mirror of https://github.com/xemu-project/xemu.git
bceeeef9e7
If userspace (QEMU) debug guest, when #DB is raised in guest and intercepted by KVM, KVM forwards information on #DB to userspace instead of injecting #DB to guest. While doing so, KVM don't update vCPU DR6 but instead report the #DB DR6 value to userspace for further handling. See KVM's handle_exception() DB_VECTOR handler. QEMU handler for this case is kvm_handle_debug(). This handler basically checks if #DB is related to one of user set hardware breakpoints and if not, it re-inject #DB into guest. The re-injection is done by setting env->exception_injected to #DB which will later be passed as events.exception.nr to KVM_SET_VCPU_EVENTS ioctl by kvm_put_vcpu_events(). However, in case userspace re-injects #DB, KVM expects userspace to set vCPU DR6 as reported to userspace when #DB was intercepted! Otherwise, KVM_REQ_EVENT handler will inject #DB with wrong DR6 to guest. Fix this issue by updating vCPU DR6 appropriately when re-inject #DB to guest. Reviewed-by: Nikita Leshenko <nikita.leshchenko@oracle.com> Reviewed-by: Krish Sadhukhan <krish.sadhukhan@oracle.com> Signed-off-by: Liran Alon <liran.alon@oracle.com> Message-Id: <20190619162140.133674-5-liran.alon@oracle.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> |
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