5c73b9a2b1
A sequence counter write side critical section must be protected by some form of locking to serialize writers. A plain seqcount_t does not contain the information of which lock must be held when entering a write side critical section. Use the new seqcount_spinlock_t data type, which allows to associate a spinlock with the sequence counter. This enables lockdep to verify that the spinlock used for writer serialization is held when the write side critical section is entered. If lockdep is disabled this lock association is compiled out and has neither storage size nor runtime overhead. Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Link: https://lkml.kernel.org/r/20200720155530.1173732-24-a.darwish@linutronix.de
65 lines
2 KiB
C
65 lines
2 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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*
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* irqfd: Allows an fd to be used to inject an interrupt to the guest
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* Credit goes to Avi Kivity for the original idea.
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*/
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#ifndef __LINUX_KVM_IRQFD_H
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#define __LINUX_KVM_IRQFD_H
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#include <linux/kvm_host.h>
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#include <linux/poll.h>
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/*
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* Resampling irqfds are a special variety of irqfds used to emulate
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* level triggered interrupts. The interrupt is asserted on eventfd
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* trigger. On acknowledgment through the irq ack notifier, the
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* interrupt is de-asserted and userspace is notified through the
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* resamplefd. All resamplers on the same gsi are de-asserted
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* together, so we don't need to track the state of each individual
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* user. We can also therefore share the same irq source ID.
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*/
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struct kvm_kernel_irqfd_resampler {
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struct kvm *kvm;
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/*
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* List of resampling struct _irqfd objects sharing this gsi.
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* RCU list modified under kvm->irqfds.resampler_lock
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*/
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struct list_head list;
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struct kvm_irq_ack_notifier notifier;
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/*
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* Entry in list of kvm->irqfd.resampler_list. Use for sharing
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* resamplers among irqfds on the same gsi.
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* Accessed and modified under kvm->irqfds.resampler_lock
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*/
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struct list_head link;
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};
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struct kvm_kernel_irqfd {
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/* Used for MSI fast-path */
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struct kvm *kvm;
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wait_queue_entry_t wait;
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/* Update side is protected by irqfds.lock */
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struct kvm_kernel_irq_routing_entry irq_entry;
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seqcount_spinlock_t irq_entry_sc;
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/* Used for level IRQ fast-path */
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int gsi;
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struct work_struct inject;
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/* The resampler used by this irqfd (resampler-only) */
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struct kvm_kernel_irqfd_resampler *resampler;
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/* Eventfd notified on resample (resampler-only) */
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struct eventfd_ctx *resamplefd;
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/* Entry in list of irqfds for a resampler (resampler-only) */
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struct list_head resampler_link;
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/* Used for setup/shutdown */
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struct eventfd_ctx *eventfd;
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struct list_head list;
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poll_table pt;
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struct work_struct shutdown;
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struct irq_bypass_consumer consumer;
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struct irq_bypass_producer *producer;
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};
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#endif /* __LINUX_KVM_IRQFD_H */
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