Commit 32452bac6d for qemu.org

commit 32452bac6d991e9778dd7a9fb2b3eed3a2b23d71
Author: Mohamed Mediouni <mohamed@unpredictable.fr>
Date:   Wed Aug 12 10:28:10 2026 +0200

    hw/i386: fw_cfg: do not set VMX feature control on WHPX

    Hyper-V doesn't allow setting this bit on build 26100.

    Signed-off-by: Mohamed Mediouni <mohamed@unpredictable.fr>
    Link: https://lore.kernel.org/r/20260812082814.27217-3-mohamed@unpredictable.fr
    Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/hw/i386/fw_cfg.c b/hw/i386/fw_cfg.c
index d422302c1c..5903994a7c 100644
--- a/hw/i386/fw_cfg.c
+++ b/hw/i386/fw_cfg.c
@@ -13,6 +13,8 @@
  */

 #include "qemu/osdep.h"
+#include "system/mshv.h"
+#include "system/whpx.h"
 #include "system/numa.h"
 #include "hw/acpi/acpi.h"
 #include "hw/acpi/aml-build.h"
@@ -182,8 +184,15 @@ void fw_cfg_build_feature_control(MachineState *ms, FWCfgState *fw_cfg)
     uint64_t *val;

     cpu_x86_cpuid(env, 1, 0, &unused, &unused, &ecx, &edx);
-    if (ecx & CPUID_EXT_VMX) {
-        feature_control_bits |= FEATURE_CONTROL_VMXON_ENABLED_OUTSIDE_SMX;
+
+    /*
+     * Hyper-V in 26100 disallows this bit to be set.
+     * Otherwise a #GP gets raised.
+     */
+    if (!(whpx_enabled())) {
+        if (ecx & CPUID_EXT_VMX) {
+            feature_control_bits |= FEATURE_CONTROL_VMXON_ENABLED_OUTSIDE_SMX;
+        }
     }

     if ((edx & (CPUID_EXT2_MCE | CPUID_EXT2_MCA)) ==