KVM: Make KVM_MEM_GUEST_MEMFD mutually exclusive with KVM_MEM_READONLY Disallow creating read-only memslots that support GUEST_MEMFD, as GUEST_MEMFD is fundamentally incompatible with KVM's semantics for read-only memslots. Read-only memslots allow the userspace VMM to emulate option ROMs by filling the backing memory with readable, executable code and data, while triggering emulated MMIO on writes. GUEST_MEMFD doesn't currently support writes from userspace and KVM doesn't support emulated MMIO on private accesses, i.e. the guest can only ever read zeros, and writes will always be treated as errors. Cc: Fuad Tabba <tabba@google.com> Cc: Michael Roth <michael.roth@amd.com> Cc: Isaku Yamahata <isaku.yamahata@gmail.com> Cc: Yu Zhang <yu.c.zhang@linux.intel.com> Cc: Chao Peng <chao.p.peng@linux.intel.com> Fixes: a7800aa80ea4 ("KVM: Add KVM_CREATE_GUEST_MEMFD ioctl() for guest-specific backing memory") Link: https://lore.kernel.org/r/20240222190612.2942589-2-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc@google.com>
Merge tag 'for-linus' of git://git./virt/kvm/kvm Pull kvm updates from Paolo Bonzini: "Generic: - Use memdup_array_user() to harden against overflow. - Unconditionally advertise KVM_CAP_DEVICE_CTRL for all architectures. - Clean up Kconfigs that all KVM architectures were selecting - New functionality around "guest_memfd", a new userspace API that creates an anonymous file and returns a file descriptor that refers to it. guest_memfd files are bound to their owning virtual machine, cannot be mapped, read, or written by userspace, and cannot be resized. guest_memfd files do however support PUNCH_HOLE, which can be used to switch a memory area between guest_memfd and regular anonymous memory. - New ioctl KVM_SET_MEMORY_ATTRIBUTES allowing userspace to specify per-page attributes for a given page of guest memory; right now the only attribute is whether the guest expects to access memory via guest_memfd or not, which in Confidential SVMs backed by SEV-SNP, TDX or ARM64 pKVM is checked by firmware or hypervisor that guarantees confidentiality (AMD PSP, Intel TDX module, or EL2 in the case of pKVM). x86: - Support for "software-protected VMs" that can use the new guest_memfd and page attributes infrastructure. This is mostly useful for testing, since there is no pKVM-like infrastructure to provide a meaningfully reduced TCB. - Fix a relatively benign off-by-one error when splitting huge pages during CLEAR_DIRTY_LOG. - Fix a bug where KVM could incorrectly test-and-clear dirty bits in non-leaf TDP MMU SPTEs if a racing thread replaces a huge SPTE with a non-huge SPTE. - Use more generic lockdep assertions in paths that don't actually care about whether the caller is a reader or a writer. - let Xen guests opt out of having PV clock reported as "based on a stable TSC", because some of them don't expect the "TSC stable" bit (added to the pvclock ABI by KVM, but never set by Xen) to be set. - Revert a bogus, made-up nested SVM consistency check for TLB_CONTROL. - Advertise flush-by-ASID support for nSVM unconditionally, as KVM always flushes on nested transitions, i.e. always satisfies flush requests. This allows running bleeding edge versions of VMware Workstation on top of KVM. - Sanity check that the CPU supports flush-by-ASID when enabling SEV support. - On AMD machines with vNMI, always rely on hardware instead of intercepting IRET in some cases to detect unmasking of NMIs - Support for virtualizing Linear Address Masking (LAM) - Fix a variety of vPMU bugs where KVM fail to stop/reset counters and other state prior to refreshing the vPMU model. - Fix a double-overflow PMU bug by tracking