[PATCH v4 05/16] KVM: Annotate -EFAULTs from kvm_vcpu_write_guest_page()

[Anish Moorthy <amoorthy@google.com>]

Implement KVM_CAP_MEMORY_FAULT_INFO for uaccess failures in
kvm_vcpu_write_guest_page()

Signed-off-by: Anish Moorthy <amoorthy@google.com>
---
 virt/kvm/kvm_main.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index d9c0fa7c907f..ea27a8178f1a 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3090,8 +3090,10 @@ EXPORT_SYMBOL_GPL(kvm_vcpu_read_guest_atomic);
 
 /*
  * Copy 'len' bytes from 'data' into guest memory at '(gfn * PAGE_SIZE) + offset'
+ * If 'vcpu' is non-null, then may fill its run struct for a
+ * KVM_EXIT_MEMORY_FAULT on uaccess failure.
  */
-static int __kvm_write_guest_page(struct kvm *kvm,
+static int __kvm_write_guest_page(struct kvm *kvm, struct kvm_vcpu *vcpu,
 				  struct kvm_memory_slot *memslot, gfn_t gfn,
 			          const void *data, int offset, int len)
 {
@@ -3102,8 +3104,13 @@ static int __kvm_write_guest_page(struct kvm *kvm,
 	if (kvm_is_error_hva(addr))
 		return -EFAULT;
 	r = __copy_to_user((void __user *)addr + offset, data, len);
-	if (r)
+	if (r) {
+		if (vcpu)
+			kvm_populate_efault_info(vcpu, gfn * PAGE_SIZE + offset,
+						 len,
+						 KVM_MEMORY_FAULT_FLAG_WRITE);
 		return -EFAULT;
+	}
 	mark_page_dirty_in_slot(kvm, memslot, gfn);
 	return 0;
 }
@@ -3113,7 +3120,7 @@ int kvm_write_guest_page(struct kvm *kvm, gfn_t gfn,
 {
 	struct kvm_memory_slot *slot = gfn_to_memslot(kvm, gfn);
 
-	return __kvm_write_guest_page(kvm, slot, gfn, data, offset, len);
+	return __kvm_write_guest_page(kvm, NULL, slot, gfn, data, offset, len);
 }
 EXPORT_SYMBOL_GPL(kvm_write_guest_page);
 
@@ -3121,8 +3128,8 @@ int kvm_vcpu_write_guest_page(struct kvm_vcpu *vcpu, gfn_t gfn,
 			      const void *data, int offset, int len)
 {
 	struct kvm_memory_slot *slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
-
-	return __kvm_write_guest_page(vcpu->kvm, slot, gfn, data, offset, len);
+	return __kvm_write_guest_page(vcpu->kvm, vcpu, slot, gfn, data,
+				      offset, len);
 }
 EXPORT_SYMBOL_GPL(kvm_vcpu_write_guest_page);
 
-- 
2.41.0.rc0.172.g3f132b7071-goog