David Woodhouse 310bc39546 KVM: x86/xen: Avoid deadlock by adding kvm->arch.xen.xen_lock leaf node lock ... In commit 14243b3871 ("KVM: x86/xen: Add KVM_IRQ_ROUTING_XEN_EVTCHN and event channel delivery") the clever version of me left some helpful notes for those who would come after him: /* * For the irqfd workqueue, using the main kvm->lock mutex is * fine since this function is invoked from kvm_set_irq() with * no other lock held, no srcu. In future if it will be called * directly from a vCPU thread (e.g. on hypercall for an IPI) * then it may need to switch to using a leaf-node mutex for * serializing the shared_info mapping. */ mutex_lock(&kvm->lock); In commit 2fd6df2f2b ("KVM: x86/xen: intercept EVTCHNOP_send from guests") the other version of me ran straight past that comment without reading it, and introduced a potential deadlock by taking vcpu->mutex and kvm->lock in the wrong order. Solve this as originally suggested, by adding a leaf-node lock in the Xen state rather than using kvm->lock for it. Fixes: 2fd6df2f2b ("KVM: x86/xen: intercept EVTCHNOP_send from guests") Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Message-Id: <20230111180651.14394-4-dwmw2@infradead.org> [Rebase, add docs. - Paolo] Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>		2023-01-11 17:45:58 -05:00
..
arm	KVM: arm64: Fix pvtime documentation	2022-11-11 16:29:22 +00:00
devices	KVM/arm64 updates for 6.2	2022-12-09 09:12:12 +01:00
s390	ARM:	2022-08-04 14:59:54 -07:00
x86	KVM: Move halt-polling documentation into common directory	2022-12-02 13:20:30 -05:00
api.rst	KVM/arm64 fixes for 6.2, take #1	2023-01-11 13:31:53 -05:00
halt-polling.rst	KVM: Document the interaction between KVM_CAP_HALT_POLL and halt_poll_ns	2022-12-02 13:20:30 -05:00
index.rst	KVM: Move halt-polling documentation into common directory	2022-12-02 13:20:30 -05:00
locking.rst	KVM: x86/xen: Avoid deadlock by adding kvm->arch.xen.xen_lock leaf node lock	2023-01-11 17:45:58 -05:00
ppc-pv.rst	docs: kvm: Convert ppc-pv.txt to ReST format	2020-02-12 20:10:05 +01:00
review-checklist.rst	docs: fix broken references for ReST files that moved around	2020-04-20 15:45:03 -06:00
vcpu-requests.rst	KVM: remove KVM_REQ_UNHALT	2022-09-26 12:37:21 -04:00