[PATCH 3/8] KVM: introduce kvm_read_guest_offset_cached()

Vitaly Kuznetsov
2020-05-11T16:48:30Z

We already have kvm_write_guest_offset_cached(), introduce read analogue.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
include/linux/kvm_host.h | 3 +++
virt/kvm/kvm_main.c | 19 ++++++++++++++-----
2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 01276e3d01b9..235109a23b8c 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -733,6 +733,9 @@ int kvm_read_guest_page(struct kvm *kvm, gfn_t gfn, void *data, int offset,
int kvm_read_guest(struct kvm *kvm, gpa_t gpa, void *data, unsigned long len);
int kvm_read_guest_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
void *data, unsigned long len);
+int kvm_read_guest_offset_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
+ void *data, unsigned int offset,
+ unsigned long len);
int kvm_write_guest_page(struct kvm *kvm, gfn_t gfn, const void *data,
int offset, int len);
int kvm_write_guest(struct kvm *kvm, gpa_t gpa, const void *data,
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 74bdb7bf3295..c425be6e6d98 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2503,13 +2503,15 @@ int kvm_write_guest_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
}
EXPORT_SYMBOL_GPL(kvm_write_guest_cached);

-int kvm_read_guest_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
- void *data, unsigned long len)
+int kvm_read_guest_offset_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
+ void *data, unsigned int offset,
+ unsigned long len)
{
struct kvm_memslots *slots = kvm_memslots(kvm);
int r;
+ gpa_t gpa = ghc->gpa + offset;

- BUG_ON(len > ghc->len);
+ BUG_ON(len + offset > ghc->len);

if (slots->generation != ghc->generation) {
if (__kvm_gfn_to_hva_cache_init(slots, ghc, ghc->gpa, ghc->len))
@@ -2520,14 +2522,21 @@ int kvm_read_guest_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
return -EFAULT;

if (unlikely(!ghc->memslot))
- return kvm_read_guest(kvm, ghc->gpa, data, len);
+ return kvm_read_guest(kvm, gpa, data, len);

- r = __copy_from_user(data, (void __user *)ghc->hva, len);
+ r = __copy_from_user(data, (void __user *)ghc->hva + offset, len);
if (r)
return -EFAULT;

return 0;
}
+EXPORT_SYMBOL_GPL(kvm_read_guest_offset_cached);
+
+int kvm_read_guest_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
+ void *data, unsigned long len)
+{
+ return kvm_read_guest_offset_cached(kvm, ghc, data, 0, len);
+}
EXPORT_SYMBOL_GPL(kvm_read_guest_cached);

int kvm_clear_guest_page(struct kvm *kvm, gfn_t gfn, int offset, int len)
--
2.25.4