On 03/14/2010 07:35 PM, Gleb Natapov wrote:
On Sun, Mar 14, 2010 at 06:54:11PM +0200, Avi Kivity wrote:
On 03/14/2010 06:21 PM, Gleb Natapov wrote:
in/out emulation is broken now. The breakage is different depending
on where IO device resides. If it is in userspace emulator reports
emulation failure since it incorrectly interprets kvm_emulate_pio()
return value. If IO device is in the kernel emulation of 'in' will do
nothing since kvm_emulate_pio() stores result directly into vcpu
registers, so emulator will overwrite result of emulation during
commit of shadowed register.
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 8f5e4c8..344e17b 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -210,13 +210,13 @@ static u32 opcode_table[256] = {
0, 0, 0, 0, 0, 0, 0, 0,
/* 0xE0 - 0xE7 */
0, 0, 0, 0,
- ByteOp | SrcImmUByte, SrcImmUByte,
- ByteOp | SrcImmUByte, SrcImmUByte,
+ ByteOp | SrcImmUByte | DstAcc, SrcImmUByte | DstAcc,
+ ByteOp | SrcImmUByte | DstAcc, SrcImmUByte | DstAcc,
REX prefix shouldn't expand DstAcc to 64 bits here. Might cause
problems further down in the pipeline.+
Is REX prefix allowed with this opcodes?
If yes:
if (c->dst.bytes == 8)
c->dst.bytes = 4;
inside IN/OUT emulation will fix this.
I don't know, but I guess REX is allowed and ignored.
--
Do not meddle in the internals of kernels, for they are subtle and quick to
panic.
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