| Message ID | 20180830031647.34134-5-aik@ozlabs.ru |
|---|---|
| State | Superseded |
| Headers | show |
| Series | KVM: PPC: Some error handling rework | expand |
On Thu, Aug 30, 2018 at 01:16:47PM +1000, Alexey Kardashevskiy wrote: > At the moment if the PUT_TCE{_INDIRECT} handlers fail to update > the hardware tables, we print a warning once, clear the entry and > continue. This is so as at the time the assumption was that if > a VFIO device is hotplugged into the guest, and the userspace replays > virtual DMA mappings (i.e. TCEs) to the hardware tables and if this fails, > then there is nothing useful we can do about it. > > However the assumption is not valid as these handlers are not called for > TCE replay (VFIO ioctl interface is used for that) and these handlers > are for new TCEs. > > This returns an error to the guest if there is a request which cannot be > processed. By now the only possible failure must be H_TOO_HARD. > > Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> Reviewed-by: David Gibson <david@gibson.dropbear.id.au> > --- > arch/powerpc/kvm/book3s_64_vio.c | 20 ++++++-------------- > arch/powerpc/kvm/book3s_64_vio_hv.c | 20 ++++++-------------- > 2 files changed, 12 insertions(+), 28 deletions(-) > > diff --git a/arch/powerpc/kvm/book3s_64_vio.c b/arch/powerpc/kvm/book3s_64_vio.c > index 5cd2a66..5e3151b 100644 > --- a/arch/powerpc/kvm/book3s_64_vio.c > +++ b/arch/powerpc/kvm/book3s_64_vio.c > @@ -568,14 +568,10 @@ long kvmppc_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn, > ret = kvmppc_tce_iommu_map(vcpu->kvm, stt, stit->tbl, > entry, ua, dir); > > - if (ret == H_SUCCESS) > - continue; > - > - if (ret == H_TOO_HARD) > + if (ret != H_SUCCESS) { > + kvmppc_clear_tce(stit->tbl, entry); > goto unlock_exit; > - > - WARN_ON_ONCE(1); > - kvmppc_clear_tce(stit->tbl, entry); > + } > } > > kvmppc_tce_put(stt, entry, tce); > @@ -660,14 +656,10 @@ long kvmppc_h_put_tce_indirect(struct kvm_vcpu *vcpu, > stit->tbl, entry + i, ua, > iommu_tce_direction(tce)); > > - if (ret == H_SUCCESS) > - continue; > - > - if (ret == H_TOO_HARD) > + if (ret != H_SUCCESS) { > + kvmppc_clear_tce(stit->tbl, entry); > goto unlock_exit; > - > - WARN_ON_ONCE(1); > - kvmppc_clear_tce(stit->tbl, entry); > + } > } > > kvmppc_tce_put(stt, entry + i, tce); > diff --git a/arch/powerpc/kvm/book3s_64_vio_hv.c b/arch/powerpc/kvm/book3s_64_vio_hv.c > index e79ffbb..8d82133 100644 > --- a/arch/powerpc/kvm/book3s_64_vio_hv.c > +++ b/arch/powerpc/kvm/book3s_64_vio_hv.c > @@ -380,14 +380,10 @@ long kvmppc_rm_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn, > ret = kvmppc_rm_tce_iommu_map(vcpu->kvm, stt, > stit->tbl, entry, ua, dir); > > - if (ret == H_SUCCESS) > - continue; > - > - if (ret == H_TOO_HARD) > + if (ret != H_SUCCESS) { > + kvmppc_rm_clear_tce(stit->tbl, entry); > return ret; > - > - WARN_ON_ONCE_RM(1); > - kvmppc_rm_clear_tce(stit->tbl, entry); > + } > } > > kvmppc_tce_put(stt, entry, tce); > @@ -533,14 +529,10 @@ long kvmppc_rm_h_put_tce_indirect(struct kvm_vcpu *vcpu, > stit->tbl, entry + i, ua, > iommu_tce_direction(tce)); > > - if (ret == H_SUCCESS) > - continue; > - > - if (ret == H_TOO_HARD) > + if (ret != H_SUCCESS) { > + kvmppc_rm_clear_tce(stit->tbl, entry); > goto unlock_exit; > - > - WARN_ON_ONCE_RM(1); > - kvmppc_rm_clear_tce(stit->tbl, entry); > + } > } > > kvmppc_tce_put(stt, entry + i, tce);
