[PATCH v6 04/10] KVM: Implement kvm_put_guest()

Steven Price
2019-10-11T13:00:18Z

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>
---
include/linux/kvm_host.h | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index fcb46b3374c6..bf0ae1825b9c 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -746,6 +746,28 @@ int kvm_write_guest_offset_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
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);
--
2.20.1