KVM_CAP_IRQ_ROUTING has been available for x86 since Linux 2.6.33.
We can make it a requirement since that was more than ten years ago.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 hw/i386/fw_cfg.c       |  2 +-
 hw/i386/kvm/apic.c     |  4 +---
 hw/i386/microvm.c      |  2 +-
 hw/i386/pc.c           |  2 +-
 target/i386/kvm-stub.c |  5 -----
 target/i386/kvm.c      | 14 ++++----------
 target/i386/kvm_i386.h |  1 -
 7 files changed, 8 insertions(+), 22 deletions(-)

diff --git a/hw/i386/fw_cfg.c b/hw/i386/fw_cfg.c
index 33441ad484..e92e17fa07 100644
--- a/hw/i386/fw_cfg.c
+++ b/hw/i386/fw_cfg.c
@@ -123,7 +123,7 @@ FWCfgState *fw_cfg_arch_create(MachineState *ms,
     fw_cfg_add_bytes(fw_cfg, FW_CFG_ACPI_TABLES,
                      acpi_tables, acpi_tables_len);
 #endif
-    fw_cfg_add_i32(fw_cfg, FW_CFG_IRQ0_OVERRIDE, kvm_allows_irq0_override());
+    fw_cfg_add_i32(fw_cfg, FW_CFG_IRQ0_OVERRIDE, true);
 
     fw_cfg_add_bytes(fw_cfg, FW_CFG_E820_TABLE,
                      &e820_reserve, sizeof(e820_reserve));
diff --git a/hw/i386/kvm/apic.c b/hw/i386/kvm/apic.c
index 4eb2d77b87..284c0da6cd 100644
--- a/hw/i386/kvm/apic.c
+++ b/hw/i386/kvm/apic.c
@@ -225,9 +225,7 @@ static void kvm_apic_realize(DeviceState *dev, Error **errp)
     memory_region_init_io(&s->io_memory, OBJECT(s), &kvm_apic_io_ops, s,
                           "kvm-apic-msi", APIC_SPACE_SIZE);
 
-    if (kvm_has_gsi_routing()) {
-        msi_nonbroken = true;
-    }
+    msi_nonbroken = true;
 }
 
 static void kvm_apic_unrealize(DeviceState *dev)
diff --git a/hw/i386/microvm.c b/hw/i386/microvm.c
index aedcae3426..d4bcc28471 100644
--- a/hw/i386/microvm.c
+++ b/hw/i386/microvm.c
@@ -225,7 +225,7 @@ static void microvm_memory_init(MicrovmMachineState *mms)
     fw_cfg_add_i16(fw_cfg, FW_CFG_NB_CPUS, machine->smp.cpus);
     fw_cfg_add_i16(fw_cfg, FW_CFG_MAX_CPUS, machine->smp.max_cpus);
     fw_cfg_add_i64(fw_cfg, FW_CFG_RAM_SIZE, (uint64_t)machine->ram_size);
-    fw_cfg_add_i32(fw_cfg, FW_CFG_IRQ0_OVERRIDE, kvm_allows_irq0_override());
+    fw_cfg_add_i32(fw_cfg, FW_CFG_IRQ0_OVERRIDE, true);
     fw_cfg_add_bytes(fw_cfg, FW_CFG_E820_TABLE,
                      &e820_reserve, sizeof(e820_reserve));
     fw_cfg_add_file(fw_cfg, "etc/e820", e820_table,
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index da2ebc3fa0..9759d8acae 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -825,7 +825,7 @@ void pc_guest_info_init(PCMachineState *pcms)
     MachineState *ms = MACHINE(pcms);
     X86MachineState *x86ms = X86_MACHINE(pcms);
 
-    x86ms->apic_xrupt_override = kvm_allows_irq0_override();
+    x86ms->apic_xrupt_override = true;
     pcms->numa_nodes = ms->numa_state->num_nodes;
     pcms->node_mem = g_malloc0(pcms->numa_nodes *
                                     sizeof *pcms->node_mem);
diff --git a/target/i386/kvm-stub.c b/target/i386/kvm-stub.c
index 872ef7df4c..92f49121b8 100644
--- a/target/i386/kvm-stub.c
+++ b/target/i386/kvm-stub.c
@@ -13,11 +13,6 @@
 #include "cpu.h"
 #include "kvm_i386.h"
 
-bool kvm_allows_irq0_override(void)
-{
-    return 1;
-}
-
 #ifndef __OPTIMIZE__
 bool kvm_has_smm(void)
 {
diff --git a/target/i386/kvm.c b/target/i386/kvm.c
index 595e822161..3996cf9764 100644
--- a/target/i386/kvm.c
+++ b/target/i386/kvm.c
@@ -153,11 +153,6 @@ bool kvm_has_exception_payload(void)
     return has_exception_payload;
 }
 
-bool kvm_allows_irq0_override(void)
-{
-    return !kvm_irqchip_in_kernel() || kvm_has_gsi_routing();
-}
-
 static bool kvm_x2apic_api_set_flags(uint64_t flags)
 {
     KVMState *s = KVM_STATE(current_accel());
@@ -4569,12 +4564,11 @@ bool kvm_arch_stop_on_emulation_error(CPUState *cs)
 void kvm_arch_init_irq_routing(KVMState *s)
 {
     if (!kvm_check_extension(s, KVM_CAP_IRQ_ROUTING)) {
-        /* If kernel can't do irq routing, interrupt source
-         * override 0->2 cannot be set up as required by HPET.
-         * So we have to disable it.
-         */
-        no_hpet = 1;
+        error_report("Your kernel is too old.  This version of QEMU requires "
+		     "KVM_CAP_IRQ_ROUTING support.");
+        exit(1);
     }
+
     /* We know at this point that we're using the in-kernel
      * irqchip, so we can use irqfds, and on x86 we know
      * we can use msi via irqfd and GSI routing.
diff --git a/target/i386/kvm_i386.h b/target/i386/kvm_i386.h
index 0fce4e51d2..a4a619cebb 100644
--- a/target/i386/kvm_i386.h
+++ b/target/i386/kvm_i386.h
@@ -32,7 +32,6 @@
 
 #endif  /* CONFIG_KVM */
 
-bool kvm_allows_irq0_override(void);
 bool kvm_has_smm(void);
 bool kvm_has_adjust_clock(void);
 bool kvm_has_adjust_clock_stable(void);
-- 
2.26.2