KVM: PPC: Book3S HV: Drop locks around call to kvmppc_pin_guest_page
At the moment we call kvmppc_pin_guest_page() in kvmppc_update_vpa()
with two spinlocks held: the vcore lock and the vcpu->vpa_update_lock.
This is not good, since kvmppc_pin_guest_page() calls down_read() and
get_user_pages_fast(), both of which can sleep. This bug was introduced
in 2e25aa5f
("KVM: PPC: Book3S HV: Make virtual processor area
registration more robust").
This arranges to drop those spinlocks before calling
kvmppc_pin_guest_page() and re-take them afterwards. Dropping the
vcore lock in kvmppc_run_core() means we have to set the vcore_state
field to VCORE_RUNNING before we drop the lock, so that other vcpus
won't try to run this vcore.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Acked-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
parent
f961f72836
commit
081f323bd3
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@ -268,24 +268,45 @@ static unsigned long do_h_register_vpa(struct kvm_vcpu *vcpu,
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return err;
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return err;
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}
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}
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static void kvmppc_update_vpa(struct kvm *kvm, struct kvmppc_vpa *vpap)
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static void kvmppc_update_vpa(struct kvm_vcpu *vcpu, struct kvmppc_vpa *vpap)
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{
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{
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struct kvm *kvm = vcpu->kvm;
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void *va;
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void *va;
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unsigned long nb;
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unsigned long nb;
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unsigned long gpa;
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/*
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* We need to pin the page pointed to by vpap->next_gpa,
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* but we can't call kvmppc_pin_guest_page under the lock
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* as it does get_user_pages() and down_read(). So we
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* have to drop the lock, pin the page, then get the lock
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* again and check that a new area didn't get registered
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* in the meantime.
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*/
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for (;;) {
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gpa = vpap->next_gpa;
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spin_unlock(&vcpu->arch.vpa_update_lock);
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va = NULL;
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nb = 0;
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if (gpa)
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va = kvmppc_pin_guest_page(kvm, vpap->next_gpa, &nb);
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spin_lock(&vcpu->arch.vpa_update_lock);
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if (gpa == vpap->next_gpa)
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break;
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/* sigh... unpin that one and try again */
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if (va)
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kvmppc_unpin_guest_page(kvm, va);
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}
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vpap->update_pending = 0;
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vpap->update_pending = 0;
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va = NULL;
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if (va && nb < vpap->len) {
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if (vpap->next_gpa) {
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/*
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va = kvmppc_pin_guest_page(kvm, vpap->next_gpa, &nb);
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* If it's now too short, it must be that userspace
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if (nb < vpap->len) {
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* has changed the mappings underlying guest memory,
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/*
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* so unregister the region.
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* If it's now too short, it must be that userspace
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*/
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* has changed the mappings underlying guest memory,
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kvmppc_unpin_guest_page(kvm, va);
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* so unregister the region.
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va = NULL;
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*/
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kvmppc_unpin_guest_page(kvm, va);
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va = NULL;
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}
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}
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}
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if (vpap->pinned_addr)
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if (vpap->pinned_addr)
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kvmppc_unpin_guest_page(kvm, vpap->pinned_addr);
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kvmppc_unpin_guest_page(kvm, vpap->pinned_addr);
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@ -296,20 +317,18 @@ static void kvmppc_update_vpa(struct kvm *kvm, struct kvmppc_vpa *vpap)
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static void kvmppc_update_vpas(struct kvm_vcpu *vcpu)
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static void kvmppc_update_vpas(struct kvm_vcpu *vcpu)
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{
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{
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struct kvm *kvm = vcpu->kvm;
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spin_lock(&vcpu->arch.vpa_update_lock);
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spin_lock(&vcpu->arch.vpa_update_lock);
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if (vcpu->arch.vpa.update_pending) {
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if (vcpu->arch.vpa.update_pending) {
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kvmppc_update_vpa(kvm, &vcpu->arch.vpa);
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kvmppc_update_vpa(vcpu, &vcpu->arch.vpa);
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init_vpa(vcpu, vcpu->arch.vpa.pinned_addr);
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init_vpa(vcpu, vcpu->arch.vpa.pinned_addr);
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}
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}
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if (vcpu->arch.dtl.update_pending) {
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if (vcpu->arch.dtl.update_pending) {
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kvmppc_update_vpa(kvm, &vcpu->arch.dtl);
