From: Steven Price <steven.price@arm.com>
Date: Mon, 21 Oct 2019 16:28:17 +0100
Subject: KVM: Implement kvm_put_guest()
Patch-mainline: v5.5-rc1
Git-commit: cac0f1b7285eaaf9a186c618c3a7304d82ed5493
References: bsc#1172197 jsc#SLE-13593

kvm_put_guest() is analogous to put_user() - it writes a single value to
the guest physical address. The implementation is built upon put_user()
and so it has the same single copy atomic properties.

Signed-off-by: Steven Price <steven.price@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Liang Yan <lyan@suse.com>
---
 include/linux/kvm_host.h |   22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -746,6 +746,28 @@ int kvm_write_guest_offset_cached(struct
 				  unsigned long len);
 int kvm_gfn_to_hva_cache_init(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
 			      gpa_t gpa, unsigned long len);
+
+#define __kvm_put_guest(kvm, gfn, offset, value, type)			\
+({									\
+	unsigned long __addr = gfn_to_hva(kvm, gfn);			\
+	type __user *__uaddr = (type __user *)(__addr + offset);	\
+	int __ret = -EFAULT;						\
+									\
+	if (!kvm_is_error_hva(__addr))					\
+		__ret = put_user(value, __uaddr);			\
+	if (!__ret)							\
+		mark_page_dirty(kvm, gfn);				\
+	__ret;								\
+})
+
+#define kvm_put_guest(kvm, gpa, value, type)				\
+({									\
+	gpa_t __gpa = gpa;						\
+	struct kvm *__kvm = kvm;					\
+	__kvm_put_guest(__kvm, __gpa >> PAGE_SHIFT,			\
+			offset_in_page(__gpa), (value), type);		\
+})
+
 int kvm_clear_guest_page(struct kvm *kvm, gfn_t gfn, int offset, int len);
 int kvm_clear_guest(struct kvm *kvm, gpa_t gpa, unsigned long len);
 struct kvm_memory_slot *gfn_to_memslot(struct kvm *kvm, gfn_t gfn);