On Thu, May 30, 2013 at 05:34:21PM +0200, Paolo Bonzini wrote:
> Il 30/05/2013 16:35, Paolo Bonzini ha scritto:
> > The x86-64 extended low-byte registers were fetched correctly from reg,
> > but not from mod/rm.
> >
> > This fixes another bug in the boot of RHEL5.9 64-bit, but it is still
> > not enough.
>
> Well, it is enough but it takes 2 minutes to reach the point where
> hardware virtualization is used. It is doing a lot of stuff in
> emulation mode because FS and GS have leftovers from the A20 test:
>
> FS =0000 0000000000000000 0000ffff 00009300 DPL=0 DS16 [-WA]
> GS =ffff 00000000000ffff0 0000ffff 00009300 DPL=0 DS16 [-WA]
>
> 0x00000000000113be: in $0x92,%al
> 0x00000000000113c0: or $0x2,%al
> 0x00000000000113c2: out %al,$0x92
> 0x00000000000113c4: xor %ax,%ax
> 0x00000000000113c6: mov %ax,%fs
> 0x00000000000113c8: dec %ax
> 0x00000000000113c9: mov %ax,%gs
> 0x00000000000113cb: inc %ax
> 0x00000000000113cc: mov %ax,%fs:0x200
> 0x00000000000113d0: cmp %gs:0x210,%ax
> 0x00000000000113d5: je 0x113cb
>
This is 16 bit code that sets them up. So 32bit transition code does not
reload them?
> The DPL < RPL test fails. Any ideas? Should we introduce a new
> intermediate value for emulate_invalid_guest_state (0=none, 1=some, 2=full)?
>
> Paolo
>
> > Cc: gnatapov@xxxxxxxxxx
> > Cc: kvm@xxxxxxxxxxxxxxx
> > Cc: <stable@xxxxxxxxxxxxxxx> # 3.9
> > Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> > ---
> > arch/x86/kvm/emulate.c | 5 ++++-
> > 1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> > index aa68106..028b34f 100644
> > --- a/arch/x86/kvm/emulate.c
> > +++ b/arch/x86/kvm/emulate.c
> > @@ -1239,9 +1239,12 @@ static int decode_modrm(struct x86_emulate_ctxt *ctxt,
> > ctxt->modrm_seg = VCPU_SREG_DS;
> >
> > if (ctxt->modrm_mod == 3) {
> > + int highbyte_regs = ctxt->rex_prefix == 0;
> > +
> > op->type = OP_REG;
> > op->bytes = (ctxt->d & ByteOp) ? 1 : ctxt->op_bytes;
> > - op->addr.reg = decode_register(ctxt, ctxt->modrm_rm, ctxt->d & ByteOp);
> > + op->addr.reg = decode_register(ctxt, ctxt->modrm_rm,
> > + highbyte_regs && (ctxt->d & ByteOp));
> > if (ctxt->d & Sse) {
> > op->type = OP_XMM;
> > op->bytes = 16;
> >
--
Gleb.
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