[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v2] x86emul: add "unblock NMI" retire flag
On 11/04/17 16:36, Jan Beulich wrote: > No matter that we emulate IRET for (guest) real more only right now, we > should get its effect on (virtual) NMI delivery right. > > Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx> > --- > v2: Adjust x86_emulate_wrapper() accordingly. > > --- a/xen/arch/x86/hvm/emulate.c > +++ b/xen/arch/x86/hvm/emulate.c > @@ -1955,25 +1955,32 @@ static int _hvm_emulate_one(struct hvm_e > memcpy(vio->mmio_insn, hvmemul_ctxt->insn_buf, vio->mmio_insn_bytes); > } > > - if ( rc != X86EMUL_OKAY ) > - return rc; > + new_intr_shadow = hvmemul_ctxt->intr_shadow; > > - if ( hvmemul_ctxt->ctxt.retire.singlestep ) > - hvm_inject_hw_exception(TRAP_debug, X86_EVENT_NO_EC); > + /* > + * IRET, if valid in the given context, clears NMI blocking > + * (irrespective of rc). > + */ > + if ( hvmemul_ctxt->ctxt.retire.unblock_nmi ) > + new_intr_shadow &= ~HVM_INTR_SHADOW_NMI; > > - new_intr_shadow = hvmemul_ctxt->intr_shadow; > + if ( rc == X86EMUL_OKAY ) > + { On further thought, given the assertion, you don't need to introduce this check, and can avoid the block indentation. It should make the patch rather smaller. > + if ( hvmemul_ctxt->ctxt.retire.singlestep ) > + hvm_inject_hw_exception(TRAP_debug, X86_EVENT_NO_EC); > > - /* MOV-SS instruction toggles MOV-SS shadow, else we just clear it. */ > - if ( hvmemul_ctxt->ctxt.retire.mov_ss ) > - new_intr_shadow ^= HVM_INTR_SHADOW_MOV_SS; > - else > - new_intr_shadow &= ~HVM_INTR_SHADOW_MOV_SS; > - > - /* STI instruction toggles STI shadow, else we just clear it. */ > - if ( hvmemul_ctxt->ctxt.retire.sti ) > - new_intr_shadow ^= HVM_INTR_SHADOW_STI; > - else > - new_intr_shadow &= ~HVM_INTR_SHADOW_STI; > + /* MOV-SS instruction toggles MOV-SS shadow, else we just clear it. > */ > + if ( hvmemul_ctxt->ctxt.retire.mov_ss ) > + new_intr_shadow ^= HVM_INTR_SHADOW_MOV_SS; > + else > + new_intr_shadow &= ~HVM_INTR_SHADOW_MOV_SS; > + > + /* STI instruction toggles STI shadow, else we just clear it. */ > + if ( hvmemul_ctxt->ctxt.retire.sti ) > + new_intr_shadow ^= HVM_INTR_SHADOW_STI; > + else > + new_intr_shadow &= ~HVM_INTR_SHADOW_STI; > + } > > if ( hvmemul_ctxt->intr_shadow != new_intr_shadow ) > { > @@ -1981,13 +1988,11 @@ static int _hvm_emulate_one(struct hvm_e > hvm_funcs.set_interrupt_shadow(curr, new_intr_shadow); > } > > - if ( hvmemul_ctxt->ctxt.retire.hlt && > + if ( rc == X86EMUL_OKAY && hvmemul_ctxt->ctxt.retire.hlt && > !hvm_local_events_need_delivery(curr) ) Similarly, you don't need the OKAY check here. Otherwise, Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> > - { > hvm_hlt(regs->eflags); > - } > > - return X86EMUL_OKAY; > + return rc; > } > > int hvm_emulate_one( > --- a/xen/arch/x86/x86_emulate/x86_emulate.c > +++ b/xen/arch/x86/x86_emulate/x86_emulate.c > @@ -4002,6 +4002,7 @@ x86_emulate( > uint32_t mask = X86_EFLAGS_VIP | X86_EFLAGS_VIF | X86_EFLAGS_VM; > > fail_if(!in_realmode(ctxt, ops)); > + ctxt->retire.unblock_nmi = true; > if ( (rc = read_ulong(x86_seg_ss, sp_post_inc(op_bytes), > &eip, op_bytes, ctxt, ops)) || > (rc = read_ulong(x86_seg_ss, sp_post_inc(op_bytes), > @@ -7918,9 +7919,17 @@ int x86_emulate_wrapper( > > rc = x86_emulate(ctxt, ops); > > - /* Retire flags should only be set for successful instruction emulation. > */ > + /* > + * Most retire flags should only be set for successful instruction > + * emulation. > + */ > if ( rc != X86EMUL_OKAY ) > - ASSERT(ctxt->retire.raw == 0); > + { > + typeof(ctxt->retire) retire = ctxt->retire; > + > + retire.unblock_nmi = false; > + ASSERT(!retire.raw); > + } > > /* All cases returning X86EMUL_EXCEPTION should have fault semantics. */ > if ( rc == X86EMUL_EXCEPTION ) > --- a/xen/arch/x86/x86_emulate/x86_emulate.h > +++ b/xen/arch/x86/x86_emulate/x86_emulate.h > @@ -490,6 +490,7 @@ struct x86_emulate_ctxt > bool hlt:1; /* Instruction HLTed. */ > bool mov_ss:1; /* Instruction sets MOV-SS irq shadow. */ > bool sti:1; /* Instruction sets STI irq shadow. */ > + bool unblock_nmi:1; /* Instruction clears NMI blocking. */ > bool singlestep:1; /* Singlestepping was active. */ > }; > } retire; > > _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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