From 2c933ac6a883606b85f8cf271bfb40379d077e97 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Mon, 1 Mar 2021 12:14:14 +0100 Subject: [PATCH] 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 Signed-off-by: Paolo Bonzini --- docs/system/deprecated.rst | 7 +++++++ hw/intc/apic.c | 6 ++++++ 2 files changed, 13 insertions(+) diff --git a/docs/system/deprecated.rst b/docs/system/deprecated.rst index 561c916da2..fcf0ca4068 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 3ada22f427..f4f50f974e 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);