Commit-ID: 4ec6e863625625a54f527464ab91ce1a1cb16c42
Gitweb: http://git.kernel.org/tip/4ec6e863625625a54f527464ab91ce1a1cb16c42
Author: Pan Xinhui <xinhui.pan@xxxxxxxxxxxxxxxxxx>
AuthorDate: Wed, 2 Nov 2016 05:08:34 -0400
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Tue, 22 Nov 2016 12:48:07 +0100
kvm: Introduce kvm_write_guest_offset_cached()
It allows us to update some status or field of a structure partially.
We can also save a kvm_read_guest_cached() call if we just update one
fild of the struct regardless of its current value.
Signed-off-by: Pan Xinhui <xinhui.pan@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Acked-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: David.Laight@xxxxxxxxxx
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: benh@xxxxxxxxxxxxxxxxxxx
Cc: boqun.feng@xxxxxxxxx
Cc: borntraeger@xxxxxxxxxx
Cc: bsingharora@xxxxxxxxx
Cc: dave@xxxxxxxxxxxx
Cc: jgross@xxxxxxxx
Cc: kernellwp@xxxxxxxxx
Cc: konrad.wilk@xxxxxxxxxx
Cc: linuxppc-dev@xxxxxxxxxxxxxxxx
Cc: mpe@xxxxxxxxxxxxxx
Cc: paulmck@xxxxxxxxxxxxxxxxxx
Cc: paulus@xxxxxxxxx
Cc: rkrcmar@xxxxxxxxxx
Cc: virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
Cc: will.deacon@xxxxxxx
Cc: xen-devel-request@xxxxxxxxxxxxxxxxxxxx
Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/1478077718-37424-8-git-send-email-xinhui.pan@xxxxxxxxxxxxxxxxxx
[ Typo fixes. ]
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
include/linux/kvm_host.h | 2 ++
virt/kvm/kvm_main.c | 20 ++++++++++++++------
2 files changed, 16 insertions(+), 6 deletions(-)
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 01c0b9c..6f00237 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -645,6 +645,8 @@ int kvm_write_guest(struct kvm *kvm, gpa_t gpa, const void *data,
unsigned long len);
int kvm_write_guest_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
void *data, unsigned long len);
+int kvm_write_guest_offset_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
+ void *data, int offset, 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);
int kvm_clear_guest_page(struct kvm *kvm, gfn_t gfn, int offset, int len);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 5c36034..2f38ce5 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1972,30 +1972,38 @@ int kvm_gfn_to_hva_cache_init(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
}
EXPORT_SYMBOL_GPL(kvm_gfn_to_hva_cache_init);
-int kvm_write_guest_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
- void *data, unsigned long len)
+int kvm_write_guest_offset_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
+ void *data, 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)
kvm_gfn_to_hva_cache_init(kvm, ghc, ghc->gpa, ghc->len);
if (unlikely(!ghc->memslot))
- return kvm_write_guest(kvm, ghc->gpa, data, len);
+ return kvm_write_guest(kvm, gpa, data, len);
if (kvm_is_error_hva(ghc->hva))
return -EFAULT;
- r = __copy_to_user((void __user *)ghc->hva, data, len);
+ r = __copy_to_user((void __user *)ghc->hva + offset, data, len);
if (r)
return -EFAULT;
- mark_page_dirty_in_slot(ghc->memslot, ghc->gpa >> PAGE_SHIFT);
+ mark_page_dirty_in_slot(ghc->memslot, gpa >> PAGE_SHIFT);
return 0;
}
+EXPORT_SYMBOL_GPL(kvm_write_guest_offset_cached);
+
+int kvm_write_guest_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
+ void *data, unsigned long len)
+{
+ return kvm_write_guest_offset_cached(kvm, ghc, data, 0, len);
+}
EXPORT_SYMBOL_GPL(kvm_write_guest_cached);
int kvm_read_guest_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc,
--
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