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This can be used in two modes. There is an atomic mode where the cached mapping is accessed while holding the rwlock, and a mode where the physical address is used by a vCPU in guest mode. For the latter case, an invalidation will wake the vCPU with the new KVM_REQ_GPC_INVALIDATE, and the architecture will need to refresh any caches it still needs to access before entering guest mode again. Only one vCPU can be targeted by the wake requests; it's simple enough to make it wake all vCPUs or even a mask but I don't see a use case for that additional complexity right now. Invalidation happens from the invalidate_range_start MMU notifier, which needs to be able to sleep in order to wake the vCPU and wait for it. This means that revalidation potentially needs to "wait" for the MMU operation to complete and the invalidate_range_end notifier to be invoked. Like the vCPU when it takes a page fault in that period, we just spin — fixing that in a future patch by implementing an actual *wait* may be another part of shaving this particularly hirsute yak. As noted in the comments in the function itself, the only case where the invalidate_range_start notifier is expected to be called *without* being able to sleep is when the OOM reaper is killing the process. In that case, we expect the vCPU threads already to have exited, and thus there will be nothing to wake, and no reason to wait. So we clear the KVM_REQUEST_WAIT bit and send the request anyway, then complain loudly if there actually *was* anything to wake up. Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Message-Id: <20211210163625.2886-3-dwmw2@infradead.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
139 lines
3.7 KiB
Plaintext
139 lines
3.7 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
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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 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 SRCU
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select INTERVAL_TREE
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select HAVE_KVM_PM_NOTIFIER if PM
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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
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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_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_MMU_AUDIT
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bool "Audit KVM MMU"
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depends on KVM && TRACEPOINTS
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help
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This option adds a R/W kVM module parameter 'mmu_audit', which allows
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auditing of KVM MMU events at runtime.
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config KVM_EXTERNAL_WRITE_TRACKING
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bool
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endif # VIRTUALIZATION
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