| Message ID | 20200520165110.71020-1-ldufour@linux.ibm.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | KVM: PPC: Book3S HV: relax check on H_SVM_INIT_ABORT | expand |
On Wed, 20 May 2020 18:51:10 +0200 Laurent Dufour <ldufour@linux.ibm.com> wrote: > The commit 8c47b6ff29e3 ("KVM: PPC: Book3S HV: Check caller of H_SVM_* > Hcalls") added checks of secure bit of SRR1 to filter out the Hcall > reserved to the Ultravisor. > > However, the Hcall H_SVM_INIT_ABORT is made by the Ultravisor passing the > context of the VM calling UV_ESM. This allows the Hypervisor to return to > the guest without going through the Ultravisor. Thus the Secure bit of SRR1 > is not set in that particular case. > > In the case a regular VM is calling H_SVM_INIT_ABORT, this hcall will be > filtered out in kvmppc_h_svm_init_abort() because kvm->arch.secure_guest is > not set in that case. > Why not checking vcpu->kvm->arch.secure_guest then ? > Fixes: 8c47b6ff29e3 ("KVM: PPC: Book3S HV: Check caller of H_SVM_* Hcalls") > Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com> > --- > arch/powerpc/kvm/book3s_hv.c | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c > index 93493f0cbfe8..eb1f96cb7b72 100644 > --- a/arch/powerpc/kvm/book3s_hv.c > +++ b/arch/powerpc/kvm/book3s_hv.c > @@ -1099,9 +1099,7 @@ int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu) > ret = kvmppc_h_svm_init_done(vcpu->kvm); > break; > case H_SVM_INIT_ABORT: > - ret = H_UNSUPPORTED; > - if (kvmppc_get_srr1(vcpu) & MSR_S) > - ret = kvmppc_h_svm_init_abort(vcpu->kvm); or at least put a comment to explain why H_SVM_INIT_ABORT doesn't have the same sanity check as the other SVM hcalls. > + ret = kvmppc_h_svm_init_abort(vcpu->kvm); > break; > > default:
Le 20/05/2020 à 19:32, Greg Kurz a écrit : > On Wed, 20 May 2020 18:51:10 +0200 > Laurent Dufour <ldufour@linux.ibm.com> wrote: > >> The commit 8c47b6ff29e3 ("KVM: PPC: Book3S HV: Check caller of H_SVM_* >> Hcalls") added checks of secure bit of SRR1 to filter out the Hcall >> reserved to the Ultravisor. >> >> However, the Hcall H_SVM_INIT_ABORT is made by the Ultravisor passing the >> context of the VM calling UV_ESM. This allows the Hypervisor to return to >> the guest without going through the Ultravisor. Thus the Secure bit of SRR1 >> is not set in that particular case. >> >> In the case a regular VM is calling H_SVM_INIT_ABORT, this hcall will be >> filtered out in kvmppc_h_svm_init_abort() because kvm->arch.secure_guest is >> not set in that case. >> > > Why not checking vcpu->kvm->arch.secure_guest then ? I don't think that's the right place. > >> Fixes: 8c47b6ff29e3 ("KVM: PPC: Book3S HV: Check caller of H_SVM_* Hcalls") >> Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com> >> --- >> arch/powerpc/kvm/book3s_hv.c | 4 +--- >> 1 file changed, 1 insertion(+), 3 deletions(-) >> >> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c >> index 93493f0cbfe8..eb1f96cb7b72 100644 >> --- a/arch/powerpc/kvm/book3s_hv.c >> +++ b/arch/powerpc/kvm/book3s_hv.c >> @@ -1099,9 +1099,7 @@ int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu) >> ret = kvmppc_h_svm_init_done(vcpu->kvm); >> break; >> case H_SVM_INIT_ABORT: >> - ret = H_UNSUPPORTED; >> - if (kvmppc_get_srr1(vcpu) & MSR_S) >> - ret = kvmppc_h_svm_init_abort(vcpu->kvm); > > or at least put a comment to explain why H_SVM_INIT_ABORT > doesn't have the same sanity check as the other SVM hcalls. I agree that might help. I'll send a v2 with a comment there. > >> + ret = kvmppc_h_svm_init_abort(vcpu->kvm); >> break; >> >> default: >
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 93493f0cbfe8..eb1f96cb7b72 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -1099,9 +1099,7 @@ int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu) ret = kvmppc_h_svm_init_done(vcpu->kvm); break; case H_SVM_INIT_ABORT: - ret = H_UNSUPPORTED; - if (kvmppc_get_srr1(vcpu) & MSR_S) - ret = kvmppc_h_svm_init_abort(vcpu->kvm); + ret = kvmppc_h_svm_init_abort(vcpu->kvm); break; default:
The commit 8c47b6ff29e3 ("KVM: PPC: Book3S HV: Check caller of H_SVM_* Hcalls") added checks of secure bit of SRR1 to filter out the Hcall reserved to the Ultravisor. However, the Hcall H_SVM_INIT_ABORT is made by the Ultravisor passing the context of the VM calling UV_ESM. This allows the Hypervisor to return to the guest without going through the Ultravisor. Thus the Secure bit of SRR1 is not set in that particular case. In the case a regular VM is calling H_SVM_INIT_ABORT, this hcall will be filtered out in kvmppc_h_svm_init_abort() because kvm->arch.secure_guest is not set in that case. Fixes: 8c47b6ff29e3 ("KVM: PPC: Book3S HV: Check caller of H_SVM_* Hcalls") Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com> --- arch/powerpc/kvm/book3s_hv.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)