This was really... quite broken. After fixing this,
Windows boots with kernel-irqchip=off.

Signed-off-by: Mohamed Mediouni <mohamed@unpredictable.fr>
---
 include/system/whpx-common.h |  1 +
 target/i386/whpx/whpx-all.c  | 54 ++++++++++--------------------------
 2 files changed, 15 insertions(+), 40 deletions(-)

diff --git a/include/system/whpx-common.h b/include/system/whpx-common.h
index 04289afd97..3406c20fec 100644
--- a/include/system/whpx-common.h
+++ b/include/system/whpx-common.h
@@ -4,6 +4,7 @@
 
 struct AccelCPUState {
     bool window_registered;
+    int window_priority;
     bool interruptable;
     bool ready_for_pic_interrupt;
     uint64_t tpr;
diff --git a/target/i386/whpx/whpx-all.c b/target/i386/whpx/whpx-all.c
index 3e006496be..97284b954b 100644
--- a/target/i386/whpx/whpx-all.c
+++ b/target/i386/whpx/whpx-all.c
@@ -371,28 +371,6 @@ static int whpx_set_tsc(CPUState *cpu)
     return 0;
 }
 
-/*
- * The CR8 register in the CPU is mapped to the TPR register of the APIC,
- * however, they use a slightly different encoding. Specifically:
- *
- *     APIC.TPR[bits 7:4] = CR8[bits 3:0]
- *
- * This mechanism is described in section 10.8.6.1 of Volume 3 of Intel 64
- * and IA-32 Architectures Software Developer's Manual.
- *
- * The functions below translate the value of CR8 to TPR and vice versa.
- */
-
-static uint64_t whpx_apic_tpr_to_cr8(uint64_t tpr)
-{
-    return tpr >> 4;
-}
-
-static uint64_t whpx_cr8_to_apic_tpr(uint64_t cr8)
-{
-    return cr8 << 4;
-}
-
 void whpx_set_registers(CPUState *cpu, WHPXStateLevel level)
 {
     struct whpx_state *whpx = &whpx_global;
@@ -421,7 +399,7 @@ void whpx_set_registers(CPUState *cpu, WHPXStateLevel level)
     v86 = (env->eflags & VM_MASK);
     r86 = !(env->cr[0] & CR0_PE_MASK);
 
-    vcpu->tpr = whpx_apic_tpr_to_cr8(cpu_get_apic_tpr(x86_cpu->apic_state));
+    vcpu->tpr = cpu_get_apic_tpr(x86_cpu->apic_state);
     vcpu->apic_base = cpu_get_apic_base(x86_cpu->apic_state);
 
     idx = 0;
@@ -692,17 +670,6 @@ void whpx_get_registers(CPUState *cpu, WHPXStateLevel level)
                      hr);
     }
 
-    if (whpx_irqchip_in_kernel()) {
-        /*
-         * Fetch the TPR value from the emulated APIC. It may get overwritten
-         * below with the value from CR8 returned by
-         * WHvGetVirtualProcessorRegisters().
-         */
-        whpx_apic_get(x86_cpu->apic_state);
-        vcpu->tpr = whpx_apic_tpr_to_cr8(
-            cpu_get_apic_tpr(x86_cpu->apic_state));
-    }
-
     idx = 0;
 
     /* Indexes for first 16 registers match between HV and QEMU definitions */
@@ -751,7 +718,7 @@ void whpx_get_registers(CPUState *cpu, WHPXStateLevel level)
     tpr = vcxt.values[idx++].Reg64;
     if (tpr != vcpu->tpr) {
         vcpu->tpr = tpr;
-        cpu_set_apic_tpr(x86_cpu->apic_state, whpx_cr8_to_apic_tpr(tpr));
+        cpu_set_apic_tpr(x86_cpu->apic_state, tpr);
     }
 
     /* 8 Debug Registers - Skipped */
@@ -1605,6 +1572,7 @@ static void whpx_vcpu_pre_run(CPUState *cpu)
     UINT32 reg_count = 0;
     WHV_REGISTER_VALUE reg_values[3];
     WHV_REGISTER_NAME reg_names[3];
+    int irr = apic_get_highest_priority_irr(x86_cpu->apic_state);
 
     memset(&new_int, 0, sizeof(new_int));
     memset(reg_values, 0, sizeof(reg_values));
@@ -1643,7 +1611,8 @@ static void whpx_vcpu_pre_run(CPUState *cpu)
     /* Get pending hard interruption or replay one that was overwritten */
     if (!whpx_irqchip_in_kernel()) {
         if (!vcpu->interruption_pending &&
-            vcpu->interruptable && (env->eflags & IF_MASK)) {
+            vcpu->interruptable && (env->eflags & IF_MASK)
+            && (irr == -1 || vcpu->tpr < irr)) {
             assert(!new_int.InterruptionPending);
             if (cpu_test_interrupt(cpu, CPU_INTERRUPT_HARD)) {
                 cpu_reset_interrupt(cpu, CPU_INTERRUPT_HARD);
@@ -1690,7 +1659,7 @@ static void whpx_vcpu_pre_run(CPUState *cpu)
      }
 
     /* Sync the TPR to the CR8 if was modified during the intercept */
-    tpr = whpx_apic_tpr_to_cr8(cpu_get_apic_tpr(x86_cpu->apic_state));
+    tpr = cpu_get_apic_tpr(x86_cpu->apic_state);
     if (tpr != vcpu->tpr) {
         vcpu->tpr = tpr;
         reg_values[reg_count].Reg64 = tpr;
@@ -1700,13 +1669,18 @@ static void whpx_vcpu_pre_run(CPUState *cpu)
     }
 
     /* Update the state of the interrupt delivery notification */
-    if (!vcpu->window_registered &&
+    if ((!vcpu->window_registered || vcpu->window_priority < irr) &&
         cpu_test_interrupt(cpu, CPU_INTERRUPT_HARD)) {
+        if (irr == -1) {
+            irr = 0;
+        }
         reg_values[reg_count].DeliverabilityNotifications =
             (WHV_X64_DELIVERABILITY_NOTIFICATIONS_REGISTER) {
-                .InterruptNotification = 1
+                .InterruptNotification = 1,
+                .InterruptPriority = irr
             };
         vcpu->window_registered = 1;
+        vcpu->window_priority = irr;
         reg_names[reg_count] = WHvX64RegisterDeliverabilityNotifications;
         reg_count += 1;
     }
@@ -1737,7 +1711,7 @@ static void whpx_vcpu_post_run(CPUState *cpu)
     if (vcpu->tpr != tpr) {
         vcpu->tpr = tpr;
         bql_lock();
-        cpu_set_apic_tpr(x86_cpu->apic_state, whpx_cr8_to_apic_tpr(vcpu->tpr));
+        cpu_set_apic_tpr(x86_cpu->apic_state, vcpu->tpr);
         bql_unlock();
     }
 
-- 
2.50.1 (Apple Git-155)