kernel/linux.git/virt/kvm/Kconfig, branch v6.19.12

KVM: Make support for kvm_arch_vcpu_async_ioctl() mandatory

2025-11-05T19:03:10+00:00

Implement kvm_arch_vcpu_async_ioctl() "natively" in x86 and arm64 instead of relying on an #ifdef'd stub, and drop HAVE_KVM_VCPU_ASYNC_IOCTL in anticipation of using the API on x86. Once x86 uses the API, providing a stub for one architecture and having all other architectures opt-in requires more code than simply implementing the API in the lone holdout. Eliminating the Kconfig will also reduce churn if the API is renamed in the future (spoiler alert). No functional change intended. Acked-by: Claudio Imbrenda Reviewed-by: Yan Zhao Tested-by: Yan Zhao Tested-by: Kai Huang Link: https://patch.msgid.link/20251030200951.3402865-2-seanjc@google.com Signed-off-by: Sean Christopherson

Merge tag 'kvm-x86-fixes-6.18-rc2' of https://github.com/kvm-x86/linux into HEAD

2025-10-18T08:25:43+00:00

KVM x86 fixes for 6.18: - Expand the KVM_PRE_FAULT_MEMORY selftest to add a regression test for the bug fixed by commit 3ccbf6f47098 ("KVM: x86/mmu: Return -EAGAIN if userspace deletes/moves memslot during prefault") - Don't try to get PMU capabbilities from perf when running a CPU with hybrid CPUs/PMUs, as perf will rightly WARN. - Rework KVM_CAP_GUEST_MEMFD_MMAP (newly introduced in 6.18) into a more generic KVM_CAP_GUEST_MEMFD_FLAGS - Add a guest_memfd INIT_SHARED flag and require userspace to explicitly set said flag to initialize memory as SHARED, irrespective of MMAP. The behavior merged in 6.18 is that enabling mmap() implicitly initializes memory as SHARED, which would result in an ABI collision for x86 CoCo VMs as their memory is currently always initialized PRIVATE. - Allow mmap() on guest_memfd for x86 CoCo VMs, i.e. on VMs with private memory, to enable testing such setups, i.e. to hopefully flush out any other lurking ABI issues before 6.18 is officially released. - Add testcases to the guest_memfd selftest to cover guest_memfd without MMAP, and host userspace accesses to mmap()'d private memory.

KVM: Explicitly mark KVM_GUEST_MEMFD as depending on KVM_GENERIC_MMU_NOTIFIER

2025-10-10T21:25:24+00:00

Add KVM_GENERIC_MMU_NOTIFIER as a dependency for selecting KVM_GUEST_MEMFD, as guest_memfd relies on kvm_mmu_invalidate_{begin,end}(), which are defined if and only if the generic mmu_notifier implementation is enabled. The missing dependency is currently benign as s390 is the only KVM arch that doesn't utilize the generic mmu_notifier infrastructure, and s390 doesn't currently support guest_memfd. Fixes: a7800aa80ea4 ("KVM: Add KVM_CREATE_GUEST_MEMFD ioctl() for guest-specific backing memory") Reviewed-by: David Hildenbrand Link: https://lore.kernel.org/r/20251003232606.4070510-5-seanjc@google.com Signed-off-by: Sean Christopherson

Merge tag 'hyperv-next-signed-20251006' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux

2025-10-07T15:40:15+00:00

Pull hyperv updates from Wei Liu: - Unify guest entry code for KVM and MSHV (Sean Christopherson) - Switch Hyper-V MSI domain to use msi_create_parent_irq_domain() (Nam Cao) - Add CONFIG_HYPERV_VMBUS and limit the semantics of CONFIG_HYPERV (Mukesh Rathor) - Add kexec/kdump support on Azure CVMs (Vitaly Kuznetsov) - Deprecate hyperv_fb in favor of Hyper-V DRM driver (Prasanna Kumar T S M) - Miscellaneous enhancements, fixes and cleanups (Abhishek Tiwari, Alok Tiwari, Nuno Das Neves, Wei Liu, Roman Kisel, Michael Kelley) * tag 'hyperv-next-signed-20251006' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux: hyperv: Remove the spurious null directive line MAINTAINERS: Mark hyperv_fb driver Obsolete fbdev/hyperv_fb: deprecate this in favor of Hyper-V DRM driver Drivers: hv: Make CONFIG_HYPERV bool Drivers: hv: Add CONFIG_HYPERV_VMBUS option Drivers: hv: vmbus: Fix typos in vmbus_drv.c Drivers: hv: vmbus: Fix sysfs output format for ring buffer index Drivers: hv: vmbus: Clean up sscanf format specifier in target_cpu_store() x86/hyperv: Switch to msi_create_parent_irq_domain() mshv: Use common "entry virt" APIs to do work in root before running guest entry: Rename "kvm" entry code assets to "virt" to genericize APIs entry/kvm: KVM: Move KVM details related to signal/-EINTR into KVM proper mshv: Handle NEED_RESCHED_LAZY before transferring to guest x86/hyperv: Add kexec/kdump support on Azure CVMs Drivers: hv: Simplify data structures for VMBus channel close message Drivers: hv: util: Cosmetic changes for hv_utils_transport.c mshv: Add support for a new parent partition configuration clocksource: hyper-v: Skip unnecessary checks for the root partition hyperv: Add missing field to hv_output_map_device_interrupt

entry: Rename "kvm" entry code assets to "virt" to genericize APIs

2025-09-30T22:50:18+00:00

Rename the "kvm" entry code files and Kconfigs to use generic "virt" nomenclature so that the code can be reused by other hypervisors (or rather, their root/dom0 partition drivers), without incorrectly suggesting the code somehow relies on and/or involves KVM. No functional change intended. Signed-off-by: Sean Christopherson Reviewed-by: Thomas Gleixner Reviewed-by: Joel Fernandes Signed-off-by: Wei Liu

