wireguard-linux/virt/kvm/eventfd.c, branch update-toolchain

KVM: eventfd: Use synchronize_srcu_expedited() on shutdown

2024-08-13T16:09:35Z

When hot-unplug a device which has many queues, and guest CPU will has huge jitter, and unplugging is very slow. It turns out synchronize_srcu() in irqfd_shutdown() caused the guest jitter and unplugging latency, so replace synchronize_srcu() with synchronize_srcu_expedited(), to accelerate the unplugging, and reduce the guest OS jitter, this accelerates the VM reboot too. Signed-off-by: Li RongQing Message-ID: <20240711121130.38917-1-lirongqing@baidu.com> [Call it just once in irqfd_resampler_shutdown. - Paolo] Signed-off-by: Paolo Bonzini

Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

2024-01-17T21:03:37Z

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() ...

KVM: clean up directives to compile out irqfds

2023-12-08T20:43:34Z

Keep all #ifdef CONFIG_HAVE_KVM_IRQCHIP parts of eventfd.c together, and compile out the irqfds field of struct kvm if the symbol is not defined. Signed-off-by: Paolo Bonzini

KVM: remove CONFIG_HAVE_KVM_IRQFD

2023-12-08T20:43:33Z

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

eventfd: simplify eventfd_signal()

2023-11-28T13:08:38Z

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 Acked-by: Andrew Donnellan # ocxl Acked-by: Eric Farman # s390 Reviewed-by: Jan Kara Reviewed-by: Jens Axboe Signed-off-by: Christian Brauner

kvm/eventfd: use list_for_each_entry when deassign ioeventfd

2023-06-13T21:25:39Z

Simpify kvm_deassign_ioeventfd_idx to use list_for_each_entry as the loop just ends at the entry that's found and deleted. Note, coalesced_mmio_ops and ioeventfd_ops are the only instances of kvm_io_device_ops that implement a destructor, all other callers of kvm_io_bus_unregister_dev() are unaffected by this change. Suggested-by: Michal Luczaj Signed-off-by: Wei Wang Reviewed-by: Sean Christopherson Link: https://lore.kernel.org/r/20230207123713.3905-3-wei.w.wang@intel.com [sean: call out that only select users implement a destructor] Signed-off-by: Sean Christopherson

KVM: destruct kvm_io_device while unregistering it from kvm_io_bus

2023-06-13T21:18:09Z

Current usage of kvm_io_device requires users to destruct it with an extra call of kvm_iodevice_destructor after the device gets unregistered from kvm_io_bus. This is not necessary and can cause errors if a user forgot to make the extra call. Simplify the usage by combining kvm_iodevice_destructor into kvm_io_bus_unregister_dev. This reduces LOCs a bit for users and can avoid the leakage of destructing the device explicitly. Signed-off-by: Wei Wang Reviewed-by: Sean Christopherson Link: https://lore.kernel.org/r/20230207123713.3905-2-wei.w.wang@intel.com Signed-off-by: Sean Christopherson

KVM: Don't kfree(NULL) on kzalloc() failure in kvm_assign_ioeventfd_idx()

2023-06-01T20:48:54Z

On kzalloc() failure, taking the `goto fail` path leads to kfree(NULL). Such no-op has no use. Move it out. Signed-off-by: Michal Luczaj Reviewed-by: Sean Christopherson Reviewed-by: Philippe Mathieu-Daudé Link: https://lore.kernel.org/r/20230327175457.735903-1-mhal@rbox.co Signed-off-by: Sean Christopherson

KVM: x86/ioapic: Resample the pending state of an IRQ when unmasking

2023-03-27T14:13:28Z

KVM irqfd based emulation of level-triggered interrupts doesn't work quite correctly in some cases, particularly in the case of interrupts that are handled in a Linux guest as oneshot interrupts (IRQF_ONESHOT). Such an interrupt is acked to the device in its threaded irq handler, i.e. later than it is acked to the interrupt controller (EOI at the end of hardirq), not earlier. Linux keeps such interrupt masked until its threaded handler finishes, to prevent the EOI from re-asserting an unacknowledged interrupt. However, with KVM + vfio (or whatever is listening on the resamplefd) we always notify resamplefd at the EOI, so vfio prematurely unmasks the host physical IRQ, thus a new physical interrupt is fired in the host. This extra interrupt in the host is not a problem per se. The problem is that it is unconditionally queued for injection into the guest, so the guest sees an extra bogus interrupt. [*] There are observed at least 2 user-visible issues caused by those extra erroneous interrupts for a oneshot irq in the guest: 1. System suspend aborted due to a pending wakeup interrupt from ChromeOS EC (drivers/platform/chrome/cros_ec.c). 2. Annoying "invalid report id data" errors from ELAN0000 touchpad (drivers/input/mouse/elan_i2c_core.c), flooding the guest dmesg every time the touchpad is touched. The core issue here is that by the time when the guest unmasks the IRQ, the physical IRQ line is no longer asserted (since the guest has acked the interrupt to the device in the meantime), yet we unconditionally inject the interrupt queued into the guest by the previous resampling. So to fix the issue, we need a way to detect that the IRQ is no longer pending, and cancel the queued interrupt in this case. With IOAPIC we are not able to probe the physical IRQ line state directly (at least not if the underlying physical interrupt controller is an IOAPIC too), so in this patch we use irqfd resampler for that. Namely, instead of injecting the queued interrupt, we just notify the resampler that this interrupt is done. If the IRQ line is actually already deasserted, we are done. If it is still asserted, a new interrupt will be shortly triggered through irqfd and injected into the guest. In the case if there is no irqfd resampler registered for this IRQ, we cannot fix the issue, so we keep the existing behavior: immediately unconditionally inject the queued interrupt. This patch fixes the issue for x86 IOAPIC only. In the long run, we can fix it for other irqchips and other architectures too, possibly taking advantage of reading the physical state of the IRQ line, which is possible with some other irqchips (e.g. with arm64 GIC, maybe even with the legacy x86 PIC). [*] In this description we assume that the interrupt is a physical host interrupt forwarded to the guest e.g. by vfio. Potentially the same issue may occur also with a purely virtual interrupt from an emulated device, e.g. if the guest handles this interrupt, again, as a oneshot interrupt. Signed-off-by: Dmytro Maluka Link: https://lore.kernel.org/kvm/31420943-8c5f-125c-a5ee-d2fde2700083@semihalf.com/ Link: https://lore.kernel.org/lkml/87o7wrug0w.wl-maz@kernel.org/ Message-Id: <20230322204344.50138-3-dmy@semihalf.com> Signed-off-by: Paolo Bonzini

KVM: irqfd: Make resampler_list an RCU list

2023-03-27T14:13:28Z

It is useful to be able to do read-only traversal of the list of all the registered irqfd resamplers without locking the resampler_lock mutex. In particular, we are going to traverse it to search for a resampler registered for the given irq of an irqchip, and that will be done with an irqchip spinlock (ioapic->lock) held, so it is undesirable to lock a mutex in this context. So turn this list into an RCU list. For protecting the read side, reuse kvm->irq_srcu which is already used for protecting a number of irq related things (kvm->irq_routing, irqfd->resampler->list, kvm->irq_ack_notifier_list, kvm->arch.mask_notifier_list). Signed-off-by: Dmytro Maluka Message-Id: <20230322204344.50138-2-dmy@semihalf.com> Signed-off-by: Paolo Bonzini