diff options
| -rw-r--r-- | drivers/kvm/kvm.h | 3 | ||||
| -rw-r--r-- | drivers/kvm/mmu.c | 16 |
2 files changed, 18 insertions, 1 deletions
diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h index 6e4daf40414..201b2735ca9 100644 --- a/drivers/kvm/kvm.h +++ b/drivers/kvm/kvm.h @@ -238,6 +238,9 @@ struct kvm_vcpu { struct kvm_mmu_page page_header_buf[KVM_NUM_MMU_PAGES]; struct kvm_mmu mmu; + gfn_t last_pt_write_gfn; + int last_pt_write_count; + struct kvm_guest_debug guest_debug; char fx_buf[FX_BUF_SIZE]; diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c index 8cf3688f7e7..0e44aca9eee 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); |