Add CLASS() definitions for locally mapping a PFN using kvm_vcpu_map() given a vCPU+gfn pair. In addition to eliminating the need to manually do unmap(), e.g. in error paths, this will allow hardening KVM against double-mapping without having to manually ensure every on-stack declaration is zero-initialized.
Use "map local" as the primary terminology as the basic concept is more or less the same as kmap_local(): ensure the current context has a kernel mapping to the underlying memory. Immediately convert the relatively straightforward nested SVM flows, and defer converting the more involved SMM flows to a separate change. No functional change intended. Cc: Yosry Ahmed <[email protected]> Signed-off-by: Sean Christopherson <[email protected]> --- arch/x86/kvm/svm/nested.c | 18 +++++++----------- arch/x86/kvm/svm/svm.c | 8 +++----- include/linux/kvm_host.h | 19 +++++++++++++++++++ 3 files changed, 29 insertions(+), 16 deletions(-) diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c index 5e3e280cd483..73f37b050d0a 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -1086,14 +1086,14 @@ int enter_svm_guest_mode(struct kvm_vcpu *vcpu, u64 vmcb12_gpa, bool from_vmrun) static int nested_svm_copy_vmcb12_to_cache(struct kvm_vcpu *vcpu, u64 vmcb12_gpa) { struct vcpu_svm *svm = to_svm(vcpu); - struct kvm_host_map map; struct vmcb *vmcb12; int r = 0; - if (kvm_vcpu_map(vcpu, gpa_to_gfn(vmcb12_gpa), &map)) + CLASS(kvm_vcpu_map_local, m)(vcpu, gpa_to_gfn(vmcb12_gpa)); + if (m.ret) return -EFAULT; - vmcb12 = map.hva; + vmcb12 = m.map.hva; nested_copy_vmcb_control_to_cache(svm, &vmcb12->control); nested_copy_vmcb_save_to_cache(svm, &vmcb12->save); @@ -1107,7 +1107,6 @@ static int nested_svm_copy_vmcb12_to_cache(struct kvm_vcpu *vcpu, u64 vmcb12_gpa r = -EINVAL; } - kvm_vcpu_unmap(vcpu, &map); return r; } @@ -1251,15 +1250,13 @@ static int nested_svm_vmexit_update_vmcb12(struct kvm_vcpu *vcpu) { struct vcpu_svm *svm = to_svm(vcpu); struct vmcb *vmcb02 = svm->nested.vmcb02.ptr; - struct kvm_host_map map; struct vmcb *vmcb12; - int rc; - rc = kvm_vcpu_map(vcpu, gpa_to_gfn(svm->nested.vmcb12_gpa), &map); - if (rc) - return rc; + CLASS(kvm_vcpu_map_local, m)(vcpu, gpa_to_gfn(svm->nested.vmcb12_gpa)); + if (m.ret) + return m.ret; - vmcb12 = map.hva; + vmcb12 = m.map.hva; vmcb12->save.es = vmcb02->save.es; vmcb12->save.cs = vmcb02->save.cs; @@ -1314,7 +1311,6 @@ static int nested_svm_vmexit_update_vmcb12(struct kvm_vcpu *vcpu) vmcb12->control.exit_int_info_err, KVM_ISA_SVM); - kvm_vcpu_unmap(vcpu, &map); return 0; } diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 91286d46d13a..bf10483c0e8a 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -2216,7 +2216,6 @@ static int vmload_vmsave_interception(struct kvm_vcpu *vcpu, bool vmload) u64 vmcb12_gpa = kvm_rax_read(vcpu); struct vcpu_svm *svm = to_svm(vcpu); struct vmcb *vmcb12; - struct kvm_host_map map; int ret; if (nested_svm_check_permissions(vcpu)) @@ -2227,10 +2226,11 @@ static int vmload_vmsave_interception(struct kvm_vcpu *vcpu, bool vmload) return 1; } - if (kvm_vcpu_map(vcpu, gpa_to_gfn(vmcb12_gpa), &map)) + CLASS(kvm_vcpu_map_local, m)(vcpu, gpa_to_gfn(vmcb12_gpa)); + if (m.ret) return kvm_handle_memory_failure(vcpu, X86EMUL_IO_NEEDED, NULL); - vmcb12 = map.hva; + vmcb12 = m.map.hva; ret = kvm_skip_emulated_instruction(vcpu); @@ -2243,8 +2243,6 @@ static int vmload_vmsave_interception(struct kvm_vcpu *vcpu, bool vmload) svm_copy_vmloadsave_state(vmcb12, svm->vmcb01.ptr); } - kvm_vcpu_unmap(vcpu, &map); - return ret; } diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 9db6eb4023c4..c54dbfdbc346 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1420,6 +1420,25 @@ static inline void kvm_vcpu_map_mark_dirty(struct kvm_vcpu *vcpu, kvm_vcpu_mark_page_dirty(vcpu, map->gfn); } +typedef struct { + struct kvm_vcpu *vcpu; + struct kvm_host_map map; + int ret; +} kvm_vcpu_local_map_t; + +#define DEFINE_VCPU_MAP_CLASS(ro) \ +DEFINE_CLASS(kvm_vcpu_map_local##ro, kvm_vcpu_local_map_t, \ + if (!_T.ret) kvm_vcpu_unmap(_T.vcpu, &_T.map), \ + ({ \ + kvm_vcpu_local_map_t m = { .vcpu = vcpu }; \ + \ + m.ret = kvm_vcpu_map##ro(vcpu, gfn, &m.map); \ + \ + m; \ + }), struct kvm_vcpu *vcpu, gfn_t gfn); +DEFINE_VCPU_MAP_CLASS(); +DEFINE_VCPU_MAP_CLASS(_readonly); + unsigned long kvm_vcpu_gfn_to_hva(struct kvm_vcpu *vcpu, gfn_t gfn); unsigned long kvm_vcpu_gfn_to_hva_prot(struct kvm_vcpu *vcpu, gfn_t gfn, bool *writable); int kvm_vcpu_read_guest_page(struct kvm_vcpu *vcpu, gfn_t gfn, void *data, int offset, -- 2.55.0.229.g6434b31f56-goog
