fb506e701e
Cluster x2APIC cannot work without KVM's x2apic API when the maximal APIC ID is greater than 8 and only KVM's LAPIC can support x2APIC, so we forbid other APICs and also the old KVM case with less than 9, to simplify the code. There is no point in enabling EIM in forbidden APICs, so we keep it enabled only for the KVM APIC; unconditionally, because making the option depend on KVM version would be a maintanance burden. Old QEMUs would enable eim whenever intremap was on, which would trick guests into thinking that they can enable cluster x2APIC even if any interrupt destination would get clamped to 8 bits. Depending on your configuration, QEMU could notice that the destination LAPIC is not present and report it with a very non-obvious: KVM: injection failed, MSI lost (Operation not permitted) Or the guest could say something about unexpected interrupts, because clamping leads to aliasing so interrupts were being delivered to incorrect VCPUs. KVM_X2APIC_API is the feature that allows us to enable EIM for KVM. QEMU 2.7 allowed EIM whenever interrupt remapping was enabled. In order to keep backward compatibility, we again allow guests to misbehave in non-obvious ways, and make it the default for old machine types. A user can enable the buggy mode it with "x-buggy-eim=on". Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> Reviewed-by: Eduardo Habkost <ehabkost@redhat.com> Reviewed-by: Peter Xu <peterx@redhat.com> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
43 lines
831 B
C
43 lines
831 B
C
/*
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* QEMU KVM x86 specific function stubs
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*
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* Copyright Linaro Limited 2012
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*
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* Author: Peter Maydell <peter.maydell@linaro.org>
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*
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*/
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#include "qemu/osdep.h"
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#include "qemu-common.h"
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#include "cpu.h"
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#include "kvm_i386.h"
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bool kvm_allows_irq0_override(void)
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{
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return 1;
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}
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#ifndef __OPTIMIZE__
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bool kvm_has_smm(void)
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{
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return 1;
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}
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bool kvm_enable_x2apic(void)
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{
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return false;
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}
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/* This function is only called inside conditionals which we
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* rely on the compiler to optimize out when CONFIG_KVM is not
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* defined.
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*/
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uint32_t kvm_arch_get_supported_cpuid(KVMState *env, uint32_t function,
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uint32_t index, int reg)
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{
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abort();
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}
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#endif
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