emulated counter events using a dedicated field instead of snapshotting the "previous" counter. If the hardware PMC count triggers overflow that is recognized in the same VM-Exit that KVM manually bumps an event count, KVM would pend PMIs for both the hardware-triggered overflow and for KVM-triggered overflow. - Turn off KVM_WERROR by default for all configs so that it's not inadvertantly enabled by non-KVM developers, which can be problematic for subsystems that require no regressions for W=1 builds. - Advertise all of the host-supported CPUID bits that enumerate IA32_SPEC_CTRL "features". - Don't force a masterclock update when a vCPU synchronizes to the current TSC generation, as updating the masterclock can cause kvmclock's time to "jump" unexpectedly, e.g. when userspace hotplugs a pre-created vCPU. - Use RIP-relative address to read kvm_rebooting in the VM-Enter fault paths, partly as a super minor optimization, but mostly to make KVM play nice with position independent executable builds. - Guard KVM-on-HyperV's range-based TLB flush hooks with an #ifdef on CONFIG_HYPERV as a minor optimization, and to self-document the code. - Add CONFIG_KVM_HYPERV to allow disabling KVM support for HyperV "emulation" at build time. ARM64: - LPA2 support, adding 52bit IPA/PA capability for 4kB and 16kB base granule sizes. Branch shared with the arm64 tree. - Large Fine-Grained Trap rework, bringing some sanity to the feature, although there is more to come. This comes with a prefix branch shared with the arm64 tree. - Some additional Nested Virtualization groundwork, mostly introducing the NV2 VNCR support and retargetting the NV support to that version of the architecture. - A small set of vgic fixes and associated cleanups. Loongarch: - Optimization for memslot hugepage checking - Cleanup and fix some HW/SW timer issues - Add LSX/LASX (128bit/256bit SIMD) support RISC-V: - KVM_GET_REG_LIST improvement for vector registers - Generate ISA extension reg_list using macros in get-reg-list selftest - Support for reporting steal time along with selftest s390: - Bugfixes Selftests: - Fix an annoying goof where the NX hugepage test prints out garbage instead of the magic token needed to run the test. - Fix build errors when a header is delete/moved due to a missing flag in the Makefile. - Detect if KVM bugged/killed a selftest's VM and print out a helpful message instead of complaining that a random ioctl() failed. - Annotate the guest printf/assert helpers with __printf(), and fix the various bugs that were lurking due to lack of said annotation" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (185 commits) x86/kvm: Do not try to disable kvmclock if it was not enabled KVM: x86: add missing "depends on KVM" KVM: fix direction of dependency on MMU notifiers KVM: introduce CONFIG_KVM_COMMON KVM: arm64: Add missing memory barriers when switching to pKVM's hyp pgd KVM: arm64: vgic-its: Avoid potential UAF in LPI translation cache RISC-V: KVM: selftests: Add get-reg-list test for STA registers RISC-V: KVM: selftests: Add steal_time test support RISC-V: KVM: selftests: Add guest_sbi_probe_extension RISC-V: KVM: selftests: Move sbi_ecall to processor.c RISC-V: KVM: Implement SBI STA extension RISC-V: KVM: Add support for SBI STA registers RISC-V: KVM: Add support for SBI extension registers RISC-V: KVM: Add SBI STA info to vcpu_arch RISC-V: KVM: Add steal-update vcpu request RISC-V: KVM: Add SBI STA extension skeleton RISC-V: paravirt: Implement steal-time support RISC-V: Add SBI STA extension definitions RISC-V: paravirt: Add skeleton for pv-time support RISC-V: KVM: Fix indentation in kvm_riscv_vcpu_set_reg_csr() ...
