On Mon, Dec 04, 2017 at 12:33:01PM -0600, Tom Lendacky wrote: > On 12/4/2017 10:34 AM, Kirill A. Shutemov wrote: > > On Mon, Dec 04, 2017 at 04:00:26PM +0000, Tom Lendacky wrote: > > > On 12/4/2017 8:57 AM, Kirill A. Shutemov wrote: > > > > On Mon, Dec 04, 2017 at 08:19:11AM -0600, Tom Lendacky wrote: > > > > > On 12/4/2017 5:23 AM, Kirill A. Shutemov wrote: > > > > > > sme_populate_pgd() open-codes a lot of things that are not needed to be > > > > > > open-coded. > > > > > > > > > > > > Let's rewrite it in a more stream-lined way. > > > > > > > > > > > > This would also buy us boot-time switching between support between > > > > > > paging modes, when rest of the pieces will be upstream. > > > > > > > > > > Hi Kirill, > > > > > > > > > > Unfortunately, some of these can't be changed. The use of p4d_offset(), > > > > > pud_offset(), etc., use non-identity mapped virtual addresses which cause > > > > > failures at this point of the boot process. > > > > > > > > Wat? Virtual address is virtual address. p?d_offset() doesn't care about > > > > what mapping you're using. > > > > > > Yes it does. For example, pmd_offset() issues a pud_page_addr() call, > > > which does a __va() returning a non-identity mapped address (0xffff88...). > > > Only identity mapped virtual addresses have been setup at this point, so > > > the use of that virtual address panics the kernel. > > > > Stupid me. You are right. > > > > What about something like this: > > > > diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c > > index d9a9e9fc75dd..65e0d68f863f 100644 > > --- a/arch/x86/mm/mem_encrypt.c > > +++ b/arch/x86/mm/mem_encrypt.c > > @@ -12,6 +12,23 @@ > > #define DISABLE_BRANCH_PROFILING > > +/* > > + * Since we're dealing with identity mappings, physical and virtual > > + * addresses are the same, so override these defines which are ultimately > > + * used by the headers in misc.h. > > + */ > > +#define __pa(x) ((unsigned long)(x)) > > +#define __va(x) ((void *)((unsigned long)(x))) > > No, you can't do this. There are routines in this file that are called > after the kernel has switched to its standard virtual address map where > this definition of __va() will likely cause a failure. Let's than split it up into separate compilation unit. > > +/* > > + * Special hack: we have to be careful, because no indirections are > > + * allowed here, and paravirt_ops is a kind of one. As it will only run in > > + * baremetal anyway, we just keep it from happening. (This list needs to > > + * be extended when new paravirt and debugging variants are added.) > > + */ > > +#undef CONFIG_PARAVIRT > > +#undef CONFIG_PARAVIRT_SPINLOCKS > > I'd really, really like to avoid doing something like this. Any other proposals? Current code is way too hairy and hard to modify. -- Kirill A. Shutemov -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
