Hi Palmer, On Thu, Dec 7, 2023 at 1:07 AM Palmer Dabbelt <palmer@xxxxxxxxxxx> wrote: > > On Tue, 05 Dec 2023 23:41:55 PST (-0800), ebiggers@xxxxxxxxxx wrote: > > Hi Jerry, > > > > On Wed, Dec 06, 2023 at 03:02:40PM +0800, Jerry Shih wrote: > >> On Dec 6, 2023, at 08:46, Eric Biggers <ebiggers@xxxxxxxxxx> wrote: > >> > On Tue, Dec 05, 2023 at 05:27:49PM +0800, Jerry Shih wrote: > >> >> This series depend on: > >> >> 2. support kernel-mode vector > >> >> Link: https://lore.kernel.org/all/20230721112855.1006-1-andy.chiu@xxxxxxxxxx/ > >> >> 3. vector crypto extensions detection > >> >> Link: https://lore.kernel.org/lkml/20231017131456.2053396-1-cleger@xxxxxxxxxxxx/ > >> > > >> > What's the status of getting these prerequisites merged? > >> > > >> > - Eric > >> > >> The latest extension detection patch version is v5. > >> Link: https://lore.kernel.org/lkml/20231114141256.126749-1-cleger@xxxxxxxxxxxx/ > >> It's still under reviewing. > >> But I think the checking codes used in this crypto patch series will not change. > >> We could just wait and rebase when it's merged. > >> > >> The latest kernel-mode vector patch version is v3. > >> Link: https://lore.kernel.org/all/20231019154552.23351-1-andy.chiu@xxxxxxxxxx/ > >> This patch doesn't work with qemu(hit kernel panic when using vector). It's not > >> clear for the status. Could we still do the reviewing process for the gluing code and > >> the crypto asm parts? > > > > I'm almost ready to give my Reviewed-by for this whole series. The problem is > > that it can't be merged until its prerequisites are merged. > > > > Andy Chiu's last patchset "riscv: support kernel-mode Vector" was 2 months ago, > > but he also gave a talk at Plumbers about it more recently > > (https://www.youtube.com/watch?v=eht3PccEn5o). So I assume he's still working > > on it. It sounds like he's also going to include support for preemption, and > > optimizations to memcpy, memset, memmove, and copy_{to,from}_user. > > So I think we just got blocked on not knowing if turning on vector > everywhere in the kernel was a good idea -- it's not what any other port > does despite there having been some discussions floating around, but we > never really figured out why. I can come up with some possible > performance pathologies related to having vector on in many contexts, > but it's all theory as there's not really any vector hardware that works > upstream (though the K230 is starting to come along, so maybe that'll > sort itself out). > > Last we talked I think the general consensus is that we'd waited long > enough, if nobody has a concrete objection we should just take it and > see -- sure maybe there's some possible issues, but anything could have > issues. > > > I think it would be a good idea to split out the basic support for > > kernel_vector_{begin,end} so that the users of them, as well as the preemption > > support, can be considered and merged separately. Maybe patch 1 of the series > > (https://lore.kernel.org/r/20231019154552.23351-2-andy.chiu@xxxxxxxxxx) is all > > that's needed initially? > > I'm fine with that sort of approach too, it's certainly more in line > with other ports to just restrict the kernel-mode vector support to > explicitly enabled sections. Sure maybe there's other stuff to do in > kernel vector land, but we can at least get something going. With the current approach of preempt_v we still need kernel_vector_begin/end to explicitly mark enabled sections. But indeed, preempt_v will make it easy to do function-wise, thread-wise enable if people need it. > > > Andy, what do you think? > > I'll wait on Andy to see, but I generally agree we should merge > something for this cycle. > > Andy: maybe just send a patch set with what you think is the best way to > go? Then we have one target approach and we can get things moving. Yes, I think we can split. It will introduce some overhead on my side, but at least we can get some parts moving. I was preempted by some higher priority tasks. Luckily I am back now. Please expect v4 by next week, I hope it won't be too late for the cycle. > > > - Eric