Merge tag 'vfs-6.8.misc' of git://git./linux/kernel/git/vfs/vfs Pull misc vfs updates from Christian Brauner: "This contains the usual miscellaneous features, cleanups, and fixes for vfs and individual fses. Features: - Add Jan Kara as VFS reviewer - Show correct device and inode numbers in proc/<pid>/maps for vma files on stacked filesystems. This is now easily doable thanks to the backing file work from the last cycles. This comes with selftests Cleanups: - Remove a redundant might_sleep() from wait_on_inode() - Initialize pointer with NULL, not 0 - Clarify comment on access_override_creds() - Rework and simplify eventfd_signal() and eventfd_signal_mask() helpers - Process aio completions in batches to avoid needless wakeups - Completely decouple struct mnt_idmap from namespaces. We now only keep the actual idmapping around and don't stash references to namespaces - Reformat maintainer entries to indicate that a given subsystem belongs to fs/ - Simplify fput() for files that were never opened - Get rid of various pointless file helpers - Rename various file helpers - Rename struct file members after SLAB_TYPESAFE_BY_RCU switch from last cycle - Make relatime_need_update() return bool - Use GFP_KERNEL instead of GFP_USER when allocating superblocks - Replace deprecated ida_simple_*() calls with their current ida_*() counterparts Fixes: - Fix comments on user namespace id mapping helpers. They aren't kernel doc comments so they shouldn't be using /** - s/Retuns/Returns/g in various places - Add missing parameter documentation on can_move_mount_beneath() - Rename i_mapping->private_data to i_mapping->i_private_data - Fix a false-positive lockdep warning in pipe_write() for watch queues - Improve __fget_files_rcu() code generation to improve performance - Only notify writer that pipe resizing has finished after setting pipe->max_usage otherwise writers are never notified that the pipe has been resized and hang - Fix some kernel docs in hfsplus - s/passs/pass/g in various places - Fix kernel docs in ntfs - Fix kcalloc() arguments order reported by gcc 14 - Fix uninitialized value in reiserfs" * tag 'vfs-6.8.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (36 commits) reiserfs: fix uninit-value in comp_keys watch_queue: fix kcalloc() arguments order ntfs: dir.c: fix kernel-doc function parameter warnings fs: fix doc comment typo fs tree wide selftests/overlayfs: verify device and inode numbers in /proc/pid/maps fs/proc: show correct device and inode numbers in /proc/pid/maps eventfd: Remove usage of the deprecated ida_simple_xx() API fs: super: use GFP_KERNEL instead of GFP_USER for super block allocation fs/hfsplus: wrapper.c: fix kernel-doc warnings fs: add Jan Kara as reviewer fs/inode: Make relatime_need_update return bool pipe: wakeup wr_wait after setting max_usage file: remove __receive_fd() file: stop exposing receive_fd_user() fs: replace f_rcuhead with f_task_work file: remove pointless wrapper file: s/close_fd_get_file()/file_close_fd()/g Improve __fget_files_rcu() code generation (and thus __fget_light()) file: massage cleanup of files that failed to open fs/pipe: Fix lockdep false-positive in watchqueue pipe_write() ...
KVM: fix direction of dependency on MMU notifiers KVM_GENERIC_MEMORY_ATTRIBUTES requires the generic MMU notifier code, because it uses kvm_mmu_invalidate_begin/end. However, it would not work with a bespoke implementation of MMU notifiers that does not use KVM_GENERIC_MMU_NOTIFIER, because most likely it would not synchronize correctly on invalidation. So the right thing to do is to note the problematic configuration if the architecture does not select itself KVM_GENERIC_MMU_NOTIFIER; not to enable it blindly. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
