Messages in this thread | | | From | "Ren, Qiaowei" <> | Subject | RE: [PATCH 4/4] driver: provide sysfs interfaces to access SMX parameter | Date | Fri, 10 May 2013 07:05:53 +0000 |
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On 2013-05-08, Matthew Garrett wrote: > On Tue, 2013-05-07 at 22:55 +0800, Qiaowei Ren wrote: > > > +What: /sys/devices/platform/intel_txt/parameter/acm_max_size > > +Date: May 2013 > > +KernelVersion: 3.9 > > +Contact: "Qiaowei Ren" <qiaowei.ren@intel.com> > > +Description: The "acm_max_size" property will show max size of > > + authenticated code execution area. > > What would userspace use this for?
These sysfs files are just export SMX & TXT related information to userspace. So that other developers (or OSV & ISV) can be able to develop txt related applications or tools based on these information.
> > +What: /sys/devices/platform/intel_txt/parameter/acm_mem_types > > +Date: May 2013 > > +KernelVersion: 3.9 > > +Contact: "Qiaowei Ren" <qiaowei.ren@intel.com> > > +Description: The "acm_max_types" property will show external memory > > + types supported during AC mode. > > Or this? And what's AC mode?
It means that the property will show supportable memory types for memory mapped outside of the authenticated code execution area.
> > + __asm__ __volatile__ (IA32_GETSEC_OPCODE "\n" > > + : "=a"(eax), "=b"(ebx), "=c"(ecx) > > + : "a"(IA32_GETSEC_PARAMETERS), "b"(index)); > > + > > + *param_type = eax & 0x1f; > > + *peax = eax; > > + *pebx = ebx; > > + *pecx = ecx; > > Should there be a check for failure here? Is it possible for this operation to fail?
You mean GETSEC instruction? I don't notice related description in manual. Next function get_parameters() will process return eax/ebx/ecx returned by this instruction.
> > + write_cr4(read_cr4() | CR4_SMXE); > > Whoo. This needs at least a giant comment and probably some locking, but if > this is supposed to be set during runtime then it should be done in core > architecture code rather than just in this driver.
Oh. This code should be removed, because tboot code have set SMXE bit.
Thanks, Qiaowei
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