Right now userspace just gets a bare EFAULT when the stage-2 fault
handler fails to fault in the relevant page. Set up a
KVM_EXIT_MEMORY_FAULT whenever this happens, which at the very least
eases debugging and might also let userspace decide on/take some
specific action other than crashing the VM.
In some cases, user_mem_abort() EFAULTs before the size of the fault is
calculated: return 0 in these cases to indicate that the fault is of
unknown size.
Signed-off-by: Anish Moorthy <amoorthy@xxxxxxxxxx>
---
Documentation/virt/kvm/api.rst | 2 +-
arch/arm64/kvm/arm.c | 1 +
arch/arm64/kvm/mmu.c | 11 ++++++++++-
3 files changed, 12 insertions(+), 2 deletions(-)
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index c5ce7944005c..7b321fefcb3e 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -8129,7 +8129,7 @@ unavailable to host or other VMs.
7.34 KVM_CAP_MEMORY_FAULT_INFO
------------------------------
-:Architectures: x86
+:Architectures: arm64, x86
:Returns: Informational only, -EINVAL on direct KVM_ENABLE_CAP.
The presence of this capability indicates that KVM_RUN *may* fill
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index a7ca776b51ec..4121b5a43b9c 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -335,6 +335,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
case KVM_CAP_ARM_SYSTEM_SUSPEND:
case KVM_CAP_IRQFD_RESAMPLE:
case KVM_CAP_COUNTER_OFFSET:
+ case KVM_CAP_MEMORY_FAULT_INFO:
r = 1;
break;
case KVM_CAP_SET_GUEST_DEBUG2:
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 6981b1bc0946..c97199d1feac 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -1448,6 +1448,8 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
if (fault_is_perm && !write_fault && !exec_fault) {
kvm_err("Unexpected L2 read permission error\n");
+ kvm_prepare_memory_fault_exit(vcpu, fault_ipa, 0,
+ write_fault, exec_fault, false);
return -EFAULT;
}
@@ -1473,6 +1475,8 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
if (unlikely(!vma)) {
kvm_err("Failed to find VMA for hva 0x%lx\n", hva);
mmap_read_unlock(current->mm);
+ kvm_prepare_memory_fault_exit(vcpu, fault_ipa, 0,
+ write_fault, exec_fault, false);
return -EFAULT;
}
@@ -1568,8 +1572,11 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
kvm_send_hwpoison_signal(hva, vma_shift);
return 0;
}
- if (is_error_noslot_pfn(pfn))
+ if (is_error_noslot_pfn(pfn)) {
+ kvm_prepare_memory_fault_exit(vcpu, fault_ipa, vma_pagesize,
+ write_fault, exec_fault, false);
return -EFAULT;
+ }
if (kvm_is_device_pfn(pfn)) {
/*
@@ -1643,6 +1650,8 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
if (mte_allowed) {
sanitise_mte_tags(kvm, pfn, vma_pagesize);
} else {
+ kvm_prepare_memory_fault_exit(vcpu, fault_ipa, vma_pagesize,
+ write_fault, exec_fault, false);
ret = -EFAULT;
goto out_unlock;
}
--
2.46.0.76.ge559c4bf1a-goog
