From 51290a9442c1b9347c43b2fec34b7aa979d26c77 Mon Sep 17 00:00:00 2001

Message-Id: <51290a9442c1b9347c43b2fec34b7aa979d26c77@dist-git>

From: Jiri Denemark <jdenemar@redhat.com>

Date: Tue, 26 May 2020 10:59:34 +0200

Subject: [PATCH] cpu_x86: Add support for stepping part of CPU signature

MIME-Version: 1.0

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CPU models defined in the cpu_map can use signature/@stepping attribute

to match a limited set of stepping numbers. The value is a bitmap for

bits 0..15 each corresponding to a single stepping value. For example,

stepping='4-6,9' will match 4, 5, 6, and 9. Omitting the attribute is

equivalent to stepping='0-15'.

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>

Reviewed-by: Ján Tomko <jtomko@redhat.com>

(cherry picked from commit c7a27949954d78dc95459758e329fb9c580361bb)

https://bugzilla.redhat.com/show_bug.cgi?id=1840010

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>

Message-Id: <20bd9df72a22a004bb665409ddba20ff89a5b66d.1590483392.git.jdenemar@redhat.com>

Reviewed-by: Ján Tomko <jtomko@redhat.com>

---

 src/cpu/cpu_x86.c | 60 +++++++++++++++++++++++++++++++++++++++--------

 1 file changed, 50 insertions(+), 10 deletions(-)

diff --git a/src/cpu/cpu_x86.c b/src/cpu/cpu_x86.c

index 45a073c1d0..0d81f3d2ae 100644

--- a/src/cpu/cpu_x86.c

+++ b/src/cpu/cpu_x86.c

@@ -125,6 +125,7 @@ typedef struct _virCPUx86Signature virCPUx86Signature;

 struct _virCPUx86Signature {

     unsigned int family;

     unsigned int model;

+    virBitmapPtr stepping;

 };

 typedef struct _virCPUx86Signatures virCPUx86Signatures;

@@ -732,7 +733,17 @@ x86MakeSignature(unsigned int family,

 static uint32_t

 virCPUx86SignatureToCPUID(virCPUx86Signature *sig)

 {

-    return x86MakeSignature(sig->family, sig->model, 0);

+    unsigned int stepping = 0;

+

+    if (sig->stepping) {

+        ssize_t firstBit;

+

+        firstBit = virBitmapNextSetBit(sig->stepping, -1);

+        if (firstBit >= 0)

+            stepping = firstBit;

+    }

+

+    return x86MakeSignature(sig->family, sig->model, stepping);

 }

@@ -767,8 +778,8 @@ x86DataToSignatureFull(const virCPUx86Data *data,

 }

-/* Mask out irrelevant bits (R and Step) from processor signature. */

-#define SIGNATURE_MASK  0x0fff3ff0

+/* Mask out reserved bits from processor signature. */

+#define SIGNATURE_MASK  0x0fff3fff

 static uint32_t

 x86DataToSignature(const virCPUx86Data *data)

@@ -1134,9 +1145,14 @@ virCPUx86SignaturesNew(size_t count)

 static void

 virCPUx86SignaturesFree(virCPUx86SignaturesPtr sigs)

 {

+    size_t i;

+

     if (!sigs)

         return;

+    for (i = 0; i < sigs->count; i++)

+        virBitmapFree(sigs->items[i].stepping);

+

     g_free(sigs->items);

     g_free(sigs);

 }

@@ -1153,8 +1169,12 @@ virCPUx86SignaturesCopy(virCPUx86SignaturesPtr src)

     dst = virCPUx86SignaturesNew(src->count);

-    for (i = 0; i < src->count; i++)

-        dst->items[i] = src->items[i];

+    for (i = 0; i < src->count; i++) {

+        dst->items[i].family = src->items[i].family;

+        dst->items[i].model = src->items[i].model;

+        if (src->items[i].stepping)

+            dst->items[i].stepping = virBitmapNewCopy(src->items[i].stepping);

+    }

     return dst;

 }

@@ -1176,7 +1196,9 @@ virCPUx86SignaturesMatch(virCPUx86SignaturesPtr sigs,

     for (i = 0; i < sigs->count; i++) {

         if (sigs->items[i].family == family &&

-            sigs->items[i].model == model)

+            sigs->items[i].model == model &&

+            (!sigs->items[i].stepping ||

+             virBitmapIsBitSet(sigs->items[i].stepping, stepping)))

             return true;

     }

@@ -1194,9 +1216,15 @@ virCPUx86SignaturesFormat(virCPUx86SignaturesPtr sigs)

         return virBufferContentAndReset(&buf;;

     for (i = 0; i < sigs->count; i++) {

-        virBufferAsprintf(&buf, "(%u,%u,0), ",

+        g_autofree char *stepping = NULL;

+

+        if (sigs->items[i].stepping)

+            stepping = virBitmapFormat(sigs->items[i].stepping);

+

+        virBufferAsprintf(&buf, "(%u,%u,%s), ",

                           sigs->items[i].family,

-                          sigs->items[i].model);

+                          sigs->items[i].model,

+                          stepping ? stepping : "0-15");

     }

     virBufferTrim(&buf, ", ", -1);

@@ -1473,6 +1501,7 @@ x86ModelParseSignatures(virCPUx86ModelPtr model,

     for (i = 0; i < n; i++) {

         virCPUx86Signature *sig = &model->signatures->items[i];

+        g_autofree char *stepping = NULL;

         int rc;

         ctxt->node = nodes[i];

@@ -1492,6 +1521,11 @@ x86ModelParseSignatures(virCPUx86ModelPtr model,

                            model->name);

             return -1;

         }

+

+        stepping = virXPathString("string(@stepping)", ctxt);

+        /* stepping corresponds to 4 bits in 32b signature, see above */

+        if (stepping && virBitmapParse(stepping, &sig->stepping, 16) < 0)

+            return -1;

     }

     ctxt->node = root;

@@ -2090,6 +2124,9 @@ x86Decode(virCPUDefPtr cpu,

     virDomainCapsCPUModelPtr hvModel = NULL;

     g_autofree char *sigs = NULL;

     uint32_t signature;

+    unsigned int sigFamily;

+    unsigned int sigModel;

+    unsigned int sigStepping;

     ssize_t i;

     int rc;

@@ -2103,6 +2140,7 @@ x86Decode(virCPUDefPtr cpu,

     vendor = x86DataToVendor(&data, map);

     signature = x86DataToSignature(&data);

+    virCPUx86SignatureFromCPUID(signature, &sigFamily, &sigModel, &sigStepping);

     x86DataFilterTSX(&data, vendor, map);

@@ -2184,8 +2222,10 @@ x86Decode(virCPUDefPtr cpu,

     sigs = virCPUx86SignaturesFormat(model->signatures);

-    VIR_DEBUG("Using CPU model %s (signatures %s) for CPU with signature %06lx",

-              model->name, NULLSTR(sigs), (unsigned long)signature);

+    VIR_DEBUG("Using CPU model %s with signatures [%s] for "

+              "CPU with signature (%u,%u,%u)",

+              model->name, NULLSTR(sigs),

+              sigFamily, sigModel, sigStepping);

     cpu->model = g_steal_pointer(&cpuModel->model);

     cpu->features = g_steal_pointer(&cpuModel->features);

-- 

2.26.2