KVM: introduce CONFIG_KVM_COMMON CONFIG_HAVE_KVM is currently used by some architectures to either enabled the KVM config proper, or to enable host-side code that is not part of the KVM module. However, CONFIG_KVM's "select" statement in virt/kvm/Kconfig corresponds to a third meaning, namely to enable common Kconfigs required by all architectures that support KVM. These three meanings can be replaced respectively by an architecture-specific Kconfig, by IS_ENABLED(CONFIG_KVM), or by a new Kconfig symbol that is in turn selected by the architecture-specific "config KVM". Start by introducing such a new Kconfig symbol, CONFIG_KVM_COMMON. Unlike CONFIG_HAVE_KVM, it is selected by CONFIG_KVM, not by architecture code, and it brings in all dependencies of common KVM code. In particular, INTERVAL_TREE was missing in loongarch and riscv, so that is another thing that is fixed. Fixes: 8132d887a702 ("KVM: remove CONFIG_HAVE_KVM_EVENTFD", 2023-12-08) Reported-by: Randy Dunlap <rdunlap@infradead.org> Closes: https://lore.kernel.org/all/44907c6b-c5bd-4e4a-a921-e4d3825539d8@infradead.org/ Reviewed-by: Andrew Jones <ajones@ventanamicro.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Merge tag 'kvm-riscv-6.8-1' of https://github.com/kvm-riscv/linux into HEAD KVM/riscv changes for 6.8 part #1 - KVM_GET_REG_LIST improvement for vector registers - Generate ISA extension reg_list using macros in get-reg-list selftest - Steal time account support along with selftest
Merge tag 'kvmarm-fixes-6.7-2' of git://git./linux/kernel/git/kvmarm/kvmarm into kvm-master KVM/arm64 fixes for 6.7, part #2 - Ensure a vCPU's redistributor is unregistered from the MMIO bus if vCPU creation fails - Fix building KVM selftests for arm64 from the top-level Makefile
KVM: Convert comment into an assertion in kvm_io_bus_register_dev() Instead of having a comment indicating the need to hold slots_lock when calling kvm_io_bus_register_dev(), make it explicit with a lockdep assertion. Signed-off-by: Marc Zyngier <maz@kernel.org> Link: https://lore.kernel.org/r/20231207151201.3028710-6-maz@kernel.org Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
KVM: remove deprecated UAPIs The deprecated interfaces were removed 15 years ago. KVM's device assignment was deprecated in 4.2 and removed 6.5 years ago; the only interest might be in compiling ancient versions of QEMU, but QEMU has been using its own imported copy of the kernel headers since June 2011. So again we go into archaeology territory; just remove the cruft. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
KVM: remove CONFIG_HAVE_KVM_IRQFD All platforms with a kernel irqchip have support for irqfd. Unify the two configuration items so that userspace can expect to use irqfd to inject interrupts into the irqchip. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
KVM: remove CONFIG_HAVE_KVM_EVENTFD virt/kvm/eventfd.c is compiled unconditionally, meaning that the ioeventfds member of struct kvm is accessed unconditionally. CONFIG_HAVE_KVM_EVENTFD therefore must be defined for KVM common code to compile successfully, remove it. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
KVM: guest-memfd: fix unused-function warning With migration disabled, one function becomes unused: virt/kvm/guest_memfd.c:262:12: error: 'kvm_gmem_migrate_folio' defined but not used [-Werror=unused-function] 262 | static int kvm_gmem_migrate_folio(struct address_space *mapping, | ^~~~~~~~~~~~~~~~~~~~~~ Remove the #ifdef around the reference so that fallback_migrate_folio() is never used. The gmem implementation of the hook is trivial; since the gmem mapping is unmovable, the pages should not be migrated anyway. Fixes: a7800aa80ea4 ("KVM: Add KVM_CREATE_GUEST_MEMFD ioctl() for guest-specific backing memory") Reported-by: Arnd Bergmann <arnd@arndb.de> Suggested-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Revert "KVM: Prevent module exit until all VMs are freed" Revert KVM's misguided attempt to "fix" a use-after-module-unload bug that was actually due to failure to flush a workqueue, not a lack of module refcounting. Pinning the KVM module until kvm_vm_destroy() doesn't prevent use-after-free due to the module being unloaded, as userspace can invoke delete_module() the instant the last reference to KVM is put, i.e. can cause all KVM code to be unmapped while KVM is actively executing said code. Generally speaking, the many instances of module_put(THIS_MODULE) notwithstanding, outside of a few special paths, a module can never safely put the last reference to itself without creating deadlock, i.e. something external to the module *must* put the last reference. In other words, having VMs grab a reference to the KVM module is futile, pointless, and as evidenced by the now-reverted commit 70375c2d8fa3 ("Revert "KVM: set owner of cpu and vm file operations""), actively dangerous. This reverts commit 405294f29faee5de8c10cb9d4a90e229c2835279 and commit 5f6de5cbebee925a612856fce6f9182bb3eee0db. Fixes: 405294f29fae ("KVM: Unconditionally get a ref to /dev/kvm module when creating a VM") Fixes: 5f6de5cbebee ("KVM: Prevent module exit until all VMs are freed") Link: https://lore.kernel.org/r/20231018204624.1905300-4-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc@google.com>
