On 08/06/2011 01:39 PM, Christoffer Dall wrote:
> This commit introduces the framework for guest memory management
> through the use of 2nd stage translation. Each VM has a pointer
> to a level-1 tabled (the pgd field in struct kvm_arch) which is
> used for the 2nd stage translations. Entries are added when handling
> guest faults (later patch) and the table itself can be allocated and
> freed through the following functions implemented in
> arch/arm/kvm/arm_mmu.c:
> - kvm_alloc_stage2_pgd(struct kvm *kvm);
> - kvm_free_stage2_pgd(struct kvm *kvm);
>
> Further, each entry in TLBs and caches are tagged with a VMID
> identifier in addition to ASIDs. The VMIDs are managed using
> a bitmap and assigned when creating the VM in kvm_arch_init_vm()
> where the 2nd stage pgd is also allocated. The table is freed in
> kvm_arch_destroy_vm(). Both functions are called from the main
> KVM code.
>
>
> +/**
> + * kvm_arch_init_vm - initializes a VM data structure
> + * @kvm: pointer to the KVM struct
> + */
> int kvm_arch_init_vm(struct kvm *kvm)
> {
> - return 0;
> + int ret = 0;
> + phys_addr_t pgd_phys;
> + unsigned long vmid;
> + unsigned long start, end;
> +
> +
> + mutex_lock(&kvm_vmids_mutex);
> + vmid = find_first_zero_bit(kvm_vmids, VMID_SIZE);
> + if (vmid>= VMID_SIZE) {
> + mutex_unlock(&kvm_vmids_mutex);
> + return -EBUSY;
> + }
> + __set_bit(vmid, kvm_vmids);
VMID_SIZE seems to be a bit low for comfort. I guess it's fine for a
start, but later on we'll have to recycle VMIDs, like we do for SVM ASIDs.
Is there not a risk of a user starting 255 tiny guests and denying other
users the ability to use kvm?
> + kvm->arch.vmid = vmid;
> + mutex_unlock(&kvm_vmids_mutex);
> +
> + ret = kvm_alloc_stage2_pgd(kvm);
> + if (ret)
> + goto out_fail_alloc;
> +
> + pgd_phys = virt_to_phys(kvm->arch.pgd);
> + kvm->arch.vttbr = pgd_phys& ((1LLU<< 40) - 1)& ~((2<< VTTBR_X) - 1);
> + kvm->arch.vttbr |= ((u64)vmid<< 48);
> +
> + start = (unsigned long)kvm,
> + end = start + sizeof(struct kvm);
> + ret = create_hyp_mappings(kvm_hyp_pgd, start, end);
> + if (ret)
> + goto out_fail_hyp_mappings;
> +
> + return ret;
> +out_fail_hyp_mappings:
> + remove_hyp_mappings(kvm_hyp_pgd, start, end);
> +out_fail_alloc:
> + clear_bit(vmid, kvm_vmids);
> + return ret;
> }
>
--
error compiling committee.c: too many arguments to function
