On Thu, Sep 23, 2021 at 08:21:03PM +0200, Borislav Petkov wrote: > On Thu, Sep 23, 2021 at 12:05:58AM +0300, Kirill A. Shutemov wrote: > > Unless we find other way to guarantee RIP-relative access, we must use > > fixup_pointer() to access any global variables. > > Yah, I've asked compiler folks about any guarantees we have wrt > rip-relative addresses but it doesn't look good. Worst case, we'd have > to do the fixup_pointer() thing. > > In the meantime, Tom and I did some more poking at this and here's a > diff ontop. > > The direction being that we'll stick both the AMD and Intel > *cc_platform_has() call into cc_platform.c for which instrumentation > will be disabled so no issues with that. > > And that will keep all that querying all together in a single file. And still do cc_platform_has() calls in __startup_64() codepath? It's broken. Intel detection in cc_platform_has() relies on boot_cpu_data.x86_vendor which is not initialized until early_cpu_init() in setup_arch(). Given that X86_VENDOR_INTEL is 0 it leads to false-positive. I think opencode these two calls is the way forward. Maybe also move the check from sme_encrypt_kernel() to __startup_64(). -- Kirill A. Shutemov
