Messages in this thread Patch in this message | | | Date | Wed, 07 May 2014 15:57:43 +0200 | From | Paolo Bonzini <> | Subject | Re: [PATCH 1/5] KVM: x86: Emulator does not calculate address correctly |
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Il 07/05/2014 14:32, Nadav Amit ha scritto: > In long-mode, when the address size is 4 bytes, the linear address is not > truncated as the emulator mistakenly does. Instead, the offset within the > segment (the ea field) should be truncated according to the address size. > > As Intel SDM says: "In 64-bit mode, the effective address components are added > and the effective address is truncated ... before adding the full 64-bit > segment base." > > Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> > --- > arch/x86/kvm/emulate.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c > index e8a5840..743e8e3 100644 > --- a/arch/x86/kvm/emulate.c > +++ b/arch/x86/kvm/emulate.c > @@ -631,7 +631,8 @@ static int __linearize(struct x86_emulate_ctxt *ctxt, > u16 sel; > unsigned cpl; > > - la = seg_base(ctxt, addr.seg) + addr.ea; > + la = seg_base(ctxt, addr.seg) + > + (ctxt->ad_bytes == 8 ? addr.ea : (u32)addr.ea);
I think you need "fetch || ctxt->ad_bytes == 8" here.
Paolo
> switch (ctxt->mode) { > case X86EMUL_MODE_PROT64: > if (((signed long)la << 16) >> 16 != la) > @@ -678,7 +679,7 @@ static int __linearize(struct x86_emulate_ctxt *ctxt, > } > break; > } > - if (fetch ? ctxt->mode != X86EMUL_MODE_PROT64 : ctxt->ad_bytes != 8) > + if (ctxt->mode != X86EMUL_MODE_PROT64) > la &= (u32)-1; > if (insn_aligned(ctxt, size) && ((la & (size - 1)) != 0)) > return emulate_gp(ctxt, 0); >
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