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2efd61a608
The various kvm_write_guest() and mark_page_dirty() functions must only ever be called in the context of an active vCPU, because if dirty ring tracking is enabled it may simply oops when kvm_get_running_vcpu() returns NULL for the vcpu and then kvm_dirty_ring_get() dereferences it. This oops was reported by "butt3rflyh4ck" <butterflyhuangxx@gmail.com> in https://lore.kernel.org/kvm/CAFcO6XOmoS7EacN_n6v4Txk7xL7iqRa2gABg3F7E3Naf5uG94g@mail.gmail.com/ That actual bug will be fixed under separate cover but this warning should help to prevent new ones from being added. Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Message-Id: <20211210163625.2886-2-dwmw2@infradead.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
97 lines
2.6 KiB
C
97 lines
2.6 KiB
C
#ifndef KVM_DIRTY_RING_H
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#define KVM_DIRTY_RING_H
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#include <linux/kvm.h>
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/**
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* kvm_dirty_ring: KVM internal dirty ring structure
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*
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* @dirty_index: free running counter that points to the next slot in
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* dirty_ring->dirty_gfns, where a new dirty page should go
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* @reset_index: free running counter that points to the next dirty page
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* in dirty_ring->dirty_gfns for which dirty trap needs to
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* be reenabled
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* @size: size of the compact list, dirty_ring->dirty_gfns
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* @soft_limit: when the number of dirty pages in the list reaches this
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* limit, vcpu that owns this ring should exit to userspace
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* to allow userspace to harvest all the dirty pages
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* @dirty_gfns: the array to keep the dirty gfns
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* @index: index of this dirty ring
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*/
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struct kvm_dirty_ring {
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u32 dirty_index;
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u32 reset_index;
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u32 size;
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u32 soft_limit;
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struct kvm_dirty_gfn *dirty_gfns;
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int index;
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};
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#ifndef CONFIG_HAVE_KVM_DIRTY_RING
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/*
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* If CONFIG_HAVE_HVM_DIRTY_RING not defined, kvm_dirty_ring.o should
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* not be included as well, so define these nop functions for the arch.
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*/
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static inline u32 kvm_dirty_ring_get_rsvd_entries(void)
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{
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return 0;
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}
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static inline int kvm_dirty_ring_alloc(struct kvm_dirty_ring *ring,
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int index, u32 size)
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{
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return 0;
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}
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static inline int kvm_dirty_ring_reset(struct kvm *kvm,
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struct kvm_dirty_ring *ring)
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{
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return 0;
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}
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static inline void kvm_dirty_ring_push(struct kvm_dirty_ring *ring,
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u32 slot, u64 offset)
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{
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}
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static inline struct page *kvm_dirty_ring_get_page(struct kvm_dirty_ring *ring,
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u32 offset)
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{
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return NULL;
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}
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static inline void kvm_dirty_ring_free(struct kvm_dirty_ring *ring)
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{
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}
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static inline bool kvm_dirty_ring_soft_full(struct kvm_dirty_ring *ring)
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{
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return true;
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}
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#else /* CONFIG_HAVE_KVM_DIRTY_RING */
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u32 kvm_dirty_ring_get_rsvd_entries(void);
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int kvm_dirty_ring_alloc(struct kvm_dirty_ring *ring, int index, u32 size);
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/*
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* called with kvm->slots_lock held, returns the number of
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* processed pages.
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*/
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int kvm_dirty_ring_reset(struct kvm *kvm, struct kvm_dirty_ring *ring);
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/*
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* returns =0: successfully pushed
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* <0: unable to push, need to wait
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*/
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void kvm_dirty_ring_push(struct kvm_dirty_ring *ring, u32 slot, u64 offset);
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/* for use in vm_operations_struct */
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struct page *kvm_dirty_ring_get_page(struct kvm_dirty_ring *ring, u32 offset);
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void kvm_dirty_ring_free(struct kvm_dirty_ring *ring);
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bool kvm_dirty_ring_soft_full(struct kvm_dirty_ring *ring);
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#endif /* CONFIG_HAVE_KVM_DIRTY_RING */
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#endif /* KVM_DIRTY_RING_H */
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