mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson
synced 2025-08-27 06:50:37 +00:00
530a8ba71b
Cap the number of ring entries that are reset in a single ioctl to INT_MAX
to ensure userspace isn't confused by a wrap into negative space, and so
that, in a truly pathological scenario, KVM doesn't miss a TLB flush due
to the count wrapping to zero. While the size of the ring is fixed at
0x10000 entries and KVM (currently) supports at most 4096, userspace is
allowed to harvest entries from the ring while the reset is in-progress,
i.e. it's possible for the ring to always have harvested entries.
Opportunistically return an actual error code from the helper so that a
future fix to handle pending signals can gracefully return -EINTR. Drop
the function comment now that the return code is a stanard 0/-errno (and
because a future commit will add a proper lockdep assertion).
Opportunistically drop a similarly stale comment for kvm_dirty_ring_push().
Cc: Peter Xu <peterx@redhat.com>
Cc: Yan Zhao <yan.y.zhao@intel.com>
Cc: Maxim Levitsky <mlevitsk@redhat.com>
Cc: Binbin Wu <binbin.wu@linux.intel.com>
Fixes: fb04a1eddb ("KVM: X86: Implement ring-based dirty memory tracking")
Reviewed-by: James Houghton <jthoughton@google.com>
Reviewed-by: Binbin Wu <binbin.wu@linux.intel.com>
Reviewed-by: Yan Zhao <yan.y.zhao@intel.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/20250516213540.2546077-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
95 lines
2.6 KiB
C
95 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(struct kvm *kvm)
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{
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return 0;
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}
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static inline bool kvm_use_dirty_bitmap(struct kvm *kvm)
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{
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return true;
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}
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static inline int kvm_dirty_ring_alloc(struct kvm *kvm, 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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int *nr_entries_reset)
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{
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return -ENOENT;
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}
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static inline void kvm_dirty_ring_push(struct kvm_vcpu *vcpu,
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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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#else /* CONFIG_HAVE_KVM_DIRTY_RING */
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int kvm_cpu_dirty_log_size(struct kvm *kvm);
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bool kvm_use_dirty_bitmap(struct kvm *kvm);
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bool kvm_arch_allow_write_without_running_vcpu(struct kvm *kvm);
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u32 kvm_dirty_ring_get_rsvd_entries(struct kvm *kvm);
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int kvm_dirty_ring_alloc(struct kvm *kvm, struct kvm_dirty_ring *ring,
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int index, u32 size);
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int kvm_dirty_ring_reset(struct kvm *kvm, struct kvm_dirty_ring *ring,
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int *nr_entries_reset);
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void kvm_dirty_ring_push(struct kvm_vcpu *vcpu, u32 slot, u64 offset);
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bool kvm_dirty_ring_check_request(struct kvm_vcpu *vcpu);
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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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#endif /* CONFIG_HAVE_KVM_DIRTY_RING */
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#endif /* KVM_DIRTY_RING_H */
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