Messages in this thread | | | Date | Wed, 07 May 2014 18:21:25 +0300 | From | Nadav Amit <> | Subject | Re: [PATCH 1/5] KVM: x86: Emulator does not calculate address correctly |
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On 5/7/14, 4:57 PM, Paolo Bonzini wrote: > 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 > Yes. I did not test the fetch scenario. I intend to do so soon to avoid such mistakes.
Nadav
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