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
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