> -Original Message-
> From: Will Deacon [mailto:w...@kernel.org]
> Sent: 03 August 2021 12:39
> To: Shameerali Kolothum Thodi
> Cc: linux-arm-ker...@lists.infradead.org; kvmarm@lists.cs.columbia.edu;
> linux-ker...@vger.kernel.org; m...@kernel.org; catalin.mari...@arm.com;
> james.mo...@arm.com; julien.thierry.k...@gmail.com;
> suzuki.poul...@arm.com; jean-phili...@linaro.org;
> alexandru.eli...@arm.com; qper...@google.com; Linuxarm
>
> Subject: Re: [PATCH v3 1/4] KVM: arm64: Introduce a new VMID allocator for
> KVM
>
> On Thu, Jul 29, 2021 at 11:40:06AM +0100, Shameer Kolothum wrote:
> > A new VMID allocator for arm64 KVM use. This is based on
> > arm64 ASID allocator algorithm.
> >
> > One major deviation from the ASID allocator is the way we
> > flush the context. Unlike ASID allocator, we expect less
> > frequent rollover in the case of VMIDs. Hence, instead of
> > marking the CPU as flush_pending and issuing a local context
> > invalidation on the next context switch, we broadcast TLB
> > flush + I-cache invalidation over the inner shareable domain
> > on rollover.
> >
> > Signed-off-by: Shameer Kolothum
>
> > ---
>
> [...]
>
> > +void kvm_arm_vmid_update(struct kvm_vmid *kvm_vmid)
> > +{
> > + unsigned long flags;
> > + unsigned int cpu;
> > + u64 vmid, old_active_vmid;
> > +
> > + vmid = atomic64_read(_vmid->id);
> > +
> > + /*
> > +* Please refer comments in check_and_switch_context() in
> > +* arch/arm64/mm/context.c.
> > +*/
> > + old_active_vmid = atomic64_read(this_cpu_ptr(_vmids));
> > + if (old_active_vmid && vmid_gen_match(vmid) &&
> > + atomic64_cmpxchg_relaxed(this_cpu_ptr(_vmids),
> > +old_active_vmid, vmid))
> > + return;
> > +
> > + raw_spin_lock_irqsave(_vmid_lock, flags);
> > +
> > + /* Check that our VMID belongs to the current generation. */
> > + vmid = atomic64_read(_vmid->id);
> > + if (!vmid_gen_match(vmid)) {
> > + vmid = new_vmid(kvm_vmid);
> > + atomic64_set(_vmid->id, vmid);
>
> new_vmid() can just set kvm_vmid->id directly
Ok.
>
> > + }
> > +
> > + cpu = smp_processor_id();
>
> Why?
Left over from previous one. Forgot to remove
as we don't have the tlb_flush_pending check anymore.
Thanks,
Shameer
>
> Will
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