Messages in this thread | | | Date | Wed, 8 Apr 2020 11:56:04 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 3/4] x86,module: Detect VMX vs SLD conflicts |
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On Wed, Apr 08, 2020 at 05:09:34PM +0900, Masami Hiramatsu wrote: > On Tue, 07 Apr 2020 13:02:39 +0200 > Peter Zijlstra <peterz@infradead.org> wrote: > > > +static bool insn_is_vmx(struct insn *insn) > > +{ > > + u8 modrm = insn->modrm.bytes[0]; > > + u8 modrm_mod = X86_MODRM_MOD(modrm); > > + u8 modrm_reg = X86_MODRM_REG(modrm); > > + > > + u8 prefix = insn->prefixes.bytes[0]; > > This should be the last prefix, > > u8 prefix = insn->prefixes.bytes[3]; > > (The last prefix always copied on the bytes[3])
And that is 0 on no-prefix, right?
> > + > > + if (insn->opcode.bytes[0] != 0x0f) > > + return false; > > + > > + switch (insn->opcode.bytes[1]) { > > + case 0x01: > > + switch (insn->opcode.bytes[2]) { > > Sorry, VMCALL etc. is in Grp7 (0f 01), the 3rd code is embedded > in modrm instead of opcode. Thus it should be, > > switch (insn->modrm.value) {
Indeed, I was hoping (I really should've checked) that that byte was duplicated in opcodes.
Also, since I already have modrm = insn->modrm.bytes[0], I should probably use that anyway.
> > + case 0xc1: /* VMCALL */ > > + case 0xc2: /* VMLAUNCH */ > > + case 0xc3: /* VMRESUME */ > > + case 0xc4: /* VMXOFF */ > > case 0xd4: /* VMFUNC */
As per Andrew, VMCALL and VMFUNC are SMV, and I really only need VMX in this case. Including SMV is probably harmless, but I'm thinking a smaller function is better.
> > + return true; > > + > > + default: > > + break; > > + } > > + break; > > + > > + case 0x78: /* VMREAD */ > > + case 0x79: /* VMWRITE */ > > return !insn_is_evex(insn); > > With EVEX prefix, these becomes vcvt* instructions.
Thanks!
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