[PATCH] KVM: remove support for kernel-irqchip=off

[Paolo Bonzini <pbonzini@redhat.com>]

-machine kernel-irqchip=off is broken for many guest OSes; kernel-irqchip=split
is the replacement that works, so remove the deprecated support for the former.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 docs/about/deprecated.rst       |  7 -------
 docs/about/removed-features.rst |  7 +++++++
 hw/i386/amd_iommu.c             |  2 +-
 hw/i386/intel_iommu.c           |  4 ++--
 include/hw/i386/apic_internal.h |  2 +-
 target/i386/cpu-sysemu.c        | 15 +++++++++++----
 6 files changed, 22 insertions(+), 15 deletions(-)

diff --git a/docs/about/deprecated.rst b/docs/about/deprecated.rst
index b28f50b22fa9..f1575a52cb4d 100644
--- a/docs/about/deprecated.rst
+++ b/docs/about/deprecated.rst
@@ -58,13 +58,6 @@ and will cause a warning.
 The replacement for the ``nodelay`` short-form boolean option is ``nodelay=on``
 rather than ``delay=off``.
 
-Userspace local APIC with KVM (x86, since 6.0)
-''''''''''''''''''''''''''''''''''''''''''''''
-
-Using ``-M kernel-irqchip=off`` with x86 machine types that include a local
-APIC is deprecated.  The ``split`` setting is supported, as is using
-``-M kernel-irqchip=off`` with the ISA PC machine type.
-
 hexadecimal sizes with scaling multipliers (since 6.0)
 ''''''''''''''''''''''''''''''''''''''''''''''''''''''
 
diff --git a/docs/about/removed-features.rst b/docs/about/removed-features.rst
index 91c9dce6d6e0..76c2178cd39e 100644
--- a/docs/about/removed-features.rst
+++ b/docs/about/removed-features.rst
@@ -625,6 +625,13 @@ MIPS "Trap-and-Emulate" KVM support (removed in 8.0)
 The MIPS "Trap-and-Emulate" KVM host and guest support was removed
 from Linux in 2021, and is not supported anymore by QEMU either.
 
+Userspace local APIC with KVM (x86, removed 8.0)
+''''''''''''''''''''''''''''''''''''''''''''''''
+
+``-M kernel-irqchip=off`` cannot be used on KVM if the CPU model includes
+a local APIC.  The ``split`` setting is supported, as is using ``-M
+kernel-irqchip=off`` when the CPU does not have a local APIC.
+
 System emulator machines
 ------------------------
 
diff --git a/hw/i386/amd_iommu.c b/hw/i386/amd_iommu.c
index 725f69095b9e..bcd016f5c5a5 100644
--- a/hw/i386/amd_iommu.c
+++ b/hw/i386/amd_iommu.c
@@ -1368,7 +1368,7 @@ static MemTxResult amdvi_mem_ir_write(void *opaque, hwaddr addr,
         return MEMTX_ERROR;
     }
 
-    apic_get_class()->send_msi(&to);
+    apic_get_class(NULL)->send_msi(&to);
 
     trace_amdvi_mem_ir_write(to.address, to.data);
     return MEMTX_OK;
diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index a08ee85edf2a..98a5c304a7d7 100644
--- a/hw/i386/intel_iommu.c
+++ b/hw/i386/intel_iommu.c
@@ -396,7 +396,7 @@ static void vtd_generate_interrupt(IntelIOMMUState *s, hwaddr mesg_addr_reg,
 
     trace_vtd_irq_generate(msi.address, msi.data);
 
-    apic_get_class()->send_msi(&msi);
+    apic_get_class(NULL)->send_msi(&msi);
 }
 
 /* Generate a fault event to software via MSI if conditions are met.
@@ -3529,7 +3529,7 @@ static MemTxResult vtd_mem_ir_write(void *opaque, hwaddr addr,
         return MEMTX_ERROR;
     }
 
-    apic_get_class()->send_msi(&to);
+    apic_get_class(NULL)->send_msi(&to);
 
     return MEMTX_OK;
 }
diff --git a/include/hw/i386/apic_internal.h b/include/hw/i386/apic_internal.h
index c175e7e71816..968b6648b3a4 100644
--- a/include/hw/i386/apic_internal.h
+++ b/include/hw/i386/apic_internal.h
@@ -226,6 +226,6 @@ static inline int apic_get_bit(uint32_t *tab, int index)
     return !!(tab[i] & mask);
 }
 
-APICCommonClass *apic_get_class(void);
+APICCommonClass *apic_get_class(Error **errp);
 
 #endif /* QEMU_APIC_INTERNAL_H */
diff --git a/target/i386/cpu-sysemu.c b/target/i386/cpu-sysemu.c
index fc97213a73cf..28115edf44f7 100644
--- a/target/i386/cpu-sysemu.c
+++ b/target/i386/cpu-sysemu.c
@@ -247,12 +247,16 @@ void x86_cpu_machine_reset_cb(void *opaque)
     cpu_reset(CPU(cpu));
 }
 
-APICCommonClass *apic_get_class(void)
+APICCommonClass *apic_get_class(Error **errp)
 {
     const char *apic_type = "apic";
 
     /* TODO: in-kernel irqchip for hvf */
-    if (kvm_apic_in_kernel()) {
+    if (kvm_enabled()) {
+        if (!kvm_apic_in_kernel()) {
+            error_setg(errp, "KVM does not support userspace APIC");
+            return NULL;
+        }
         apic_type = "kvm-apic";
     } else if (xen_enabled()) {
         apic_type = "xen-apic";
@@ -266,10 +270,13 @@ APICCommonClass *apic_get_class(void)
 void x86_cpu_apic_create(X86CPU *cpu, Error **errp)
 {
     APICCommonState *apic;
-    ObjectClass *apic_class = OBJECT_CLASS(apic_get_class());
+    APICCommonClass *apic_class = apic_get_class(errp);
 
-    cpu->apic_state = DEVICE(object_new_with_class(apic_class));
+    if (!apic_class) {
+        return;
+    }
 
+    cpu->apic_state = DEVICE(object_new_with_class(OBJECT_CLASS(apic_class)));
     object_property_add_child(OBJECT(cpu), "lapic",
                               OBJECT(cpu->apic_state));
     object_unref(OBJECT(cpu->apic_state));
-- 
2.38.1