On Mon, May 02, 2016 at 12:02:22PM +0200, Borislav Petkov wrote: > On Fri, Apr 29, 2016 at 10:41:19AM -0500, Alex Thorlton wrote: > > You can see here that we've made it past the MMR read in uv_system_init, > > but we die inside of our first EFI callback. In this example, it looks > > like we're using the kernel page table at the time of the failure, and I > > believe that the failing address is somewhere in our EFI runtime code: > > I think I see what's going on: > > [ 5.367290] PGD 1f81067 PUD 87ffff067 PMD 87fff8067 PTE 0 > > PTE 0 because, most probably, you need to sync > efi_sync_low_kernel_mappings(). Why? > > So the point of time this call is done, is, IINM, after we have > enabled virtual mode. I.e., it is being done in start_kernel() and > your callstack points at rest_init() which happens later in that same > function. > > So IMO what you should be doing, instead, is doing efi_call_virt() in > uv_bios_call() which should take care of everything. > > I think this naked efi_call() in uv_bios_call() should not be there > but UV should be calling the _phys or _virt helpers from the EFI core. > > Preferrably someone should go and audit all those EFI calls in UV and > figure out which one to use, _phys or _virt depending on the point in > time this call is being done. I think you're definitely right about needing to switch to something closer to the efi_call_virt/phys macros, but those, unfortunately, don't work right out of the box. The efi_call_virt macro assumes that the function pointer being passed in is in efi.systab, but our function pointer is in efi.uv_systab. I'm working on getting a slightly modified efi_call_virt working, but am having some problems with it. I've got it switching over to the EFI page table, but it's still giving me a bad paging request while trying to call into our EFI code. > For example, uv_system_init() should all be _virt calls, obviously. > And from a quick scan, most of the EFI calls are coming from there so > everything should be _virt. I'll make sure we take a look at this once we've sorted out our other issues. Thanks for pointing this out! > Btw, uv_bios_call_reentrant() looks unused, might want to remove it > while at it. I'll be sure to check this out as well. Thanks for the help. I'll get back to you when I know a bit more about what's happening with our runtime callbacks! - Alex -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
