v2:
 - Coding style changes
 - Replace "goto error" with "return -1"

Changes v2 -> v3:
 - Fix memory leak on handling of errors form object_property_set_str()
---
 target-i386/cpu.c | 69 ++++++++++++++++++++++++++++++++++++-------------------
 1 file changed, 46 insertions(+), 23 deletions(-)
Igor Mammedov - Dec. 4, 2012, 7:47 p.m.
On Tue,  4 Dec 2012 17:34:39 -0200
Eduardo Habkost <ehabkost@redhat.com> wrote:

> Instead of using parsing the whole cpu_model string inside
> cpu_x86_find_by_name(), first split it into the CPU model name and the
> full feature string, then parse the feature string into pieces.
> 
> When using CPU model classes, those two pieces of information will be
> used at different moments (CPU model name will be used to find CPU
> class, feature string will be used after CPU object was created), so
> making the split in two steps will make it easier to refactor the code
> later.
> 
> This should also help on the CPU properties work, that will just need to
> replace the cpu_x86_parse_featurestr() logic (and can keep the CPU model
> lookup code as-is).
> 
> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> ---
> Changes v1 -> v2:
>  - Coding style changes
>  - Replace "goto error" with "return -1"
> 
> Changes v2 -> v3:
>  - Fix memory leak on handling of errors form object_property_set_str()
> ---
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Andreas Färber - Dec. 5, 2012, 3:58 p.m.
Am 04.12.2012 20:34, schrieb Eduardo Habkost:
> Instead of using parsing the whole cpu_model string inside

Dropped "using".

> cpu_x86_find_by_name(), first split it into the CPU model name and the
> full feature string, then parse the feature string into pieces.
[...]
> diff --git a/target-i386/cpu.c b/target-i386/cpu.c
> index 7afe839..70ba323 100644
> --- a/target-i386/cpu.c
> +++ b/target-i386/cpu.c
> @@ -1208,25 +1208,10 @@ static void x86_cpuid_set_tsc_freq(Object *obj, Visitor *v, void *opaque,
>      cpu->env.tsc_khz = value / 1000;
>  }
>  
> -static int cpu_x86_find_by_name(x86_def_t *x86_cpu_def, const char *cpu_model)
> +static int cpu_x86_find_by_name(x86_def_t *x86_cpu_def, const char *name)
>  {
> -    unsigned int i;
>      x86_def_t *def;
>  
> -    char *s = g_strdup(cpu_model);
> -    char *featurestr, *name = strtok(s, ",");
> -    /* Features to be added*/
[...]
> @@ -1235,16 +1220,37 @@ static int cpu_x86_find_by_name(x86_def_t *x86_cpu_def, const char *cpu_model)
>      if (kvm_enabled() && name && strcmp(name, "host") == 0) {
>          kvm_cpu_fill_host(x86_cpu_def);
>      } else if (!def) {
> -        goto error;
> +        return -1;
>      } else {
>          memcpy(x86_cpu_def, def, sizeof(*def));
>      }
>  
> +    return 0;
> +}
> +
> +/* Parse "+feature,-feature,feature=foo" CPU feature string
> + */
> +static int cpu_x86_parse_featurestr(x86_def_t *x86_cpu_def, char *features)
> +{
> +    unsigned int i;
> +    char *featurestr; /* Single 'key=value" string being parsed */
> +    /* Features to be added*/

I took the liberty of adding a space above by editing patches 1 & 2.

Also, in Linux, multi-level topics such as "PPC: KVM: " seem to be
common, whereas in QEMU we've been using paths ("tcg/ppc: "); Anthony
has once used "isa: pic: " when he meant affecting both isa and pic
(8f04ee0882aec9fe91fb70f767edf5dacff59835), so since this does not touch
on the QOM cpu.c that I usually label "cpu: ", in a previous case I have
edited your patch as "target-i386/cpu: ", but since this subject
redundantly mentions CPU later on I'm dropping it. Hope this explains
the rationale! Generally I found the GNOME guidelines pretty convincing:
https://live.gnome.org/Git/CommitMessages
(capitalizing after the lowercase topic makes the main message stand out
when reading through shortlogs IMO)

Thanks, applied patches 1-2 to qom-cpu:
https://github.com/afaerber/qemu-cpu/commits/qom-cpu

Andreas

Patch

diff --git a/target-i386/cpu.c b/target-i386/cpu.c
index 7afe839..70ba323 100644
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -1208,25 +1208,10 @@  static void x86_cpuid_set_tsc_freq(Object *obj, Visitor *v, void *opaque,
     cpu->env.tsc_khz = value / 1000;
 }
 
