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Subject[PATCH 1/4] 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>
---
arch/x86/kvm/mmu.c | 53 ++++++++++++++++++++++++++-------------------------
1 files changed, 27 insertions(+), 26 deletions(-)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index ff053ca..67857bd 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1010,42 +1010,43 @@ static void drop_spte(struct kvm *kvm, u64 *sptep)
rmap_remove(kvm, sptep);
}

-int kvm_mmu_rmap_write_protect(struct kvm *kvm, u64 gfn,
- struct kvm_memory_slot *slot)
+static int __rmap_write_protect(struct kvm *kvm, unsigned long *rmapp, int level)
{
- unsigned long *rmapp;
- u64 *spte;
- int i, write_protected = 0;
+ u64 *spte = NULL;
+ int write_protected = 0;

- rmapp = __gfn_to_rmap(gfn, PT_PAGE_TABLE_LEVEL, slot);
- spte = rmap_next(rmapp, NULL);
- while (spte) {
+ 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)) {
+
+ if (!is_writable_pte(*spte))
+ continue;
+
+ if (level == PT_PAGE_TABLE_LEVEL) {
mmu_spte_update(spte, *spte & ~PT_WRITABLE_MASK);
- write_protected = 1;
+ } else {
+ BUG_ON(!is_large_pte(*spte));
+ drop_spte(kvm, spte);
+ --kvm->stat.lpages;
+ spte = NULL;
}
- spte = rmap_next(rmapp, spte);
+
+ write_protected = 1;
}

- /* check for huge page mappings */
- for (i = PT_DIRECTORY_LEVEL;
+ return write_protected;
+}
+
+int kvm_mmu_rmap_write_protect(struct kvm *kvm, u64 gfn,
+ struct kvm_memory_slot *slot)
+{
+ unsigned long *rmapp;
+ int i, write_protected = 0;
+
+ 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;
--
1.7.5.4


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