mirror of https://github.com/proxmox/mirror_qemu
KVM: Disable manual dirty log when dirty ring enabled
KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 is for KVM_CLEAR_DIRTY_LOG, which is only useful for KVM_GET_DIRTY_LOG. Skip enabling it for kvm dirty ring. More importantly, KVM_DIRTY_LOG_INITIALLY_SET will not wr-protect all the pages initially, which is against how kvm dirty ring is used - there's no way for kvm dirty ring to re-protect a page before it's notified as being written first with a GFN entry in the ring! So when KVM_DIRTY_LOG_INITIALLY_SET is enabled with dirty ring, we'll see silent data loss after migration. Signed-off-by: Peter Xu <peterx@redhat.com> Message-Id: <20210506160549.130416-10-peterx@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>master
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2ea5cb0a47
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a81a592698
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@ -2131,6 +2131,14 @@ static int kvm_init(MachineState *ms)
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s->coalesced_pio = s->coalesced_mmio &&
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s->coalesced_pio = s->coalesced_mmio &&
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kvm_check_extension(s, KVM_CAP_COALESCED_PIO);
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kvm_check_extension(s, KVM_CAP_COALESCED_PIO);
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/*
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* KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 is not needed when dirty ring is
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* enabled. More importantly, KVM_DIRTY_LOG_INITIALLY_SET will assume no
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* page is wr-protected initially, which is against how kvm dirty ring is
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* usage - kvm dirty ring requires all pages are wr-protected at the very
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* beginning. Enabling this feature for dirty ring causes data corruption.
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*/
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if (!s->kvm_dirty_ring_size) {
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dirty_log_manual_caps =
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dirty_log_manual_caps =
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kvm_check_extension(s, KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2);
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kvm_check_extension(s, KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2);
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dirty_log_manual_caps &= (KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE |
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dirty_log_manual_caps &= (KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE |
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@ -2147,6 +2155,7 @@ static int kvm_init(MachineState *ms)
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s->manual_dirty_log_protect = 0;
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s->manual_dirty_log_protect = 0;
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}
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}
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}
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}
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}
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#ifdef KVM_CAP_VCPU_EVENTS
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#ifdef KVM_CAP_VCPU_EVENTS
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s->vcpu_events = kvm_check_extension(s, KVM_CAP_VCPU_EVENTS);
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s->vcpu_events = kvm_check_extension(s, KVM_CAP_VCPU_EVENTS);
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