i386/cpu: Add x-vendor-cpuid-only-v2 option for compatibility

Add a compat property "x-vendor-cpuid-only-v2" (for PC machine v10.0
and older) to keep the original behavior. This property will be used
to adjust vendor specific CPUID fields.

Make x-vendor-cpuid-only-v2 depend on x-vendor-cpuid-only. Although
x-vendor-cpuid-only and v2 should be initernal only, QEMU doesn't
support "internal" property. To avoid any other unexpected issues, check
the dependency.

Tested-by: Yi Lai <yi1.lai@intel.com>
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Link: https://lore.kernel.org/r/20250711102143.1622339-8-zhao1.liu@intel.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index a6fa7923688b7abf8feed7fab14b253aef2a3610..7cfa61c9ee616801575e4ded9bfa2ff11b63116d 100644 (file)
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -83,6 +83,7 @@
 
 GlobalProperty pc_compat_10_0[] = {
     { TYPE_X86_CPU, "x-consistent-cache", "false" },
+    { TYPE_X86_CPU, "x-vendor-cpuid-only-v2", "false" },
 };
 const size_t pc_compat_10_0_len = G_N_ELEMENTS(pc_compat_10_0);
 

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index ac22548f47d1651e9882b2c15873860a3a37f96e..630a40d72beaec5722f6fdc4541f8f143fa015f7 100644 (file)
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -8749,6 +8749,16 @@ static void x86_cpu_realizefn(DeviceState *dev, Error **errp)
     tcg_cflags_set(cs, CF_PCREL);
 #endif
 
+    /*
+     * x-vendor-cpuid-only and v2 should be initernal only. But
+     * QEMU doesn't support "internal" property.
+     */
+    if (!cpu->vendor_cpuid_only && cpu->vendor_cpuid_only_v2) {
+        error_setg(errp, "x-vendor-cpuid-only-v2 property "
+                   "depends on x-vendor-cpuid-only");
+        return;
+    }
+
     if (cpu->apic_id == UNASSIGNED_APIC_ID) {
         error_setg(errp, "apic-id property was not initialized properly");
         return;

diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index d3f7c53e30102bbb6e1707524c7f08690184c178..d88481ba8ec3cc5a2d0275bc84493f0f3764f28e 100644 (file)
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -2282,9 +2282,18 @@ struct ArchCPU {
     /* Enable auto level-increase for all CPUID leaves */
     bool full_cpuid_auto_level;
 
-    /* Only advertise CPUID leaves defined by the vendor */
+    /*
+     * Compatibility bits for old machine types (PC machine v6.0 and older).
+     * Only advertise CPUID leaves defined by the vendor.
+     */
     bool vendor_cpuid_only;
 
+    /*
+     * Compatibility bits for old machine types (PC machine v10.0 and older).
+     * Only advertise CPUID leaves defined by the vendor.
+     */
+    bool vendor_cpuid_only_v2;
+
     /* Only advertise TOPOEXT features that AMD defines */
     bool amd_topoext_features_only;