On 26 January 2018 at 17:05, Will Deacon <will.deacon@xxxxxxx> wrote: > On Thu, Jan 25, 2018 at 10:31:31AM +0000, Ard Biesheuvel wrote: >> Now that all UEFI runtime service wrappers ensure that byref >> arguments are moved into the UEFI marshalling buffer (which >> is not part of the kernel mapping), we can proceed and unmap >> the kernel while UEFI runtime service calls are in progress. >> >> This is done by setting the EPD1 bit and flushing the TLB of >> the local CPU. This makes it independent of KPTI or whether >> non-global mappings are being used. > > One snag with this is that it will break SPE, so I'd prefer this behaviour > to be predicated on kpti so that the arm64_kernel_unmapped_at_el0() check > in drivers/perf/arm_spe_pmu.c remains valid. > The problem with that is that they serve two different purposes: kpti protects against meltdown, this protects against Spectre variant 1. -- 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
