KVM: MMU: Split the main body of rmap_write_protect() off from others
We will use this in the following patch to implement another function
which needs to write protect pages using the rmap information.
Note that there is a small change in debug printing for large pages:
we do not differentiate them from others to avoid duplicating code.
Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 4cb1642..c8b5694 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1010,42 +1010,43 @@
rmap_remove(kvm, sptep);
}
+static int __rmap_write_protect(struct kvm *kvm, unsigned long *rmapp, int level)
+{
+ u64 *spte = NULL;
+ int write_protected = 0;
+
+ while ((spte = rmap_next(rmapp, spte))) {
+ BUG_ON(!(*spte & PT_PRESENT_MASK));
+ rmap_printk("rmap_write_protect: spte %p %llx\n", spte, *spte);
+
+ if (!is_writable_pte(*spte))
+ continue;
+
+ if (level == PT_PAGE_TABLE_LEVEL) {
+ mmu_spte_update(spte, *spte & ~PT_WRITABLE_MASK);
+ } else {
+ BUG_ON(!is_large_pte(*spte));
+ drop_spte(kvm, spte);
+ --kvm->stat.lpages;
+ spte = NULL;
+ }
+
+ write_protected = 1;
+ }
+
+ return write_protected;
+}
+
int kvm_mmu_rmap_write_protect(struct kvm *kvm, u64 gfn,
struct kvm_memory_slot *slot)
{
unsigned long *rmapp;
- u64 *spte;
int i, write_protected = 0;
- rmapp = __gfn_to_rmap(gfn, PT_PAGE_TABLE_LEVEL, slot);
- spte = rmap_next(rmapp, NULL);
- while (spte) {
- BUG_ON(!(*spte & PT_PRESENT_MASK));
- rmap_printk("rmap_write_protect: spte %p %llx\n", spte, *spte);
- if (is_writable_pte(*spte)) {
- mmu_spte_update(spte, *spte & ~PT_WRITABLE_MASK);
- write_protected = 1;
- }
- spte = rmap_next(rmapp, spte);
- }
-
- /* check for huge page mappings */
- for (i = PT_DIRECTORY_LEVEL;
+ for (i = PT_PAGE_TABLE_LEVEL;
i < PT_PAGE_TABLE_LEVEL + KVM_NR_PAGE_SIZES; ++i) {
rmapp = __gfn_to_rmap(gfn, i, slot);
- spte = rmap_next(rmapp, NULL);
- while (spte) {
- BUG_ON(!(*spte & PT_PRESENT_MASK));
- BUG_ON(!is_large_pte(*spte));
- pgprintk("rmap_write_protect(large): spte %p %llx %lld\n", spte, *spte, gfn);
- if (is_writable_pte(*spte)) {
- drop_spte(kvm, spte);
- --kvm->stat.lpages;
- spte = NULL;
- write_protected = 1;
- }
- spte = rmap_next(rmapp, spte);
- }
+ write_protected |= __rmap_write_protect(kvm, rmapp, i);
}
return write_protected;