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KVM: propagate fault r/w information to gup(), allow read-only memory

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As suggested by Andrea, pass r/w error code to gup(), upgrading read fault
to writable if host pte allows it.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Marcelo Tosatti
2010-10-22 14:18:18 -02:00
committed by Avi Kivity
parent 7905d9a5ad
commit 612819c3c6
4 changed files with 71 additions and 25 deletions
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51
virt/kvm/kvm_main.c
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@@ -959,7 +959,7 @@ static pfn_t get_fault_pfn(void)
}
static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr, bool atomic,
bool *async)
bool *async, bool write_fault, bool *writable)
{
struct page *page[1];
int npages = 0;
@@ -968,12 +968,34 @@ static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr, bool atomic,
/* we can do it either atomically or asynchronously, not both */
BUG_ON(atomic && async);
BUG_ON(!write_fault && !writable);
if (writable)
*writable = true;
if (atomic || async)
npages = __get_user_pages_fast(addr, 1, 1, page);
if (unlikely(npages != 1) && !atomic) {
might_sleep();
npages = get_user_pages_fast(addr, 1, 1, page);
if (writable)
*writable = write_fault;
npages = get_user_pages_fast(addr, 1, write_fault, page);
/* map read fault as writable if possible */
if (unlikely(!write_fault) && npages == 1) {
struct page *wpage[1];
npages = __get_user_pages_fast(addr, 1, 1, wpage);
if (npages == 1) {
*writable = true;
put_page(page[0]);
page[0] = wpage[0];
}
npages = 1;
}
}
if (unlikely(npages != 1)) {
@@ -1011,11 +1033,12 @@ static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr, bool atomic,
pfn_t hva_to_pfn_atomic(struct kvm *kvm, unsigned long addr)
{
return hva_to_pfn(kvm, addr, true, NULL);
return hva_to_pfn(kvm, addr, true, NULL, true, NULL);
}
EXPORT_SYMBOL_GPL(hva_to_pfn_atomic);
static pfn_t __gfn_to_pfn(struct kvm *kvm, gfn_t gfn, bool atomic, bool *async)
static pfn_t __gfn_to_pfn(struct kvm *kvm, gfn_t gfn, bool atomic, bool *async,
bool write_fault, bool *writable)
{
unsigned long addr;
@@ -1028,32 +1051,40 @@ static pfn_t __gfn_to_pfn(struct kvm *kvm, gfn_t gfn, bool atomic, bool *async)
return page_to_pfn(bad_page);
}
return hva_to_pfn(kvm, addr, atomic, async);
return hva_to_pfn(kvm, addr, atomic, async, write_fault, writable);
}
pfn_t gfn_to_pfn_atomic(struct kvm *kvm, gfn_t gfn)
{
return __gfn_to_pfn(kvm, gfn, true, NULL);
return __gfn_to_pfn(kvm, gfn, true, NULL, true, NULL);
}
EXPORT_SYMBOL_GPL(gfn_to_pfn_atomic);
pfn_t gfn_to_pfn_async(struct kvm *kvm, gfn_t gfn, bool *async)
pfn_t gfn_to_pfn_async(struct kvm *kvm, gfn_t gfn, bool *async,
bool write_fault, bool *writable)
{
return __gfn_to_pfn(kvm, gfn, false, async);
return __gfn_to_pfn(kvm, gfn, false, async, write_fault, writable);
}
EXPORT_SYMBOL_GPL(gfn_to_pfn_async);
pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn)
{
return __gfn_to_pfn(kvm, gfn, false, NULL);
return __gfn_to_pfn(kvm, gfn, false, NULL, true, NULL);
}
EXPORT_SYMBOL_GPL(gfn_to_pfn);
pfn_t gfn_to_pfn_prot(struct kvm *kvm, gfn_t gfn, bool write_fault,
bool *writable)
{
return __gfn_to_pfn(kvm, gfn, false, NULL, write_fault, writable);
}
EXPORT_SYMBOL_GPL(gfn_to_pfn_prot);
pfn_t gfn_to_pfn_memslot(struct kvm *kvm,
struct kvm_memory_slot *slot, gfn_t gfn)
{
unsigned long addr = gfn_to_hva_memslot(slot, gfn);
return hva_to_pfn(kvm, addr, false, NULL);
return hva_to_pfn(kvm, addr, false, NULL, true, NULL);
}
int gfn_to_page_many_atomic(struct kvm *kvm, gfn_t gfn, struct page **pages,