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KVM: x86/emulator: Move the unhandled outer privilege level logic of far return into __load_segment_descriptor()

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Outer-privilege level return is not implemented in emulator,
move the unhandled logic into __load_segment_descriptor to
make it easier to understand why the checks for RET are
incomplete.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
Message-Id: <5b7188e6388ac9f4567d14eab32db9adf3e00119.1644292363.git.houwenlong.hwl@antgroup.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Hou Wenlong 2022-02-08 17:34:05 +08:00 committed by Paolo Bonzini
parent 31c66dabaa
commit 1e326ad429
1 changed files with 8 additions and 6 deletions
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14
arch/x86/kvm/emulate.c
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@ -1623,9 +1623,14 @@ static int __load_segment_descriptor(struct x86_emulate_ctxt *ctxt,
if (!(seg_desc.type & 8))
goto exception;
/* RET can never return to an inner privilege level. */
if (transfer == X86_TRANSFER_RET && rpl < cpl)
goto exception;
if (transfer == X86_TRANSFER_RET) {
/* RET can never return to an inner privilege level. */
if (rpl < cpl)
goto exception;
/* Outer-privilege level return is not implemented */
if (rpl > cpl)
return X86EMUL_UNHANDLEABLE;
}
if (transfer == X86_TRANSFER_RET || transfer == X86_TRANSFER_TASK_SWITCH) {
if (seg_desc.type & 4) {
/* conforming */
@ -2220,9 +2225,6 @@ static int em_ret_far(struct x86_emulate_ctxt *ctxt)
rc = emulate_pop(ctxt, &cs, ctxt->op_bytes);
if (rc != X86EMUL_CONTINUE)
return rc;
/* Outer-privilege level return is not implemented */
if (ctxt->mode >= X86EMUL_MODE_PROT16 && (cs & 3) > cpl)
return X86EMUL_UNHANDLEABLE;
rc = __load_segment_descriptor(ctxt, (u16)cs, VCPU_SREG_CS, cpl,
X86_TRANSFER_RET,
&new_desc);