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authorPaolo Bonzini <pbonzini@redhat.com>2021-03-01 12:14:14 +0100
committerPaolo Bonzini <pbonzini@redhat.com>2021-03-06 11:41:54 +0100
commit2c933ac6a883606b85f8cf271bfb40379d077e97 (patch)
treec5db6ab7750d90dae226389b177e5fff440bd09c
parentc6986f16a7022ccfb73d91bc7676c8e1d15e5342 (diff)
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KVM: x86: deprecate -M kernel-irqchip=off except for -M isapc
The userspace local APIC is basically untested and does not support many features such as TSC deadline timer, x2APIC or PV spinlocks. On the other hand, the PIT and IOAPIC are okay as they are not tied to the processor and are tested with -M kernel-irqchip=split. Therefore, deprecate the local APIC and, with it, limit -M kernel-irqchip=off to the ISA PC machine type, which does not have a local APIC at all. Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
-rw-r--r--docs/system/deprecated.rst7
-rw-r--r--hw/intc/apic.c6
2 files changed, 13 insertions, 0 deletions
diff --git a/docs/system/deprecated.rst b/docs/system/deprecated.rst
index 561c916..fcf0ca4 100644
--- a/docs/system/deprecated.rst
+++ b/docs/system/deprecated.rst
@@ -153,6 +153,13 @@ The ``-writeconfig`` option is not able to serialize the entire contents
of the QEMU command line. It is thus considered a failed experiment
and deprecated, with no current replacement.
+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.
+
QEMU Machine Protocol (QMP) commands
------------------------------------
diff --git a/hw/intc/apic.c b/hw/intc/apic.c
index 3ada22f..f4f50f9 100644
--- a/hw/intc/apic.c
+++ b/hw/intc/apic.c
@@ -25,6 +25,7 @@
#include "hw/intc/i8259.h"
#include "hw/pci/msi.h"
#include "qemu/host-utils.h"
+#include "sysemu/kvm.h"
#include "trace.h"
#include "hw/i386/apic-msidef.h"
#include "qapi/error.h"
@@ -875,6 +876,11 @@ static void apic_realize(DeviceState *dev, Error **errp)
return;
}
+ if (kvm_enabled()) {
+ warn_report("Userspace local APIC is deprecated for KVM.");
+ warn_report("Do not use kernel-irqchip except for the -M isapc machine type.");
+ }
+
memory_region_init_io(&s->io_memory, OBJECT(s), &apic_io_ops, s, "apic-msi",
APIC_SPACE_SIZE);