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b5149e2292
PR KVM does not support running with AIL enabled, and SCV does is not supported with AIL disabled. Fix this by ensuring the SCV facility is disabled with FSCR while a CPU could be running with AIL=0. The PowerNV host supports disabling AIL on a per-CPU basis, so SCV just needs to be disabled when a vCPU is being run. The pSeries machine can only switch AIL on a system-wide basis, so it must disable SCV support at boot if the configuration can potentially run a PR KVM guest. Also ensure a the FSCR[SCV] bit can not be enabled when emulating mtFSCR for the guest. SCV is not emulated for the PR guest at the moment, this just fixes the host crashes. Alternatives considered and rejected: - SCV support can not be disabled by PR KVM after boot, because it is advertised to userspace with HWCAP. - AIL can not be disabled on a per-CPU basis. At least when running on pseries it is a per-LPAR setting. - Support for real-mode SCV vectors will not be added because they are at 0x17000 so making such a large fixed head space causes immediate value limits to be exceeded, requiring a lot rework and more code. - Disabling SCV for any PR KVM possible kernel will cause a slowdown when not using PR KVM. - A boot time option to disable SCV to use PR KVM is user-hostile. - System call instruction emulation for SCV facility unavailable instructions is too complex and old emulation code was subtly broken and removed. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Reviewed-by: Fabiano Rosas <farosas@linux.ibm.com> Link: https://lore.kernel.org/r/20220222064727.2314380-2-npiggin@gmail.com
234 lines
6.9 KiB
Plaintext
234 lines
6.9 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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select INTERVAL_TREE
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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 PPC_64S_HASH_MMU
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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 only available for hash MMU mode and only supports
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guests that use hash MMU mode.
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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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Selecting this option will cause the SCV facility to be
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disabled when the kernel is booted on the pseries platform in
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hash MMU mode (regardless of PR VMs running). When any PR VMs
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are running, "AIL" mode is disabled which may slow interrupts
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and system calls on the 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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