-static int cpu_x86_find_by_name(x86_def_t *x86_cpu_def, const char *cpu_model)
+static int cpu_x86_find_by_name(x86_def_t *x86_cpu_def, const char *name)
 {
-    unsigned int i;
     x86_def_t *def;
 
-    char *s = g_strdup(cpu_model);
-    char *featurestr, *name = strtok(s, ",");
-    /* Features to be added*/
-    uint32_t plus_features = 0, plus_ext_features = 0;
-    uint32_t plus_ext2_features = 0, plus_ext3_features = 0;
-    uint32_t plus_kvm_features = kvm_default_features, plus_svm_features = 0;
-    uint32_t plus_7_0_ebx_features = 0;
-    /* Features to be removed */
-    uint32_t minus_features = 0, minus_ext_features = 0;
-    uint32_t minus_ext2_features = 0, minus_ext3_features = 0;
-    uint32_t minus_kvm_features = 0, minus_svm_features = 0;
-    uint32_t minus_7_0_ebx_features = 0;
-    uint32_t numvalue;
-
     for (def = x86_defs; def; def = def->next) {
         if (name && !strcmp(name, def->name)) {
             break;
@@ -1235,16 +1220,37 @@  static int cpu_x86_find_by_name(x86_def_t *x86_cpu_def, const char *cpu_model)
     if (kvm_enabled() && name && strcmp(name, "host") == 0) {
         kvm_cpu_fill_host(x86_cpu_def);
     } else if (!def) {
-        goto error;
+        return -1;
     } else {
         memcpy(x86_cpu_def, def, sizeof(*def));
     }
 
+    return 0;
+}
+
+/* Parse "+feature,-feature,feature=foo" CPU feature string
+ */
+static int cpu_x86_parse_featurestr(x86_def_t *x86_cpu_def, char *features)
+{
+    unsigned int i;
+    char *featurestr; /* Single 'key=value" string being parsed */
+    /* Features to be added*/
+    uint32_t plus_features = 0, plus_ext_features = 0;
+    uint32_t plus_ext2_features = 0, plus_ext3_features = 0;
+    uint32_t plus_kvm_features = kvm_default_features, plus_svm_features = 0;
+    uint32_t plus_7_0_ebx_features = 0;
+    /* Features to be removed */
+    uint32_t minus_features = 0, minus_ext_features = 0;
+    uint32_t minus_ext2_features = 0, minus_ext3_features = 0;
+    uint32_t minus_kvm_features = 0, minus_svm_features = 0;
+    uint32_t minus_7_0_ebx_features = 0;
+    uint32_t numvalue;
+
     add_flagname_to_bitmaps("hypervisor", &plus_features,
             &plus_ext_features, &plus_ext2_features, &plus_ext3_features,
             &plus_kvm_features, &plus_svm_features,  &plus_7_0_ebx_features);
 
-    featurestr = strtok(NULL, ",");
+    featurestr = features ? strtok(features, ",") : NULL;
 
     while (featurestr) {
         char *val;
@@ -1378,11 +1384,9 @@  static int cpu_x86_find_by_name(x86_def_t *x86_cpu_def, const char *cpu_model)
     if (x86_cpu_def->cpuid_7_0_ebx_features && x86_cpu_def->level < 7) {
         x86_cpu_def->level = 7;
     }
-    g_free(s);
     return 0;
 
 error:
-    g_free(s);
     return -1;
 }
 
@@ -1492,11 +1496,25 @@  int cpu_x86_register(X86CPU *cpu, const char *cpu_model)
     CPUX86State *env = &cpu->env;
     x86_def_t def1, *def = &def1;
     Error *error = NULL;
+    char *name, *features;
+    gchar **model_pieces;
 
     memset(def, 0, sizeof(*def));
 
-    if (cpu_x86_find_by_name(def, cpu_model) < 0)
-        return -1;
+    model_pieces = g_strsplit(cpu_model, ",", 2);
+    if (!model_pieces[0]) {
+        goto error;
+    }
+    name = model_pieces[0];
+    features = model_pieces[1];
+
+    if (cpu_x86_find_by_name(def, name) < 0) {
+        goto error;
+    }
+
+    if (cpu_x86_parse_featurestr(def, features) < 0) {
+        goto error;
+    }
     if (def->vendor1) {
         env->cpuid_vendor1 = def->vendor1;
         env->cpuid_vendor2 = def->vendor2;
@@ -1553,9 +1571,14 @@  int cpu_x86_register(X86CPU *cpu, const char *cpu_model)
     if (error) {
         fprintf(stderr, "%s\n", error_get_pretty(error));
         error_free(error);
-        return -1;
+        goto error;
     }
+
+    g_strfreev(model_pieces);
     return 0;
+error:
+    g_strfreev(model_pieces);
+    return -1;
 }
 
 #if !defined(CONFIG_USER_ONLY)