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KVM: MMU: Split the main body of rmap_write_protect() off from others

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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>
This commit is contained in:
Takuya Yoshikawa 2012-03-01 19:31:22 +09:00 committed by Avi Kivity
parent 248997095d
commit a0ed46073c
1 changed files with 29 additions and 28 deletions
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57
arch/x86/kvm/mmu.c
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@ -1010,42 +1010,43 @@ static void drop_spte(struct kvm *kvm, u64 *sptep)
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;