qemu-devel
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [PATCH] i386/cpu: Introduce enable_cpuid_0x1f to force exposing CPUI


From: Xiaoyao Li
Subject: Re: [PATCH] i386/cpu: Introduce enable_cpuid_0x1f to force exposing CPUID 0x1f
Date: Thu, 8 Aug 2024 21:59:07 +0800
User-agent: Mozilla Thunderbird

On 8/8/2024 6:09 PM, Zhao Liu wrote:
Hi Xiaoyao,

Patch is generally fine for me. Just a few nits:

On Fri, Aug 02, 2024 at 03:24:26AM -0400, Xiaoyao Li wrote:
diff --git a/include/hw/i386/topology.h b/include/hw/i386/topology.h
index dff49fce1154..b63bce2f4c82 100644
--- a/include/hw/i386/topology.h
+++ b/include/hw/i386/topology.h
@@ -207,13 +207,4 @@ static inline apic_id_t 
x86_apicid_from_cpu_idx(X86CPUTopoInfo *topo_info,
      return x86_apicid_from_topo_ids(topo_info, &topo_ids);
  }
-/*
- * Check whether there's extended topology level (module or die)?
- */
-static inline bool x86_has_extended_topo(unsigned long *topo_bitmap)
-{
-    return test_bit(CPU_TOPO_LEVEL_MODULE, topo_bitmap) ||
-           test_bit(CPU_TOPO_LEVEL_DIE, topo_bitmap);
-}
-

[snip]

+/*
+ * Check whether there's v2 extended topology level (module or die)?
+ */
+bool x86_has_v2_extended_topo(X86CPU *cpu)
+{
+    if (cpu->enable_cpuid_0x1f) {
+        return true;
+    }
+
+    return test_bit(CPU_TOPO_LEVEL_MODULE, cpu->env.avail_cpu_topo) ||
+           test_bit(CPU_TOPO_LEVEL_DIE, cpu->env.avail_cpu_topo);
+}
+

I suggest to decouple 0x1f enablement and extended topo check, since as
the comment of CPUTopoLevel said:

/*
  * CPUTopoLevel is the general i386 topology hierarchical representation,
  * ordered by increasing hierarchical relationship.
  * Its enumeration value is not bound to the type value of Intel (CPUID[0x1F])
  * or AMD (CPUID[0x80000026]).
  */

The topology enumeration is generic and is not bound to the vendor.

I don't quit get your point. All the current usages of x86_has_extended_topo() are for CPUID leaf 0x1f, which is an Intel specific leaf.

Are you saying x86_has_extended_topo() will be used for leaf 0x80000026 for AMD as well?

or maybe I misunderstand the meaning "extend_topo". The extend_topo just means the topo level of module and die, and the topo level of smt and core are non-extended? If so, this is new to me, could I ask where the definitions come from? or just QEMU defines them itself?

[snip]

diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index c6cc035df3d8..211a42ffbfa6 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -2110,6 +2110,9 @@ struct ArchCPU {
      /* Compatibility bits for old machine types: */
      bool enable_cpuid_0xb;
+ /* Force to expose cpuid 0x1f */

Maybe "Force to enable cpuid 0x1f"?

I can change to it.

+    bool enable_cpuid_0x1f;
+
      /* Enable auto level-increase for all CPUID leaves */
      bool full_cpuid_auto_level;i

Regards,
Zhao





reply via email to

[Prev in Thread] Current Thread [Next in Thread]