KVM: Rename CONFIG_KVM_GENERIC_PRIVATE_MEM to CONFIG_HAVE_KVM_ARCH_GMEM_POPULATE

2025-08-27T08:35:00+00:00

The original name was vague regarding its functionality. This Kconfig option specifically enables and gates the kvm_gmem_populate() function, which is responsible for populating a GPA range with guest data. The new name, HAVE_KVM_ARCH_GMEM_POPULATE, describes the purpose of the option: to enable arch-specific guest_memfd population mechanisms. It also follows the same pattern as the other HAVE_KVM_ARCH_* configuration options. This improves clarity for developers and ensures the name accurately reflects the functionality it controls, especially as guest_memfd support expands beyond purely "private" memory scenarios. Temporarily keep KVM_GENERIC_PRIVATE_MEM as an x86-only config so as to minimize churn, and to hopefully make it easier to see what features require HAVE_KVM_ARCH_GMEM_POPULATE. On that note, omit GMEM_POPULATE for KVM_X86_SW_PROTECTED_VM, as regular ol' memset() suffices for software-protected VMs. As for KVM_GENERIC_PRIVATE_MEM, a future change will select KVM_GUEST_MEMFD for all 64-bit KVM builds, at which point the intermediate config will become obsolete and can/will be dropped. Reviewed-by: Ira Weiny Reviewed-by: Gavin Shan Reviewed-by: Shivank Garg Reviewed-by: Vlastimil Babka Co-developed-by: David Hildenbrand Signed-off-by: David Hildenbrand Signed-off-by: Fuad Tabba Reviewed-by: Xiaoyao Li Co-developed-by: Sean Christopherson Signed-off-by: Sean Christopherson Message-ID: <20250729225455.670324-6-seanjc@google.com> Signed-off-by: Paolo Bonzini

KVM: Rename CONFIG_KVM_PRIVATE_MEM to CONFIG_KVM_GUEST_MEMFD

2025-08-27T08:34:59+00:00

Rename the Kconfig option CONFIG_KVM_PRIVATE_MEM to CONFIG_KVM_GUEST_MEMFD. The original name implied that the feature only supported "private" memory. However, CONFIG_KVM_PRIVATE_MEM enables guest_memfd in general, which is not exclusively for private memory. Subsequent patches in this series will add guest_memfd support for non-CoCo VMs, whose memory is not private. Renaming the Kconfig option to CONFIG_KVM_GUEST_MEMFD more accurately reflects its broader scope as the main Kconfig option for all guest_memfd-backed memory. This provides clearer semantics for the option and avoids confusion as new features are introduced. Reviewed-by: Ira Weiny Reviewed-by: Gavin Shan Reviewed-by: Shivank Garg Reviewed-by: Vlastimil Babka Reviewed-by: Xiaoyao Li Co-developed-by: David Hildenbrand Signed-off-by: David Hildenbrand Signed-off-by: Fuad Tabba Signed-off-by: Sean Christopherson Message-ID: <20250729225455.670324-2-seanjc@google.com> Signed-off-by: Paolo Bonzini

KVM: Allow building irqbypass.ko as as module when kvm.ko is a module

2025-04-04T11:07:40+00:00

Convert HAVE_KVM_IRQ_BYPASS into a tristate so that selecting IRQ_BYPASS_MANAGER follows KVM={m,y}, i.e. doesn't force irqbypass.ko to be built-in. Note, PPC allows building KVM as a module, but selects HAVE_KVM_IRQ_BYPASS from a boolean Kconfig, i.e. KVM PPC unnecessarily forces irqbpass.ko to be built-in. But that flaw is a longstanding PPC specific issue. Fixes: 61df71ee992d ("kvm: move "select IRQ_BYPASS_MANAGER" to common code") Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson Message-ID: <20250315024623.2363994-1-seanjc@google.com> Signed-off-by: Paolo Bonzini

KVM: Allow lockless walk of SPTEs when handing aging mmu_notifier event

2025-02-14T15:16:35+00:00

It is possible to correctly do aging without taking the KVM MMU lock, or while taking it for read; add a Kconfig to let architectures do so. Architectures that select KVM_MMU_LOCKLESS_AGING are responsible for correctness. Suggested-by: Yu Zhao Signed-off-by: James Houghton Reviewed-by: David Matlack Link: https://lore.kernel.org/r/20250204004038.1680123-3-jthoughton@google.com [sean: massage shortlog+changelog, fix Kconfig goof and shorten name] Signed-off-by: Sean Christopherson

KVM: Allow arch code to elide TLB flushes when aging a young page

2024-10-30T22:25:40+00:00

Add a Kconfig to allow architectures to opt-out of a TLB flush when a young page is aged, as invalidating TLB entries is not functionally required on most KVM-supported architectures. Stale TLB entries can result in false negatives and theoretically lead to suboptimal reclaim, but in practice all observations have been that the performance gained by skipping TLB flushes outweighs any performance lost by reclaiming hot pages. E.g. the primary MMUs for x86 RISC-V, s390, and PPC Book3S elide the TLB flush for ptep_clear_flush_young(), and arm64's MMU skips the trailing DSB that's required for ordering (presumably because there are optimizations related to eliding other TLB flushes when doing make-before-break). Link: https://lore.kernel.org/r/20241011021051.1557902-18-seanjc@google.com Signed-off-by: Sean Christopherson