On Wed, Jun 14, 2017 at 03:40:28PM -0500, Tom Lendacky wrote:
> I was trying to keep all the logic for it here in the SME related files
> rather than put it in the iommu code itself. But it is easy enough to
> move if you think it's worth it.
Yes please - the less needlessly global symbols, the better.
> > Also, you said in another mail on this subthread that c->microcode
> > is not yet set. Are you saying, that the iommu init gunk runs before
> > init_amd(), where we do set c->microcode?
> >
> > If so, we can move the setting to early_init_amd() or so.
>
> I'll look into that.
And I don't think c->microcode is not set by the time we init the iommu
because, AFAICT, we do the latter in pci_iommu_init() and that's a
rootfs_initcall() which happens later then the CPU init stuff.
> I'll look into simplifying the checks.
Something like this maybe?
if (rev >= 0x1205)
return true;
if (rev <= 0x11ff && rev >= 0x1126)
return true;
return false;
> > WARNING: Use of volatile is usually wrong: see Documentation/process/volatile-considered-harmful.rst
> > #134: FILE: drivers/iommu/amd_iommu.c:866:
> > +static void build_completion_wait(struct iommu_cmd *cmd, volatile u64 *sem)
> >
>
> The semaphore area is written to by the device so the use of volatile is
> appropriate in this case.
Do you mean this is like the last exception case in that document above:
"
- Pointers to data structures in coherent memory which might be modified
by I/O devices can, sometimes, legitimately be volatile. A ring buffer
used by a network adapter, where that adapter changes pointers to
indicate which descriptors have been processed, is an example of this
type of situation."
?
If so, it did work fine until now, without the volatile. Why is it
needed now, all of a sudden?
--
Regards/Gruss,
Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
