From 781e0743af3c5ba356d55bc60df59f2dded1e938 Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Sun, 24 Apr 2011 12:25:50 +0300 Subject: [PATCH] KVM: MMU: Add unlikely() annotations to walk_addr_generic() walk_addr_generic() is a hot path and is also hard for the cpu to predict - some of the parameters (fetch_fault in particular) vary wildly from invocation to invocation. Add unlikely() annotations where appropriate; all walk failures are considered unlikely, as are cases where we have to mark the accessed or dirty bit, as they are slow paths both in kvm and on real processors. Signed-off-by: Avi Kivity --- arch/x86/kvm/paging_tmpl.h | 28 +++++++++++++++------------- 1 file changed, 15 insertions(+), 13 deletions(-) diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h index a32a1c809149..652d56c081f7 100644 --- a/arch/x86/kvm/paging_tmpl.h +++ b/arch/x86/kvm/paging_tmpl.h @@ -172,49 +172,51 @@ walk: real_gfn = mmu->translate_gpa(vcpu, gfn_to_gpa(table_gfn), PFERR_USER_MASK|PFERR_WRITE_MASK); - if (real_gfn == UNMAPPED_GVA) { + if (unlikely(real_gfn == UNMAPPED_GVA)) { present = false; break; } real_gfn = gpa_to_gfn(real_gfn); host_addr = gfn_to_hva(vcpu->kvm, real_gfn); - if (kvm_is_error_hva(host_addr)) { + if (unlikely(kvm_is_error_hva(host_addr))) { present = false; break; } ptep_user = (pt_element_t __user *)((void *)host_addr + offset); - if (get_user(pte, ptep_user)) { + if (unlikely(get_user(pte, ptep_user))) { present = false; break; } trace_kvm_mmu_paging_element(pte, walker->level); - if (!is_present_gpte(pte)) { + if (unlikely(!is_present_gpte(pte))) { present = false; break; } - if (is_rsvd_bits_set(&vcpu->arch.mmu, pte, walker->level)) { + if (unlikely(is_rsvd_bits_set(&vcpu->arch.mmu, pte, + walker->level))) { rsvd_fault = true; break; } - if (write_fault && !is_writable_pte(pte)) - if (user_fault || is_write_protection(vcpu)) - eperm = true; + if (unlikely(write_fault && !is_writable_pte(pte) + && (user_fault || is_write_protection(vcpu)))) + eperm = true; - if (user_fault && !(pte & PT_USER_MASK)) + if (unlikely(user_fault && !(pte & PT_USER_MASK))) eperm = true; #if PTTYPE == 64 - if (fetch_fault && (pte & PT64_NX_MASK)) + if (unlikely(fetch_fault && (pte & PT64_NX_MASK))) eperm = true; #endif - if (!eperm && !rsvd_fault && !(pte & PT_ACCESSED_MASK)) { + if (!eperm && !rsvd_fault + && unlikely(!(pte & PT_ACCESSED_MASK))) { int ret; trace_kvm_mmu_set_accessed_bit(table_gfn, index, sizeof(pte)); @@ -270,10 +272,10 @@ walk: --walker->level; } - if (!present || eperm || rsvd_fault) + if (unlikely(!present || eperm || rsvd_fault)) goto error; - if (write_fault && !is_dirty_gpte(pte)) { + if (write_fault && unlikely(!is_dirty_gpte(pte))) { int ret; trace_kvm_mmu_set_dirty_bit(table_gfn, index, sizeof(pte)); -- 2.20.1