Commit 4ec6e863 authored by Pan Xinhui's avatar Pan Xinhui Committed by Ingo Molnar
Browse files

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: default avatarPan Xinhui <xinhui.pan@linux.vnet.ibm.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Cc: David.Laight@ACULAB.COM
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: benh@kernel.crashing.org
Cc: boqun.feng@gmail.com
Cc: borntraeger@de.ibm.com
Cc: bsingharora@gmail.com
Cc: dave@stgolabs.net
Cc: jgross@suse.com
Cc: kernellwp@gmail.com
Cc: konrad.wilk@oracle.com
Cc: linuxppc-dev@lists.ozlabs.org
Cc: mpe@ellerman.id.au
Cc: paulmck@linux.vnet.ibm.com
Cc: paulus@samba.org
Cc: rkrcmar@redhat.com
Cc: virtualization@lists.linux-foundation.org
Cc: will.deacon@arm.com
Cc: xen-devel-request@lists.xenproject.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1478077718-37424-8-git-send-email-xinhui.pan@linux.vnet.ibm.com


[ Typo fixes. ]
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 446f3dc8

include/linux/kvm_host.h

+2 −0
Original line number Diff line number Diff line
@@ -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);

virt/kvm/kvm_main.c

+14 −6
Original line number Diff line number Diff line
@@ -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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