KVM: Set file_operations.owner appropriately for all such structures Set .owner for all KVM-owned filed types so that the KVM module is pinned until any files with callbacks back into KVM are completely freed. Using "struct kvm" as a proxy for the module, i.e. keeping KVM-the-module alive while there are active VMs, doesn't provide full protection. Userspace can invoke delete_module() the instant the last reference to KVM is put. If KVM itself puts the last reference, e.g. via kvm_destroy_vm(), then it's possible for KVM to be preempted and deleted/unloaded before KVM fully exits, e.g. when the task running kvm_destroy_vm() is scheduled back in, it will jump to a code page that is no longer mapped. Note, file types that can call into sub-module code, e.g. kvm-intel.ko or kvm-amd.ko on x86, must use the module pointer passed to kvm_init(), not THIS_MODULE (which points at kvm.ko). KVM assumes that if /dev/kvm is reachable, e.g. VMs are active, then the vendor module is loaded. To reduce the probability of forgetting to set .owner entirely, use THIS_MODULE for stats files where KVM does not call back into vendor code. This reverts commit 70375c2d8fa3fb9b0b59207a9c5df1e2e1205c10, and fixes several other file types that have been buggy since their introduction. Fixes: 70375c2d8fa3 ("Revert "KVM: set owner of cpu and vm file operations"") Fixes: 3bcd0662d66f ("KVM: X86: Introduce mmu_rmaps_stat per-vm debugfs file") Reported-by: Al Viro <viro@zeniv.linux.org.uk> Link: https://lore.kernel.org/all/20231010003746.GN800259@ZenIV Link: https://lore.kernel.org/r/20231018204624.1905300-2-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc@google.com>
KVM: Harden copying of userspace-array against overflow kvm_main.c utilizes vmemdup_user() and array_size() to copy a userspace array. Currently, this does not check for an overflow. Use the new wrapper vmemdup_array_user() to copy the array more safely. Note, KVM explicitly checks the number of entries before duplicating the array, i.e. adding the overflow check should be a glorified nop. Suggested-by: Dave Airlie <airlied@redhat.com> Signed-off-by: Philipp Stanner <pstanner@redhat.com> Link: https://lore.kernel.org/r/20231102181526.43279-4-pstanner@redhat.com [sean: call out that KVM pre-checks the number of entries] Signed-off-by: Sean Christopherson <seanjc@google.com>
KVM: move KVM_CAP_DEVICE_CTRL to the generic check KVM_CAP_DEVICE_CTRL allows userspace to check if the kvm_device framework (e.g. KVM_CREATE_DEVICE) is supported by KVM. Move KVM_CAP_DEVICE_CTRL to the generic check for the two reasons: 1) it already supports arch agnostic usages (i.e. KVM_DEV_TYPE_VFIO). For example, userspace VFIO implementation may needs to create KVM_DEV_TYPE_VFIO on x86, riscv, or arm etc. It is simpler to have it checked at the generic code than at each arch's code. 2) KVM_CREATE_DEVICE has been added to the generic code. Link: https://lore.kernel.org/all/20221215115207.14784-1-wei.w.wang@intel.com Signed-off-by: Wei Wang <wei.w.wang@intel.com> Reviewed-by: Sean Christopherson <seanjc@google.com> Acked-by: Anup Patel <anup@brainfault.org> (riscv) Reviewed-by: Oliver Upton <oliver.upton@linux.dev> Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) Link: https://lore.kernel.org/r/20230315101606.10636-1-wei.w.wang@intel.com Signed-off-by: Sean Christopherson <seanjc@google.com>
eventfd: simplify eventfd_signal() Ever since the eventfd type was introduced back in 2007 in commit e1ad7468c77d ("signal/timer/event: eventfd core") the eventfd_signal() function only ever passed 1 as a value for @n. There's no point in keeping that additional argument. Link: https://lore.kernel.org/r/20231122-vfs-eventfd-signal-v2-2-bd549b14ce0c@kernel.org Acked-by: Xu Yilun <yilun.xu@intel.com> Acked-by: Andrew Donnellan <ajd@linux.ibm.com> # ocxl Acked-by: Eric Farman <farman@linux.ibm.com> # s390 Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Christian Brauner <brauner@kernel.org>