Messages in this thread | | | Date | Fri, 20 Jul 2012 07:58:40 -0300 | From | Marcelo Tosatti <> | Subject | Re: [PATCH 2/9] KVM: x86: simplify read_emulated |
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On Fri, Jul 20, 2012 at 10:17:36AM +0800, Xiao Guangrong wrote: > On 07/20/2012 07:58 AM, Marcelo Tosatti wrote: > > >> - } > >> + rc = ctxt->ops->read_emulated(ctxt, addr, mc->data + mc->end, size, > >> + &ctxt->exception); > >> + if (rc != X86EMUL_CONTINUE) > >> + return rc; > >> + > >> + mc->end += size; > >> + > >> +read_cached: > >> + memcpy(dest, mc->data + mc->pos, size); > > > > What prevents read_emulated(size > 8) call, with > > mc->pos == (mc->end - 8) now? > > Marcelo, > > The splitting has been done in emulator_read_write_onepage: > > while (bytes) { > unsigned now = min(bytes, 8U); > > frag = &vcpu->mmio_fragments[vcpu->mmio_nr_fragments++]; > frag->gpa = gpa; > frag->data = val; > frag->len = now; > frag->write_readonly_mem = (ret == -EPERM); > > gpa += now; > val += now; > bytes -= now; > } > > So i think it is safe to remove the splitting in read_emulated.
Yes, it is fine to remove it.
But splitting in emulate.c prevented the case of _cache read_ with size > 8 beyond end of mc->data. Must handle that case in read_emulated.
"What prevents read_emulated(size > 8) call, with mc->pos == (mc->end - 8) now?"
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