On 07/12/17 14:11, Jan Beulich wrote: > Signed-off-by: Jan Beulich <jbeul...@suse.com> > --- > v3: New. > > --- a/xen/arch/x86/x86_emulate/x86_emulate.c > +++ b/xen/arch/x86/x86_emulate/x86_emulate.c > @@ -5047,6 +5047,24 @@ x86_emulate( > goto done; > break; > > + case 0xf8: /* swapgs */ > + generate_exception_if(!mode_64bit(), EXC_UD); > + generate_exception_if(!mode_ring0(), EXC_GP, 0); > + fail_if(!ops->read_segment || !ops->read_msr || > + !ops->write_segment || !ops->write_msr); > + if ( (rc = ops->read_segment(x86_seg_gs, &sreg, > + ctxt)) != X86EMUL_OKAY || > + (rc = ops->read_msr(MSR_SHADOW_GS_BASE, &msr_val, > + ctxt)) != X86EMUL_OKAY || > + (rc = ops->write_msr(MSR_SHADOW_GS_BASE, sreg.base, > + ctxt)) != X86EMUL_OKAY )
We need to unwind this write in the case of write_segment failing, or when the instruction restarts, state will be corrupt. ~Andrew > + goto done; > + sreg.base = msr_val; > + if ( (rc = ops->write_segment(x86_seg_gs, &sreg, > + ctxt)) != X86EMUL_OKAY ) > + goto done; > + break; > + > case 0xf9: /* rdtscp */ > fail_if(ops->read_msr == NULL); > if ( (rc = ops->read_msr(MSR_TSC_AUX, > > > _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
