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Provide a config option that controls the workaround added by commit63279eeb7f("KVM: PPC: Book3S HV: Always save guest pmu for guest capable of nesting"). The option defaults to y for now, but is expected to go away within a few releases. Nested capable guests running with the earlier commit1782663897("KVM: PPC: Book3S HV Nested: Reflect guest PMU in-use to L0 when guest SPRs are live") will now indicate the PMU in-use status of their guests, which means the parent does not need to unconditionally save the PMU for nested capable guests. After this latest round of performance optimisations, this option costs about 540 cycles or 10% entry/exit performance on a POWER9 nested-capable guest. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Reviewed-by: Fabiano Rosas <farosas@linux.ibm.com> References:1782663897("KVM: PPC: Book3S HV Nested: Reflect guest PMU in-use to L0 when guest SPRs are live") Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20211123095231.1036501-11-npiggin@gmail.com
223 lines
6.5 KiB
Plaintext
223 lines
6.5 KiB
Plaintext
# SPDX-License-Identifier: GPL-2.0
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#
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# KVM configuration
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#
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source "virt/kvm/Kconfig"
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menuconfig VIRTUALIZATION
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bool "Virtualization"
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help
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Say Y here to get to see options for using your Linux host to run
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other operating systems inside virtual machines (guests).
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This option alone does not add any kernel code.
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If you say N, all options in this submenu will be skipped and
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disabled.
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if VIRTUALIZATION
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config KVM
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bool
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select PREEMPT_NOTIFIERS
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select HAVE_KVM_EVENTFD
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select HAVE_KVM_VCPU_ASYNC_IOCTL
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select SRCU
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select KVM_VFIO
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select IRQ_BYPASS_MANAGER
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select HAVE_KVM_IRQ_BYPASS
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config KVM_BOOK3S_HANDLER
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bool
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config KVM_BOOK3S_32_HANDLER
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bool
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select KVM_BOOK3S_HANDLER
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select KVM_MMIO
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config KVM_BOOK3S_64_HANDLER
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bool
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select KVM_BOOK3S_HANDLER
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config KVM_BOOK3S_PR_POSSIBLE
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bool
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select KVM_MMIO
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select MMU_NOTIFIER
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config KVM_BOOK3S_HV_POSSIBLE
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bool
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config KVM_BOOK3S_32
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tristate "KVM support for PowerPC book3s_32 processors"
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depends on PPC_BOOK3S_32 && !SMP && !PTE_64BIT
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select KVM
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select KVM_BOOK3S_32_HANDLER
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select KVM_BOOK3S_PR_POSSIBLE
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select PPC_FPU
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help
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Support running unmodified book3s_32 guest kernels
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in virtual machines on book3s_32 host processors.
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This module provides access to the hardware capabilities through
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a character device node named /dev/kvm.
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If unsure, say N.
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config KVM_BOOK3S_64
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tristate "KVM support for PowerPC book3s_64 processors"
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depends on PPC_BOOK3S_64
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select KVM_BOOK3S_64_HANDLER
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select KVM
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select KVM_BOOK3S_PR_POSSIBLE if !KVM_BOOK3S_HV_POSSIBLE
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select SPAPR_TCE_IOMMU if IOMMU_SUPPORT && (PPC_PSERIES || PPC_POWERNV)
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help
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Support running unmodified book3s_64 and book3s_32 guest kernels
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in virtual machines on book3s_64 host processors.
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This module provides access to the hardware capabilities through
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a character device node named /dev/kvm.
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If unsure, say N.
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config KVM_BOOK3S_64_HV
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tristate "KVM for POWER7 and later using hypervisor mode in host"
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depends on KVM_BOOK3S_64 && PPC_POWERNV
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select KVM_BOOK3S_HV_POSSIBLE
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select MMU_NOTIFIER
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select CMA
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help
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Support running unmodified book3s_64 guest kernels in
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virtual machines on POWER7 and newer processors that have
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hypervisor mode available to the host.
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If you say Y here, KVM will use the hardware virtualization
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facilities of POWER7 (and later) processors, meaning that
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guest operating systems will run at full hardware speed
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using supervisor and user modes. However, this also means
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that KVM is not usable under PowerVM (pHyp), is only usable
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on POWER7 or later processors, and cannot emulate a
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different processor from the host processor.
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If unsure, say N.
