f10a570b09
Add a Kconfig entry to set the maximum number of vCPUs per KVM guest and set the default value to 4096 when MAXSMP is enabled, as there are use cases that want to create more than the currently allowed 1024 vCPUs and are more than happy to eat the memory overhead. The Hyper-V TLFS doesn't allow more than 64 sparse banks, i.e. allows a maximum of 4096 virtual CPUs. Cap KVM's maximum number of virtual CPUs to 4096 to avoid exceeding Hyper-V's limit as KVM support for Hyper-V is unconditional, and alternatives like dynamically disabling Hyper-V enlightenments that rely on sparse banks would require non-trivial code changes. Suggested-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Kyle Meyer <kyle.meyer@hpe.com> Link: https://lore.kernel.org/r/20230824215244.3897419-1-kyle.meyer@hpe.com [sean: massage changelog with --verbose, document #ifdef mess] Signed-off-by: Sean Christopherson <seanjc@google.com>
169 lines
4.6 KiB
Plaintext
169 lines
4.6 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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depends on HAVE_KVM || X86
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default y
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help
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Say Y here to get to see options for using your Linux host to run other
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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 disabled.
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if VIRTUALIZATION
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config KVM
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tristate "Kernel-based Virtual Machine (KVM) support"
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depends on HAVE_KVM
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depends on HIGH_RES_TIMERS
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depends on X86_LOCAL_APIC
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select PREEMPT_NOTIFIERS
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select MMU_NOTIFIER
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select HAVE_KVM_IRQCHIP
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select HAVE_KVM_PFNCACHE
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select HAVE_KVM_IRQFD
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select HAVE_KVM_DIRTY_RING_TSO
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select HAVE_KVM_DIRTY_RING_ACQ_REL
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select IRQ_BYPASS_MANAGER
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select HAVE_KVM_IRQ_BYPASS
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select HAVE_KVM_IRQ_ROUTING
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select HAVE_KVM_EVENTFD
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select KVM_ASYNC_PF
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select USER_RETURN_NOTIFIER
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select KVM_MMIO
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select SCHED_INFO
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select PERF_EVENTS
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select GUEST_PERF_EVENTS
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select HAVE_KVM_MSI
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select HAVE_KVM_CPU_RELAX_INTERCEPT
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select HAVE_KVM_NO_POLL
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select KVM_XFER_TO_GUEST_WORK
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select KVM_GENERIC_DIRTYLOG_READ_PROTECT
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select KVM_VFIO
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select INTERVAL_TREE
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select HAVE_KVM_PM_NOTIFIER if PM
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select KVM_GENERIC_HARDWARE_ENABLING
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help
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Support hosting fully virtualized guest machines using hardware
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virtualization extensions. You will need a fairly recent
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processor equipped with virtualization extensions. You will also
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need to select one or more of the processor modules below.
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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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To compile this as a module, choose M here: the module
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will be called kvm.
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If unsure, say N.
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config KVM_WERROR
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bool "Compile KVM with -Werror"
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# KASAN may cause the build to fail due to larger frames
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default y if X86_64 && !KASAN
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# We use the dependency on !COMPILE_TEST to not be enabled
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# blindly in allmodconfig or allyesconfig configurations
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depends on KVM
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depends on (X86_64 && !KASAN) || !COMPILE_TEST
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depends on EXPERT
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help
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Add -Werror to the build flags for KVM.
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If in doubt, say "N".
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config KVM_INTEL
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tristate "KVM for Intel (and compatible) processors support"
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depends on KVM && IA32_FEAT_CTL
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help
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Provides support for KVM on processors equipped with Intel's VT
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extensions, a.k.a. Virtual Machine Extensions (VMX).
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To compile this as a module, choose M here: the module
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will be called kvm-intel.
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config X86_SGX_KVM
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bool "Software Guard eXtensions (SGX) Virtualization"
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depends on X86_SGX && KVM_INTEL
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help
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Enables KVM guests to create SGX enclaves.
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This includes support to expose "raw" unreclaimable enclave memory to
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guests via a device node, e.g. /dev/sgx_vepc.
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If unsure, say N.
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config KVM_AMD
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tristate "KVM for AMD processors support"
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depends on KVM && (CPU_SUP_AMD || CPU_SUP_HYGON)
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help
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Provides support for KVM on AMD processors equipped with the AMD-V
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(SVM) extensions.
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To compile this as a module, choose M here: the module
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will be called kvm-amd.
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config KVM_AMD_SEV
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def_bool y
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bool "AMD Secure Encrypted Virtualization (SEV) support"
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depends on KVM_AMD && X86_64
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depends on CRYPTO_DEV_SP_PSP && !(KVM_AMD=y && CRYPTO_DEV_CCP_DD=m)
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help
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Provides support for launching Encrypted VMs (SEV) and Encrypted VMs
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with Encrypted State (SEV-ES) on AMD processors.
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config KVM_SMM
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bool "System Management Mode emulation"
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default y
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depends on KVM
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help
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Provides support for KVM to emulate System Management Mode (SMM)
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in virtual machines. This can be used by the virtual machine
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firmware to implement UEFI secure boot.
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If unsure, say Y.
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config KVM_XEN
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bool "Support for Xen hypercall interface"
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depends on KVM
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help
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Provides KVM support for the hosting Xen HVM guests and
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passing Xen hypercalls to userspace.
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If in doubt, say "N".
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config KVM_PROVE_MMU
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bool "Prove KVM MMU correctness"
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depends on DEBUG_KERNEL
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depends on KVM
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depends on EXPERT
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help
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Enables runtime assertions in KVM's MMU that are too costly to enable
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in anything remotely resembling a production environment, e.g. this
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gates code that verifies a to-be-freed page table doesn't have any
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present SPTEs.
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If in doubt, say "N".
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config KVM_EXTERNAL_WRITE_TRACKING
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bool
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config KVM_MAX_NR_VCPUS
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int "Maximum number of vCPUs per KVM guest"
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depends on KVM
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range 1024 4096
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default 4096 if MAXSMP
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default 1024
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help
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Set the maximum number of vCPUs per KVM guest. Larger values will increase
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the memory footprint of each KVM guest, regardless of how many vCPUs are
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created for a given VM.
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endif # VIRTUALIZATION
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