diff --git a/arch/powerpc/kvm/book3s_64_vio.c b/arch/powerpc/kvm/book3s_64_vio.c index 5cd2a66..5e3151b 100644 --- a/arch/powerpc/kvm/book3s_64_vio.c +++ b/arch/powerpc/kvm/book3s_64_vio.c @@ -568,14 +568,10 @@ long kvmppc_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn, ret = kvmppc_tce_iommu_map(vcpu->kvm, stt, stit->tbl, entry, ua, dir); - if (ret == H_SUCCESS) - continue; - - if (ret == H_TOO_HARD) + if (ret != H_SUCCESS) { + kvmppc_clear_tce(stit->tbl, entry); goto unlock_exit; - - WARN_ON_ONCE(1); - kvmppc_clear_tce(stit->tbl, entry); + } } kvmppc_tce_put(stt, entry, tce); @@ -660,14 +656,10 @@ long kvmppc_h_put_tce_indirect(struct kvm_vcpu *vcpu, stit->tbl, entry + i, ua, iommu_tce_direction(tce)); - if (ret == H_SUCCESS) - continue; - - if (ret == H_TOO_HARD) + if (ret != H_SUCCESS) { + kvmppc_clear_tce(stit->tbl, entry); goto unlock_exit; - - WARN_ON_ONCE(1); - kvmppc_clear_tce(stit->tbl, entry); + } } kvmppc_tce_put(stt, entry + i, tce); diff --git a/arch/powerpc/kvm/book3s_64_vio_hv.c b/arch/powerpc/kvm/book3s_64_vio_hv.c index e79ffbb..8d82133 100644 --- a/arch/powerpc/kvm/book3s_64_vio_hv.c +++ b/arch/powerpc/kvm/book3s_64_vio_hv.c @@ -380,14 +380,10 @@ long kvmppc_rm_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn, ret = kvmppc_rm_tce_iommu_map(vcpu->kvm, stt, stit->tbl, entry, ua, dir); - if (ret == H_SUCCESS) - continue; - - if (ret == H_TOO_HARD) + if (ret != H_SUCCESS) { + kvmppc_rm_clear_tce(stit->tbl, entry); return ret; - - WARN_ON_ONCE_RM(1); - kvmppc_rm_clear_tce(stit->tbl, entry); + } } kvmppc_tce_put(stt, entry, tce); @@ -533,14 +529,10 @@ long kvmppc_rm_h_put_tce_indirect(struct kvm_vcpu *vcpu, stit->tbl, entry + i, ua, iommu_tce_direction(tce)); - if (ret == H_SUCCESS) - continue; - - if (ret == H_TOO_HARD) + if (ret != H_SUCCESS) { + kvmppc_rm_clear_tce(stit->tbl, entry); goto unlock_exit; - - WARN_ON_ONCE_RM(1); - kvmppc_rm_clear_tce(stit->tbl, entry); + } } kvmppc_tce_put(stt, entry + i, tce);
At the moment if the PUT_TCE{_INDIRECT} handlers fail to update the hardware tables, we print a warning once, clear the entry and continue. This is so as at the time the assumption was that if a VFIO device is hotplugged into the guest, and the userspace replays virtual DMA mappings (i.e. TCEs) to the hardware tables and if this fails, then there is nothing useful we can do about it. However the assumption is not valid as these handlers are not called for TCE replay (VFIO ioctl interface is used for that) and these handlers are for new TCEs. This returns an error to the guest if there is a request which cannot be processed. By now the only possible failure must be H_TOO_HARD. Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> --- arch/powerpc/kvm/book3s_64_vio.c | 20 ++++++-------------- arch/powerpc/kvm/book3s_64_vio_hv.c | 20 ++++++-------------- 2 files changed, 12 insertions(+), 28 deletions(-)