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config KVM_BOOK3S_64_PR
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tristate "KVM support without using hypervisor mode in host"
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depends on KVM_BOOK3S_64
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select KVM_BOOK3S_PR_POSSIBLE
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help
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Support running guest kernels in virtual machines on processors
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without using hypervisor mode in the host, by running the
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guest in user mode (problem state) and emulating all
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privileged instructions and registers.
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This is not as fast as using hypervisor mode, but works on
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machines where hypervisor mode is not available or not usable,
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and can emulate processors that are different from the host
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processor, including emulating 32-bit processors on a 64-bit
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host.
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config KVM_BOOK3S_HV_EXIT_TIMING
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bool "Detailed timing for hypervisor real-mode code"
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depends on KVM_BOOK3S_HV_POSSIBLE && DEBUG_FS
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help
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Calculate time taken for each vcpu in the real-mode guest entry,
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exit, and interrupt handling code, plus time spent in the guest
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and in nap mode due to idle (cede) while other threads are still
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in the guest. The total, minimum and maximum times in nanoseconds
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together with the number of executions are reported in debugfs in
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kvm/vm#/vcpu#/timings. The overhead is of the order of 30 - 40
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ns per exit on POWER8.
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If unsure, say N.
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config KVM_BOOK3S_HV_NESTED_PMU_WORKAROUND
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bool "Nested L0 host workaround for L1 KVM host PMU handling bug" if EXPERT
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depends on KVM_BOOK3S_HV_POSSIBLE
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default !EXPERT
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help
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Old nested HV capable Linux guests have a bug where they don't
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reflect the PMU in-use status of their L2 guest to the L0 host
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while the L2 PMU registers are live. This can result in loss
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of L2 PMU register state, causing perf to not work correctly in
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L2 guests.
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Selecting this option for the L0 host implements a workaround for
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those buggy L1s which saves the L2 state, at the cost of performance
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in all nested-capable guest entry/exit.
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config KVM_BOOKE_HV
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bool
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config KVM_EXIT_TIMING
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bool "Detailed exit timing"
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depends on KVM_E500V2 || KVM_E500MC
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help
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Calculate elapsed time for every exit/enter cycle. A per-vcpu
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report is available in debugfs kvm/vm#_vcpu#_timing.
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The overhead is relatively small, however it is not recommended for
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production environments.
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If unsure, say N.
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config KVM_E500V2
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bool "KVM support for PowerPC E500v2 processors"
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depends on E500 && !PPC_E500MC
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select KVM
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select KVM_MMIO
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select MMU_NOTIFIER
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help
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Support running unmodified E500 guest kernels in virtual machines on
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E500v2 host processors.
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This module provides access to the hardware capabilities through
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a character device node named /dev/kvm.
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If unsure, say N.
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config KVM_E500MC
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bool "KVM support for PowerPC E500MC/E5500/E6500 processors"
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depends on PPC_E500MC
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select KVM
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select KVM_MMIO
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select KVM_BOOKE_HV
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select MMU_NOTIFIER
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help
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Support running unmodified E500MC/E5500/E6500 guest kernels in
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virtual machines on E500MC/E5500/E6500 host processors.
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This module provides access to the hardware capabilities through
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a character device node named /dev/kvm.
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If unsure, say N.
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config KVM_MPIC
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bool "KVM in-kernel MPIC emulation"
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depends on KVM && E500
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select HAVE_KVM_IRQCHIP
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select HAVE_KVM_IRQFD
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select HAVE_KVM_IRQ_ROUTING
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select HAVE_KVM_MSI
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help
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Enable support for emulating MPIC devices inside the
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host kernel, rather than relying on userspace to emulate.
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Currently, support is limited to certain versions of
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Freescale's MPIC implementation.
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config KVM_XICS
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bool "KVM in-kernel XICS emulation"
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depends on KVM_BOOK3S_64 && !KVM_MPIC
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select HAVE_KVM_IRQCHIP
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select HAVE_KVM_IRQFD
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default y
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help
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Include support for the XICS (eXternal Interrupt Controller
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Specification) interrupt controller architecture used on
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IBM POWER (pSeries) servers.
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config KVM_XIVE
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bool
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default y
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depends on KVM_XICS && PPC_XIVE_NATIVE && KVM_BOOK3S_HV_POSSIBLE
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endif # VIRTUALIZATION
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