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KVM: introduce gfn_to_hva_read/kvm_read_hva/kvm_read_hva_atomic

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This set of functions is only used to read data from host space, in the
later patch, we will only get a readonly hva in gfn_to_hva_read, and
the function name is a good hint to let gfn_to_hva_read to pair with
kvm_read_hva()/kvm_read_hva_atomic()

Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Xiao Guangrong 2012-08-21 10:59:53 +08:00 committed by Avi Kivity
parent 037d92dc5d
commit 86ab8cffb4
1 changed files with 23 additions and 4 deletions
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27
virt/kvm/kvm_main.c
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@ -1002,6 +1002,25 @@ unsigned long gfn_to_hva(struct kvm *kvm, gfn_t gfn)
}
EXPORT_SYMBOL_GPL(gfn_to_hva);
/*
* The hva returned by this function is only allowed to be read.
* It should pair with kvm_read_hva() or kvm_read_hva_atomic().
*/
static unsigned long gfn_to_hva_read(struct kvm *kvm, gfn_t gfn)
{
return gfn_to_hva_many(gfn_to_memslot(kvm, gfn), gfn, NULL);
}
static int kvm_read_hva(void *data, void __user *hva, int len)
{
return __copy_from_user(data, hva, len);
}
static int kvm_read_hva_atomic(void *data, void __user *hva, int len)
{
return __copy_from_user_inatomic(data, hva, len);
}
int get_user_page_nowait(struct task_struct *tsk, struct mm_struct *mm,
unsigned long start, int write, struct page **page)
{
@ -1274,10 +1293,10 @@ int kvm_read_guest_page(struct kvm *kvm, gfn_t gfn, void *data, int offset,
int r;
unsigned long addr;
addr = gfn_to_hva(kvm, gfn);
addr = gfn_to_hva_read(kvm, gfn);
if (kvm_is_error_hva(addr))
return -EFAULT;
r = __copy_from_user(data, (void __user *)addr + offset, len);
r = kvm_read_hva(data, (void __user *)addr + offset, len);
if (r)
return -EFAULT;
return 0;
@ -1312,11 +1331,11 @@ int kvm_read_guest_atomic(struct kvm *kvm, gpa_t gpa, void *data,
gfn_t gfn = gpa >> PAGE_SHIFT;
int offset = offset_in_page(gpa);
addr = gfn_to_hva(kvm, gfn);
addr = gfn_to_hva_read(kvm, gfn);
if (kvm_is_error_hva(addr))
return -EFAULT;
pagefault_disable();
r = __copy_from_user_inatomic(data, (void __user *)addr + offset, len);
r = kvm_read_hva_atomic(data, (void __user *)addr + offset, len);
pagefault_enable();
if (r)
return -EFAULT;