On 06/03/2011 06:04 PM, Christoffer Dall wrote:
> Handles the guest faults in KVM by mapping in corresponding user pages
> in the 2nd stage page tables.
>
>
>
> +static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
> + gfn_t gfn, struct kvm_memory_slot *memslot)
> +{
> + pfn_t pfn;
> + pgd_t *pgd;
> + pmd_t *pmd;
> + pte_t *pte, new_pte;
> +
> + pfn = gfn_to_pfn(vcpu->kvm, gfn);
> +
> + if (is_error_pfn(pfn)) {
> + kvm_err(-EFAULT, "Guest gfn %u (0x%08lx) does not have "
> + "corresponding host mapping",
> + gfn, gfn<< PAGE_SHIFT);
> + return -EFAULT;
> + }
> +
> + /* Create 2nd stage page table mapping - Level 1 */
> + pgd = vcpu->kvm->arch.pgd + pgd_index(fault_ipa);
> + if (pgd_none(*pgd)) {
> + pmd = pmd_alloc_one(NULL, fault_ipa);
> + if (!pmd) {
> + kvm_err(-ENOMEM, "Cannot allocate 2nd stage pmd");
> + return -ENOMEM;
> + }
> + pgd_populate(NULL, pgd, pmd);
> + pmd += pmd_index(fault_ipa);
> + } else
> + pmd = pmd_offset(pgd, fault_ipa);
> +
> + /* Create 2nd stage page table mapping - Level 2 */
> + if (pmd_none(*pmd)) {
> + pte = pte_alloc_one_kernel(NULL, fault_ipa);
> + if (!pte) {
> + kvm_err(-ENOMEM, "Cannot allocate 2nd stage pte");
> + return -ENOMEM;
> + }
> + pmd_populate_kernel(NULL, pmd, pte);
> + pte += pte_index(fault_ipa);
> + } else
> + pte = pte_offset_kernel(pmd, fault_ipa);
> +
> + /* Create 2nd stage page table mapping - Level 3 */
> + new_pte = pfn_pte(pfn, PAGE_KVM_GUEST);
> + set_pte_ext(pte, new_pte, 0);
> +
> + return 0;
> +}
> +
> +#define HSR_ABT_FS (0x3f)
> +#define HPFAR_MASK (~0xf)
> int kvm_handle_guest_abort(struct kvm_vcpu *vcpu, struct kvm_run *run)
> {
> + unsigned long hsr_ec;
> + unsigned long fault_status;
> + phys_addr_t fault_ipa;
> + struct kvm_memory_slot *memslot = NULL;
> + bool is_iabt;
> + gfn_t gfn;
> +
> + hsr_ec = vcpu->arch.hsr>> HSR_EC_SHIFT;
> + is_iabt = (hsr_ec == HSR_EC_IABT);
> +
> + /* Check that the second stage fault is a translation fault */
> + fault_status = vcpu->arch.hsr& HSR_ABT_FS;
> + if ((fault_status& 0x3c) != 0x4) {
> + kvm_err(-EFAULT, "Unsupported fault status: %x",
> + fault_status& 0x3c);
> + return -EFAULT;
> + }
> +
> + fault_ipa = ((phys_addr_t)vcpu->arch.hpfar& HPFAR_MASK)<< 8;
> +
> + gfn = fault_ipa>> PAGE_SHIFT;
> + if (!kvm_is_visible_gfn(vcpu->kvm, gfn))
> + goto io_mem_abort;
> +
> + memslot = gfn_to_memslot(vcpu->kvm, gfn);
> + if (memslot->user_alloc)
> + return user_mem_abort(vcpu, fault_ipa, gfn, memslot);
Non-user_alloc should not exist for ARM (and are not supported for x86
these days, except for a few implementation internal slots).
> +
> +io_mem_abort:
> + if (is_iabt) {
> + kvm_err(-EFAULT, "Inst. abort on I/O address");
> + return -EFAULT;
> + }
> +
> + kvm_msg("I/O address abort...");
> KVMARM_NOT_IMPLEMENTED();
> return -EINVAL;
> }
Okay, this is about a zillion times simpler than x86. Congratulations.
What are your thoughts about mmu notifier support?
--
error compiling committee.c: too many arguments to function
