diff options
Diffstat (limited to 'drivers/kvm/mmu.c')
| -rw-r--r-- | drivers/kvm/mmu.c | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c index 8cf3688f7e70..0e44aca9eee7 100644 --- a/drivers/kvm/mmu.c +++ b/drivers/kvm/mmu.c @@ -969,8 +969,17 @@ void kvm_mmu_pre_write(struct kvm_vcpu *vcpu, gpa_t gpa, int bytes) unsigned page_offset; unsigned misaligned; int level; + int flooded = 0; pgprintk("%s: gpa %llx bytes %d\n", __FUNCTION__, gpa, bytes); + if (gfn == vcpu->last_pt_write_gfn) { + ++vcpu->last_pt_write_count; + if (vcpu->last_pt_write_count >= 3) + flooded = 1; + } else { + vcpu->last_pt_write_gfn = gfn; + vcpu->last_pt_write_count = 1; + } index = kvm_page_table_hashfn(gfn) % KVM_NUM_MMU_PAGES; bucket = &vcpu->kvm->mmu_page_hash[index]; hlist_for_each_entry_safe(page, node, n, bucket, hash_link) { @@ -978,11 +987,16 @@ void kvm_mmu_pre_write(struct kvm_vcpu *vcpu, gpa_t gpa, int bytes) continue; pte_size = page->role.glevels == PT32_ROOT_LEVEL ? 4 : 8; misaligned = (offset ^ (offset + bytes - 1)) & ~(pte_size - 1); - if (misaligned) { + if (misaligned || flooded) { /* * Misaligned accesses are too much trouble to fix * up; also, they usually indicate a page is not used * as a page table. + * + * If we're seeing too many writes to a page, + * it may no longer be a page table, or we may be + * forking, in which case it is better to unmap the + * page. */ pgprintk("misaligned: gpa %llx bytes %d role %x\n", gpa, bytes, page->role.word); |