On 03/31/2011 11:42 AM, Roedel, Joerg wrote:
On Thu, Mar 31, 2011 at 05:18:28AM -0400, Avi Kivity wrote: > On 03/31/2011 09:14 AM, Roedel, Joerg wrote: > > On Mon, Mar 28, 2011 at 08:28:12AM -0400, Avi Kivity wrote: > > > The spec indicates we need to check the TSS and IOPL based permissions > > > before the intercept (vmx agrees). With the code as is, it happens > > > afterwards. > > > > > > One way to do this is to have an ExtraChecks bit in the opcode::flags. > > > Then opcode::u.xcheck->perms() is the pre-intercept check and > > > opcode::u.xcheck->execute() is the post-intercept execution. Should > > > work for monitor/mwait/rdtsc(p)/rdpmc/other crap x86 throws at us. > > > > Okay, as you suggested, I put these checks into the instruction emulator > > and let the hard work of implementing per-arch checks to the nested-vmx > > people ;) > > I doubt that this makes the opcode-tables more readable, but lets see :) > > I think we're miscommunicating. I'm talking about x86 checks, not virt > vendor specific checks. The place of the intercept check may be vendor specific. I havn't looked at the Intel spec, though. But there are probably differences.
That's why there are three hooks: pre-ex, post-ex, post-mem. If an intercept fits in between, use the pre-ex hook and duplicate the checks in the intercept.
As far as I recall, everything should fit into those three, though.
> For example, the flow for IOIO would be: > > #UD check (lock prefix) > PE/IOPL/CPL/VM check > TSS bitmap check (can cause #PF) > Intercept check > Operand segment check > Possible #PF > Execution > > We need to make sure the TSS bitmap check happens before the intercept, > so we need to split ->execute() into two. Right. For the generic case, how about factor out the checks (for the POST_EX intercept case) into a seperate excp_check-callback (similar to the execute-callback) and execute it before the post-exception-intercept check?
That is exactly my suggestion. -- error compiling committee.c: too many arguments to function -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
