| Message ID | 20110620232947.83d016d3.takuya.yoshikawa@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Jun 20, 2011 at 11:29:47PM +0900, Takuya Yoshikawa wrote: > From: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp> > > Avoid two step jump to the error handling part. This eliminates the use > of the variables present and rsvd_fault. > > We also use the const type qualifier to show that write/user/fetch_fault > do not change in the function. > > Both of these were suggested by Ingo Molnar. > > Cc: Ingo Molnar <mingo@elte.hu> > Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp> > --- > v2-v3: only changelog update > > arch/x86/kvm/paging_tmpl.h | 64 +++++++++++++++++++------------------------ > 1 files changed, 28 insertions(+), 36 deletions(-) > > diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h > index 1caeb4d..137aa45 100644 > --- a/arch/x86/kvm/paging_tmpl.h > +++ b/arch/x86/kvm/paging_tmpl.h > @@ -125,18 +125,17 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker, > gfn_t table_gfn; > unsigned index, pt_access, uninitialized_var(pte_access); > gpa_t pte_gpa; > - bool eperm, present, rsvd_fault; > - int offset, write_fault, user_fault, fetch_fault; > - > - write_fault = access & PFERR_WRITE_MASK; > - user_fault = access & PFERR_USER_MASK; > - fetch_fault = access & PFERR_FETCH_MASK; > + bool eperm; > + int offset; > + const int write_fault = access & PFERR_WRITE_MASK; > + const int user_fault = access & PFERR_USER_MASK; > + const int fetch_fault = access & PFERR_FETCH_MASK; > + u16 errcode = 0; > > trace_kvm_mmu_pagetable_walk(addr, write_fault, user_fault, > fetch_fault); > walk: > - present = true; > - eperm = rsvd_fault = false; > + eperm = false; > walker->level = mmu->root_level; > pte = mmu->get_cr3(vcpu); > > @@ -145,7 +144,7 @@ walk: > pte = kvm_pdptr_read_mmu(vcpu, mmu, (addr >> 30) & 3); > trace_kvm_mmu_paging_element(pte, walker->level); > if (!is_present_gpte(pte)) { > - present = false; > + errcode |= PFERR_PRESENT_MASK; > goto error; > } > --walker->level; > @@ -171,34 +170,34 @@ walk: > real_gfn = mmu->translate_gpa(vcpu, gfn_to_gpa(table_gfn), > PFERR_USER_MASK|PFERR_WRITE_MASK); > if (unlikely(real_gfn == UNMAPPED_GVA)) { > - present = false; > - break; > + errcode |= PFERR_PRESENT_MASK; > + goto error; > } > real_gfn = gpa_to_gfn(real_gfn); > > host_addr = gfn_to_hva(vcpu->kvm, real_gfn); > if (unlikely(kvm_is_error_hva(host_addr))) { > - present = false; > - break; > + errcode |= PFERR_PRESENT_MASK; > + goto error; > } > > ptep_user = (pt_element_t __user *)((void *)host_addr + offset); > if (unlikely(__copy_from_user(&pte, ptep_user, sizeof(pte)))) { > - present = false; > - break; > + errcode |= PFERR_PRESENT_MASK; > + goto error; > } > > trace_kvm_mmu_paging_element(pte, walker->level); > > if (unlikely(!is_present_gpte(pte))) { > - present = false; > - break; > + errcode |= PFERR_PRESENT_MASK; > + goto error; > } Assignment of PFERR_PRESENT_MASK is inverted. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 06/22/2011 07:46 PM, Marcelo Tosatti wrote: > > if (unlikely(!is_present_gpte(pte))) { > > - present = false; > > - break; > > + errcode |= PFERR_PRESENT_MASK; > > + goto error; > > } > > Assignment of PFERR_PRESENT_MASK is inverted. > Note: kvm-unit-tests.git/x86/access.flat would have caught this.
