When a memslot has the KVM_MEM_MEMORY_FAULT_EXIT flag set, exit to
userspace upon encountering a page fault for which the userspace
page tables do not contain a present mapping.
Signed-off-by: Anish Moorthy <amoorthy@xxxxxxxxxx>
Acked-by: James Houghton <jthoughton@xxxxxxxxxx>
---
arch/arm64/kvm/arm.c | 1 +
arch/arm64/kvm/mmu.c | 14 ++++++++++++--
2 files changed, 13 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 3bd732eaf0872..f8337e757c777 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -220,6 +220,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
case KVM_CAP_VCPU_ATTRIBUTES:
case KVM_CAP_PTP_KVM:
case KVM_CAP_ARM_SYSTEM_SUSPEND:
+ case KVM_CAP_MEMORY_FAULT_NOWAIT:
r = 1;
break;
case KVM_CAP_SET_GUEST_DEBUG2:
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 735044859eb25..0d04ffc81f783 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -1206,6 +1206,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
unsigned long vma_pagesize, fault_granule;
enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_R;
struct kvm_pgtable *pgt;
+ bool exit_on_memory_fault = kvm_slot_fault_on_absent_mapping(memslot);
fault_granule = 1UL << ARM64_HW_PGTABLE_LEVEL_SHIFT(fault_level);
write_fault = kvm_is_write_fault(vcpu);
@@ -1303,8 +1304,17 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
*/
smp_rmb();
- pfn = __gfn_to_pfn_memslot(memslot, gfn, false, false, NULL,
- write_fault, &writable, NULL);
+ pfn = __gfn_to_pfn_memslot(
+ memslot, gfn, exit_on_memory_fault, false, NULL,
+ write_fault, &writable, NULL);
+
+ if (exit_on_memory_fault && pfn == KVM_PFN_ERR_FAULT) {
+ vcpu->run->exit_reason = KVM_EXIT_MEMORY_FAULT;
+ vcpu->run->memory_fault.flags = 0;
+ vcpu->run->memory_fault.gpa = gfn << PAGE_SHIFT;
+ vcpu->run->memory_fault.len = vma_pagesize;
+ return 0;
+ }
if (pfn == KVM_PFN_ERR_HWPOISON) {
kvm_send_hwpoison_signal(hva, vma_shift);
return 1;
--
2.40.0.rc1.284.g88254d51c5-goog
