Commit-ID: 4ec6e863625625a54f527464ab91ce1a1cb16c42 Gitweb: http://git.kernel.org/tip/4ec6e863625625a54f527464ab91ce1a1cb16c42 Author: Pan Xinhui <[email protected]> AuthorDate: Wed, 2 Nov 2016 05:08:34 -0400 Committer: Ingo Molnar <[email protected]> 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 <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Acked-by: Paolo Bonzini <[email protected]> Cc: [email protected] Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] [ Typo fixes. ] Signed-off-by: Ingo Molnar <[email protected]> --- 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,
