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-rw-r--r--Documentation/virt/kvm/api.rst5
1 files changed, 5 insertions, 0 deletions
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 6fb1870f0999..1bd2d42e6424 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -8001,6 +8001,11 @@ apply some other policy-based mitigation. When exiting to userspace, KVM sets
KVM_RUN_X86_BUS_LOCK in vcpu-run->flags, and conditionally sets the exit_reason
to KVM_EXIT_X86_BUS_LOCK.
+Due to differences in the underlying hardware implementation, the vCPU's RIP at
+the time of exit diverges between Intel and AMD. On Intel hosts, RIP points at
+the next instruction, i.e. the exit is trap-like. On AMD hosts, RIP points at
+the offending instruction, i.e. the exit is fault-like.
+
Note! Detected bus locks may be coincident with other exits to userspace, i.e.
KVM_RUN_X86_BUS_LOCK should be checked regardless of the primary exit reason if
userspace wants to take action on all detected bus locks.