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KVM: MMU: abstract spte write-protect 

Introduce a common function to abstract spte write-protect to
cleanup the code

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 2012-06-20 15:57:15 +08:00 committed by Avi Kivity
parent 2f84569f97
commit d13bc5b5a1
1 changed files with 31 additions and 27 deletions
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58
arch/x86/kvm/mmu.c
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@ -1050,36 +1050,48 @@ static void drop_spte(struct kvm *kvm, u64 *sptep)
rmap_remove(kvm, sptep);
}
/* Return true if the spte is dropped. */
static bool spte_write_protect(struct kvm *kvm, u64 *sptep, bool *flush)
{
u64 spte = *sptep;
if (!is_writable_pte(spte))
return false;
rmap_printk("rmap_write_protect: spte %p %llx\n", sptep, *sptep);
*flush |= true;
if (is_large_pte(spte)) {
WARN_ON(page_header(__pa(sptep))->role.level ==
PT_PAGE_TABLE_LEVEL);
drop_spte(kvm, sptep);
--kvm->stat.lpages;
return true;
}
spte = spte & ~PT_WRITABLE_MASK;
mmu_spte_update(sptep, spte);
return false;
}
static bool
__rmap_write_protect(struct kvm *kvm, unsigned long *rmapp, int level)
{
u64 *sptep;
struct rmap_iterator iter;
bool write_protected = false;
bool flush = false;
for (sptep = rmap_get_first(*rmapp, &iter); sptep;) {
BUG_ON(!(*sptep & PT_PRESENT_MASK));
rmap_printk("rmap_write_protect: spte %p %llx\n", sptep, *sptep);
if (!is_writable_pte(*sptep)) {
sptep = rmap_get_next(&iter);
if (spte_write_protect(kvm, sptep, &flush)) {
sptep = rmap_get_first(*rmapp, &iter);
continue;
}
if (level == PT_PAGE_TABLE_LEVEL) {
mmu_spte_update(sptep, *sptep & ~PT_WRITABLE_MASK);
sptep = rmap_get_next(&iter);
} else {
BUG_ON(!is_large_pte(*sptep));
drop_spte(kvm, sptep);
--kvm->stat.lpages;
sptep = rmap_get_first(*rmapp, &iter);
}
write_protected = true;
sptep = rmap_get_next(&iter);
}
return write_protected;
return flush;
}
/**
@ -3886,6 +3898,7 @@ int kvm_mmu_setup(struct kvm_vcpu *vcpu)
void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot)
{
struct kvm_mmu_page *sp;
bool flush = false;
list_for_each_entry(sp, &kvm->arch.active_mmu_pages, link) {
int i;
@ -3900,16 +3913,7 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot)
!is_last_spte(pt[i], sp->role.level))
continue;
if (is_large_pte(pt[i])) {
drop_spte(kvm, &pt[i]);
--kvm->stat.lpages;
continue;
}
/* avoid RMW */
if (is_writable_pte(pt[i]))
mmu_spte_update(&pt[i],
pt[i] & ~PT_WRITABLE_MASK);
spte_write_protect(kvm, &pt[i], &flush);
}
}
kvm_flush_remote_tlbs(kvm);