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kvmppc_update_vpa(vcpu, &vcpu->arch.dtl);
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vcpu->arch.dtl_ptr = vcpu->arch.dtl.pinned_addr;
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vcpu->arch.dtl_ptr = vcpu->arch.dtl.pinned_addr;
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vcpu->arch.dtl_index = 0;
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vcpu->arch.dtl_index = 0;
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}
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}
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if (vcpu->arch.slb_shadow.update_pending)
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if (vcpu->arch.slb_shadow.update_pending)
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kvmppc_update_vpa(kvm, &vcpu->arch.slb_shadow);
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kvmppc_update_vpa(vcpu, &vcpu->arch.slb_shadow);
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spin_unlock(&vcpu->arch.vpa_update_lock);
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spin_unlock(&vcpu->arch.vpa_update_lock);
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}
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}
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@ -800,12 +819,39 @@ static int kvmppc_run_core(struct kvmppc_vcore *vc)
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struct kvm_vcpu *vcpu, *vcpu0, *vnext;
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struct kvm_vcpu *vcpu, *vcpu0, *vnext;
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long ret;
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long ret;
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u64 now;
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u64 now;
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int ptid, i;
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int ptid, i, need_vpa_update;
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/* don't start if any threads have a signal pending */
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/* don't start if any threads have a signal pending */
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list_for_each_entry(vcpu, &vc->runnable_threads, arch.run_list)
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need_vpa_update = 0;
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list_for_each_entry(vcpu, &vc->runnable_threads, arch.run_list) {
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if (signal_pending(vcpu->arch.run_task))
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if (signal_pending(vcpu->arch.run_task))
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return 0;
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return 0;
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need_vpa_update |= vcpu->arch.vpa.update_pending |
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vcpu->arch.slb_shadow.update_pending |
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vcpu->arch.dtl.update_pending;
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}
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/*
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* Initialize *vc, in particular vc->vcore_state, so we can
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* drop the vcore lock if necessary.
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*/
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vc->n_woken = 0;
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vc->nap_count = 0;
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vc->entry_exit_count = 0;
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vc->vcore_state = VCORE_RUNNING;
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vc->in_guest = 0;
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vc->napping_threads = 0;
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/*
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* Updating any of the vpas requires calling kvmppc_pin_guest_page,
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* which can't be called with any spinlocks held.
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*/
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if (need_vpa_update) {
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spin_unlock(&vc->lock);
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list_for_each_entry(vcpu, &vc->runnable_threads, arch.run_list)
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kvmppc_update_vpas(vcpu);
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spin_lock(&vc->lock);
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}
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/*
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/*
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* Make sure we are running on thread 0, and that
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* Make sure we are running on thread 0, and that
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@ -838,20 +884,10 @@ static int kvmppc_run_core(struct kvmppc_vcore *vc)
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if (vcpu->arch.ceded)
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if (vcpu->arch.ceded)
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vcpu->arch.ptid = ptid++;
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vcpu->arch.ptid = ptid++;
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vc->n_woken = 0;
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vc->nap_count = 0;
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vc->entry_exit_count = 0;
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vc->vcore_state = VCORE_RUNNING;
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vc->stolen_tb += mftb() - vc->preempt_tb;
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vc->stolen_tb += mftb() - vc->preempt_tb;
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vc->in_guest = 0;
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vc->pcpu = smp_processor_id();
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vc->pcpu = smp_processor_id();
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vc->napping_threads = 0;
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list_for_each_entry(vcpu, &vc->runnable_threads, arch.run_list) {
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list_for_each_entry(vcpu, &vc->runnable_threads, arch.run_list) {
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kvmppc_start_thread(vcpu);
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kvmppc_start_thread(vcpu);
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if (vcpu->arch.vpa.update_pending ||
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vcpu->arch.slb_shadow.update_pending ||
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vcpu->arch.dtl.update_pending)
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kvmppc_update_vpas(vcpu);
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kvmppc_create_dtl_entry(vcpu, vc);
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kvmppc_create_dtl_entry(vcpu, vc);
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}
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}
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/* Grab any remaining hw threads so they can't go into the kernel */
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/* Grab any remaining hw threads so they can't go into the kernel */
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