[PATCH v4 02/10] KVM: MMU: abstract spte write-protect

Xiao Guangrong
2012-04-25T04:02:01Z

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

Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
---
arch/x86/kvm/mmu.c | 60 ++++++++++++++++++++++++++++++---------------------
1 files changed, 35 insertions(+), 25 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 4a3cc18..e70ff38 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1041,6 +1041,34 @@ 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 large,
+ bool *flush)
+{
+ u64 spte = *sptep;
+
+ if (!is_writable_pte(spte))
+ return false;
+
+ *flush |= true;
+
+ if (large) {
+ pgprintk("rmap_write_protect(large): spte %p %llx\n",
+ spte, *spte);
+ BUG_ON(!is_large_pte(spte));
+
+ drop_spte(kvm, sptep);
+ --kvm->stat.lpages;
+ return true;
+ }
+
+ rmap_printk("rmap_write_protect: spte %p %llx\n", spte, *spte);
+ 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)
{
@@ -1050,24 +1078,13 @@ __rmap_write_protect(struct kvm *kvm, unsigned long *rmapp, int level)

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);
- 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;
+ if (spte_write_protect(kvm, sptep, level > PT_PAGE_TABLE_LEVEL,
+ &write_protected)) {
sptep = rmap_get_first(*rmapp, &iter);
+ continue;
}

- write_protected = true;
+ sptep = rmap_get_next(&iter);
}

return write_protected;
@@ -3902,6 +3919,7 @@ 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;
@@ -3916,16 +3934,8 @@ 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],
+ is_large_pte(pt[i]), &flush);
}
}
kvm_flush_remote_tlbs(kvm);
--
1.7.7.6