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h index 1caeb4d..137aa45 100644 --- a/arch/x86/kvm/paging_tmpl.h +++ b/arch/x86/kvm/paging_tmpl.h @@ -125,18 +125,17 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker, gfn_t table_gfn; unsigned index, pt_access, uninitialized_var(pte_access); gpa_t pte_gpa; - bool eperm, present, rsvd_fault; - int offset, write_fault, user_fault, fetch_fault; - - write_fault = access & PFERR_WRITE_MASK; - user_fault = access & PFERR_USER_MASK; - fetch_fault = access & PFERR_FETCH_MASK; + bool eperm; + int offset; + const int write_fault = access & PFERR_WRITE_MASK; + const int user_fault = access & PFERR_USER_MASK; + const int fetch_fault = access & PFERR_FETCH_MASK; + u16 errcode = 0; trace_kvm_mmu_pagetable_walk(addr, write_fault, user_fault, fetch_fault); walk: - present = true; - eperm = rsvd_fault = false; + eperm = false; walker->level = mmu->root_level; pte = mmu->get_cr3(vcpu); @@ -145,7 +144,7 @@ walk: pte = kvm_pdptr_read_mmu(vcpu, mmu, (addr >> 30) & 3); trace_kvm_mmu_paging_element(pte, walker->level); if (!is_present_gpte(pte)) { - present = false; + errcode |= PFERR_PRESENT_MASK; goto error; } --walker->level; @@ -171,34 +170,34 @@ walk: real_gfn = mmu->translate_gpa(vcpu, gfn_to_gpa(table_gfn), PFERR_USER_MASK|PFERR_WRITE_MASK); if (unlikely(real_gfn == UNMAPPED_GVA)) { - present = false; - break; + errcode |= PFERR_PRESENT_MASK; + goto error; } real_gfn = gpa_to_gfn(real_gfn); host_addr = gfn_to_hva(vcpu->kvm, real_gfn); if (unlikely(kvm_is_error_hva(host_addr))) { - present = false; - break; + errcode |= PFERR_PRESENT_MASK; + goto error; } ptep_user = (pt_element_t __user *)((void *)host_addr + offset); if (unlikely(__copy_from_user(&pte, ptep_user, sizeof(pte)))) { - present = false; - break; + errcode |= PFERR_PRESENT_MASK; + goto error; } trace_kvm_mmu_paging_element(pte, walker->level); if (unlikely(!is_present_gpte(pte))) { - present = false; - break; + errcode |= PFERR_PRESENT_MASK; + goto error; } if (unlikely(is_rsvd_bits_set(&vcpu->arch.mmu, pte, walker->level))) { - rsvd_fault = true; - break; + errcode |= PFERR_RSVD_MASK; + goto error; } if (unlikely(write_fault && !is_writable_pte(pte) @@ -213,16 +212,15 @@ walk: eperm = true; #endif - if (!eperm && !rsvd_fault - && unlikely(!(pte & PT_ACCESSED_MASK))) { + if (!eperm && unlikely(!(pte & PT_ACCESSED_MASK))) { int ret; trace_kvm_mmu_set_accessed_bit(table_gfn, index, sizeof(pte)); ret = FNAME(cmpxchg_gpte)(vcpu, mmu, ptep_user, index, pte, pte|PT_ACCESSED_MASK); if (unlikely(ret < 0)) { - present = false; - break; + errcode |= PFERR_PRESENT_MASK; + goto error; } else if (ret) goto walk; @@ -276,7 +274,7 @@ walk: --walker->level; } - if (unlikely(!present || eperm || rsvd_fault)) + if (unlikely(eperm)) goto error; if (write_fault && unlikely(!is_dirty_gpte(pte))) { @@ -286,7 +284,7 @@ walk: ret = FNAME(cmpxchg_gpte)(vcpu, mmu, ptep_user, index, pte, pte|PT_DIRTY_MASK); if (unlikely(ret < 0)) { - present = false; + errcode |= PFERR_PRESENT_MASK; goto error; } else if (ret) goto walk; @@ -303,20 +301,14 @@ walk: return 1; error: - walker->fault.vector = PF_VECTOR; - walker->fault.error_code_valid = true; - walker->fault.error_code = 0; - if (present) - walker->fault.error_code |= PFERR_PRESENT_MASK; - - walker->fault.error_code |= write_fault | user_fault; - + errcode |= write_fault | user_fault; if (fetch_fault && (mmu->nx || kvm_read_cr4_bits(vcpu, X86_CR4_SMEP))) - walker->fault.error_code |= PFERR_FETCH_MASK; - if (rsvd_fault) - walker->fault.error_code |= PFERR_RSVD_MASK; + errcode |= PFERR_FETCH_MASK; + walker->fault.vector = PF_VECTOR; + walker->fault.error_code_valid = true; + walker->fault.error_code = errcode; walker->fault.address = addr; walker->fault.nested_page_fault = mmu != vcpu->arch.walk_mmu;