On Tue, 25 Feb 2020 at 19:31, Ard Biesheuvel <ard.biesheu...@linaro.org> wrote: > > On Tue, 25 Feb 2020 at 19:28, Ard Biesheuvel <ard.biesheu...@linaro.org> > wrote: > > > > Cache maintenance operations by set/way are only intended to be used > > in the context of on/offlining a core, while it has been taken out of > > the coherency domain. Any use intended to ensure that the contents of > > the cache have made it to main memory is unreliable, since cacheline > > migration and non-architected system caches may cause these contents > > to linger elsewhere, without being visible in main memory once the > > MMU and caches are disabled. > > > > In KVM on Linux, there are horrid hacks in place to ensure that such > > set/way operations are trapped, and replaced with a single by-VA > > clean/invalidate of the entire guest VA space once the MMU state > > changes, which can be costly, and is unnecessary if we manage the > > caches a bit more carefully, and perform maintenance by virtual > > address only. > > > > So let's get rid of the call to ArmInvalidateDataCache () in the > > PrePeiCore startup code, and instead, invalidate the UEFI memory > > region by virtual address, which is the only memory region we will > > be touching with the caches and MMU both disabled and enabled. > > (This will lead to data corruption if data written with the MMU off > > is shadowed by clean, stale cachelines that stick around when the > > MMU is enabled again.) > > > > Signed-off-by: Ard Biesheuvel <ard.biesheu...@linaro.org> > > --- > > Forgot to add a note that this is the *PrePi* version, not the > PrePeiCore one that I sent before. > > @Pete: this might affect RPi3 and RPi4, and I am currently not able to > test it. If it's not too much trouble, I'd appreciate a Tested-by. If > not, I'll test it myself, but it may take me a while to get around to > it. >
Actually, I decided to dedicate some of my evening to have a go at this myself. This patch works for me on RPi4, as well as the BCM GENET with the latest changes, and the version of the driver that turned up in net-next today I am getting around 100 - 150 Mbit/s - is that what I should expect? -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#54805): https://edk2.groups.io/g/devel/message/54805 Mute This Topic: https://groups.io/mt/71538761/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
