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authorOliver Upton2020-02-07 02:36:06 -0800
committerPaolo Bonzini2020-02-12 12:34:10 +0100
commita06230b62b898e51cfb1de256b2042a09a691f58 (patch)
tree0e93155a12a1ab62d71ec6a3dad55576bc621ddb /tools
parent684c0422da71da0cd81319c90b8099b563b13da4 (diff)
KVM: x86: Deliver exception payload on KVM_GET_VCPU_EVENTS
KVM allows the deferral of exception payloads when a vCPU is in guest mode to allow the L1 hypervisor to intercept certain events (#PF, #DB) before register state has been modified. However, this behavior is incompatible with the KVM_{GET,SET}_VCPU_EVENTS ABI, as userspace expects register state to have been immediately modified. Userspace may opt-in for the payload deferral behavior with the KVM_CAP_EXCEPTION_PAYLOAD per-VM capability. As such, kvm_multiple_exception() will immediately manipulate guest registers if the capability hasn't been requested. Since the deferral is only necessary if a userspace ioctl were to be serviced at the same as a payload bearing exception is recognized, this behavior can be relaxed. Instead, opportunistically defer the payload from kvm_multiple_exception() and deliver the payload before completing a KVM_GET_VCPU_EVENTS ioctl. Signed-off-by: Oliver Upton <oupton@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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