Commit 3b124791bd for qemu.org

commit 3b124791bdcea9d5a2fd74db5dcd5ba24cceb843
Author: Mohamed Mediouni <mohamed@unpredictable.fr>
Date:   Wed Apr 22 23:41:58 2026 +0200

    whpx: i386: disable kernel-irqchip on Windows 10 when PIC enabled

    Move WHvCapabilityCodeProcessorPerfmonFeatures queries
    as that's how we distinguish if on a legacy OS.

    Now that Windows guests are booting, disable kernel-irqchip=on
    by default for Windows 10 when the PIC is enabled.

    Signed-off-by: Mohamed Mediouni <mohamed@unpredictable.fr>
    Link: https://lore.kernel.org/r/20260422214225.2242-11-mohamed@unpredictable.fr
    Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/target/i386/whpx/whpx-all.c b/target/i386/whpx/whpx-all.c
index 03c146dfb8..ab8e97787f 100644
--- a/target/i386/whpx/whpx-all.c
+++ b/target/i386/whpx/whpx-all.c
@@ -2523,6 +2523,13 @@ int whpx_accel_init(AccelState *as, MachineState *ms)
         0x80000002, 0x80000003, 0x80000004, 0x80000007, 0x80000008,
         0x8000000A, 0x80000021, 0x80000022, 0xC0000000, 0xC0000001};

+    X86MachineState *x86ms = X86_MACHINE(ms);
+    bool pic_enabled = false;
+
+    if (x86ms->pic == ON_OFF_AUTO_ON || x86ms->pic == ON_OFF_AUTO_AUTO) {
+        pic_enabled = true;
+    }
+
     whpx = &whpx_global;

     if (!init_whp_dispatch()) {
@@ -2594,6 +2601,35 @@ int whpx_accel_init(AccelState *as, MachineState *ms)
         goto error;
     }

+    /* Enable supported performance monitoring capabilities */
+    hr = whp_dispatch.WHvGetCapability(
+        WHvCapabilityCodeProcessorPerfmonFeatures, &perfmon_features,
+        sizeof(WHV_PROCESSOR_PERFMON_FEATURES), &whpx_cap_size);
+    /*
+     * Relying on this is a crutch to maintain Windows 10 support.
+     *
+     * WHvCapabilityCodeProcessorPerfmonFeatures and
+     * WHvPartitionPropertyCodeSyntheticProcessorFeaturesBanks
+     * are implemented starting from Windows Server 2022 (build 20348).
+     */
+    if (FAILED(hr)) {
+        warn_report("WHPX: Failed to get performance "
+                    "monitoring features, hr=%08lx", hr);
+        is_modern_os = false;
+    } else {
+        hr = whp_dispatch.WHvSetPartitionProperty(
+                whpx->partition,
+                WHvPartitionPropertyCodeProcessorPerfmonFeatures,
+                &perfmon_features,
+                sizeof(WHV_PROCESSOR_PERFMON_FEATURES));
+        if (FAILED(hr)) {
+            error_report("WHPX: Failed to set performance "
+                         "monitoring features, hr=%08lx", hr);
+            ret = -EINVAL;
+            goto error;
+        }
+    }
+
     /*
      * Error out if WHP doesn't support apic emulation and user is requiring
      * it.
@@ -2606,8 +2642,9 @@ int whpx_accel_init(AccelState *as, MachineState *ms)
         goto error;
     }

-    if (whpx->kernel_irqchip_allowed && features.LocalApicEmulation &&
-        whp_dispatch.WHvSetVirtualProcessorInterruptControllerState2) {
+    if (whpx->kernel_irqchip_allowed && !(whpx_is_legacy_os() && pic_enabled
+        && !whpx->kernel_irqchip_required) && features.LocalApicEmulation
+        && whp_dispatch.WHvSetVirtualProcessorInterruptControllerState2) {
         WHV_X64_LOCAL_APIC_EMULATION_MODE mode =
             WHvX64LocalApicEmulationModeX2Apic;
         hr = whp_dispatch.WHvSetPartitionProperty(
@@ -2669,34 +2706,6 @@ int whpx_accel_init(AccelState *as, MachineState *ms)
         goto error;
     }

-    /* Enable supported performance monitoring capabilities */
-    hr = whp_dispatch.WHvGetCapability(
-        WHvCapabilityCodeProcessorPerfmonFeatures, &perfmon_features,
-        sizeof(WHV_PROCESSOR_PERFMON_FEATURES), &whpx_cap_size);
-    /*
-     * Relying on this is a crutch to maintain Windows 10 support.
-     *
-     * WHvCapabilityCodeProcessorPerfmonFeatures and
-     * WHvPartitionPropertyCodeSyntheticProcessorFeaturesBanks
-     * are implemented starting from Windows Server 2022 (build 20348).
-     */
-    if (FAILED(hr)) {
-        warn_report("WHPX: Failed to get performance "
-                    "monitoring features, hr=%08lx", hr);
-        is_modern_os = false;
-    } else {
-        hr = whp_dispatch.WHvSetPartitionProperty(
-                whpx->partition,
-                WHvPartitionPropertyCodeProcessorPerfmonFeatures,
-                &perfmon_features,
-                sizeof(WHV_PROCESSOR_PERFMON_FEATURES));
-        if (FAILED(hr)) {
-            error_report("WHPX: Failed to set performance "
-                         "monitoring features, hr=%08lx", hr);
-            ret = -EINVAL;
-            goto error;
-        }
-    }

     /* Enable synthetic processor features */
     WHV_SYNTHETIC_PROCESSOR_FEATURES_BANKS synthetic_features;