On Fri, 04 Jun 2021 09:13:10 +0100, Shameerali Kolothum Thodi <shameerali.kolothum.thodi@xxxxxxxxxx> wrote: > > Hi, > > > -----Original Message----- > > From: Shameerali Kolothum Thodi > > Sent: 06 May 2021 17:52 > > To: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; kvmarm@xxxxxxxxxxxxxxxxxxxxx; > > linux-kernel@xxxxxxxxxxxxxxx > > Cc: maz@xxxxxxxxxx; will@xxxxxxxxxx; catalin.marinas@xxxxxxx; > > james.morse@xxxxxxx; julien.thierry.kdev@xxxxxxxxx; > > suzuki.poulose@xxxxxxx; jean-philippe@xxxxxxxxxx; Linuxarm > > <linuxarm@xxxxxxxxxx> > > Subject: [RFC PATCH 0/3] kvm/arm: New VMID allocator based on asid(2nd > > approach) > > > > This is based on a suggestion from Will [0] to try out the asid > > based kvm vmid solution as a separate VMID allocator instead of > > the shared lib approach attempted in v4[1]. > > > > The idea is to compare both the approaches and see whether the > > shared lib solution with callbacks make sense or not. > > A gentle ping on this. Please take a look and let me know. I had a look and I don't overly dislike it. I'd like to see the code without the pinned stuff though, at least to ease the reviewing. I haven't tested it in anger, but I have pushed the rebased code at [1] as it really didn't apply to 5.13-rc4. One thing I'm a bit worried about is that we so far relied on VMID 0 never being allocated to a guest, which is now crucial for protected KVM. I can't really convince myself that this can never happen with this. Plus, I've found this nugget: <quote max_pinned_vmids = NUM_USER_VMIDS - num_possible_cpus() - 2; </quote> What is this "- 2"? My hunch is that it should really be "- 1" as VMID 0 is reserved, and we have no equivalent of KPTI for S2. M. [1] https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/log/?h=kvm-arm64/mmu/vmid -- Without deviation from the norm, progress is not possible. _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
