> On Apr 30, 2019, at 1:27 PM, Sean Christopherson <sean.j.christopherson@xxxxxxxxx> wrote: > > On Tue, Apr 30, 2019 at 05:27:01AM -0700, nadav.amit@xxxxxxxxx wrote: >> From: Nadav Amit <nadav.amit@xxxxxxxxx> >> >> According to the SDM, during initialization, the BSP "Switches to >> protected mode and ensures that the APIC address space is mapped to the >> strong uncacheable (UC) memory type." >> >> This requirement is not followed when the tests relocate the APIC. Set >> the cache-disable flag while the APIC base is reprogrammed. According >> to the SDM, the MTRRs should be modified as well, but it seems somewhat >> complicated to do that and probably unnecessary. > > Alternatively, what about defining ALTERNATE_APIC_BASE to a sane value > that is guaranteed to be UC (assuming BIOS isn't being mean)? Maybe a > use well-known address, e.g. 0xfed40000 from the TPM, so as to avoid any > other unwanted side effects. Cool. This solution is much better than mine and it works for me. I’ll send a different patch instead.
