Messages in this thread | | | Subject | Re: [PATCH v6 1/7] s390: ap: kvm: add PQAP interception for AQIC | From | Tony Krowiak <> | Date | Thu, 28 Mar 2019 12:12:10 -0400 |
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On 3/22/19 10:43 AM, Pierre Morel wrote: > We prepare the interception of the PQAP/AQIC instruction for > the case the AQIC facility is enabled in the guest. > > First of all we do not want to change existing behavior when > intercepting AP instructions without the SIE allowing the guest > to use AP instructions. > > In this patch we only handle the AQIC interception allowed by > facility 65 which will be enabled when the complete interception > infrastructure will be present. > > We add a callback inside the KVM arch structure for s390 for > a VFIO driver to handle a specific response to the PQAP > instruction with the AQIC command and only this command. > > But we want to be able to return a correct answer to the guest > even there is no VFIO AP driver in the kernel. > Therefor, we inject the correct exceptions from inside KVM for the > case the callback is not initialized, which happens when the vfio_ap > driver is not loaded. > > We do consider the responsability of the driver to always initialize > the PQAP callback if it defines queues by initializing the CRYCB for > a guest. > If the callback has been setup we call it. > If not we setup an answer considering that no queue is available > for the guest when no callback has been setup. > > Signed-off-by: Pierre Morel <pmorel@linux.ibm.com> > --- > arch/s390/include/asm/kvm_host.h | 8 ++++ > arch/s390/kvm/priv.c | 90 +++++++++++++++++++++++++++++++++++ > drivers/s390/crypto/vfio_ap_private.h | 2 + > 3 files changed, 100 insertions(+) > > diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h > index a496276..624460b 100644 > --- a/arch/s390/include/asm/kvm_host.h > +++ b/arch/s390/include/asm/kvm_host.h > @@ -18,6 +18,7 @@ > #include <linux/kvm_host.h> > #include <linux/kvm.h> > #include <linux/seqlock.h> > +#include <linux/module.h> > #include <asm/debug.h> > #include <asm/cpu.h> > #include <asm/fpu/api.h> > @@ -721,8 +722,15 @@ struct kvm_s390_cpu_model { > unsigned short ibc; > }; > > +struct kvm_s390_module_hook { > + int (*hook)(struct kvm_vcpu *vcpu); > + void *data; > + struct module *owner; > +}; > + > struct kvm_s390_crypto { > struct kvm_s390_crypto_cb *crycb; > + struct kvm_s390_module_hook *pqap_hook; > __u32 crycbd; > __u8 aes_kw; > __u8 dea_kw; > diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c > index 8679bd7..793e48a 100644 > --- a/arch/s390/kvm/priv.c > +++ b/arch/s390/kvm/priv.c > @@ -27,6 +27,7 @@ > #include <asm/io.h> > #include <asm/ptrace.h> > #include <asm/sclp.h> > +#include <asm/ap.h> > #include "gaccess.h" > #include "kvm-s390.h" > #include "trace.h" > @@ -592,6 +593,93 @@ static int handle_io_inst(struct kvm_vcpu *vcpu) > } > } > > +/* > + * handle_pqap: Handling pqap interception > + * @vcpu: the vcpu having issue the pqap instruction > + * > + * We now support PQAP/AQIC instructions and we need to correctly > + * answer the guest even if no dedicated driver's hook is available. > + * > + * The intercepting code calls a dedicated callback for this instruction > + * if a driver did register one in the CRYPTO satellite of the > + * SIE block. > + * > + * For PQAP AQIC and TAPQ instructions, verify privilege and specifications. > + * > + * If no callback available, the queues are not available, return this to > + * the caller. > + * Else return the value returned by the callback. > + */ > +static int handle_pqap(struct kvm_vcpu *vcpu) > +{ > + struct ap_queue_status status = {}; > + unsigned long reg0; > + int ret; > + uint8_t fc; > + > + /* Verify that the AP instruction are available */ > + if (!ap_instructions_available()) > + return -EOPNOTSUPP; > + /* Verify that the guest is allowed to use AP instructions */ > + if (!(vcpu->arch.sie_block->eca & ECA_APIE)) > + return -EOPNOTSUPP; > + /* > + * The only possibly intercepted instructions when AP instructions are > + * available for the guest are AQIC and TAPQ with the t bit set > + * since we do not set IC.3 (FIII) we currently will not intercept > + * TAPQ. > + * The following code will only treat AQIC function code. > + */ > + reg0 = vcpu->run->s.regs.gprs[0]; > + fc = reg0 >> 24; > + if (fc != 0x03) { > + pr_warn("%s: Unexpected interception code 0x%02x\n", > + __func__, fc); > + return -EOPNOTSUPP; > + } > + /* All PQAP instructions are allowed for guest kernel only */ > + if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE) > + return kvm_s390_inject_program_int(vcpu, PGM_PRIVILEGED_OP); > + /* > + * Common tests for PQAP instructions to generate a specification > + * exception > + */ > + /* Zero bits overwrite produce a specification exception */ > + if (reg0 & 0x007f0000UL) > + goto specification_except; > + /* If APXA is not installed APQN is limited */ > + if (!(vcpu->kvm->arch.crypto.crycbd & 0x02)) > + if (reg0 & 0x000030f0UL) > + goto specification_except; > + /* AQIC needs facility 65 */ > + if (!test_kvm_facility(vcpu->kvm, 65)) > + goto specification_except; > + > + /* > + * Verify that the hook callback is registered, lock the owner > + * and call the hook. > + */ > + if (vcpu->kvm->arch.crypto.pqap_hook) { > + if (!try_module_get(vcpu->kvm->arch.crypto.pqap_hook->owner)) > + return -EOPNOTSUPP; > + ret = vcpu->kvm->arch.crypto.pqap_hook->hook(vcpu); > + module_put(vcpu->kvm->arch.crypto.pqap_hook->owner); > + return ret; > + } > + /* > + * It is the duty of the vfio_driver to register a hook > + * If it does not and we get an exception on AQIC we must > + * guess that there is no vfio_ap_driver at all and no one > + * to handle the guests's CRYCB and the CRYCB is empty. > + */ > + status.response_code = 0x01; > + memcpy(&vcpu->run->s.regs.gprs[1], &status, sizeof(status)); > + return 0; > + > +specification_except: > + return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION); > +} > + > static int handle_stfl(struct kvm_vcpu *vcpu) > { > int rc; > @@ -878,6 +966,8 @@ int kvm_s390_handle_b2(struct kvm_vcpu *vcpu) > return handle_sthyi(vcpu); > case 0x7d: > return handle_stsi(vcpu); > + case 0xaf: > + return handle_pqap(vcpu); > case 0xb1: > return handle_stfl(vcpu); > case 0xb2: > diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h > index 76b7f98..a910be1 100644 > --- a/drivers/s390/crypto/vfio_ap_private.h > +++ b/drivers/s390/crypto/vfio_ap_private.h > @@ -16,6 +16,7 @@ > #include <linux/mdev.h> > #include <linux/delay.h> > #include <linux/mutex.h> > +#include <linux/kvm_host.h> > > #include "ap_bus.h" > > @@ -81,6 +82,7 @@ struct ap_matrix_mdev { > struct ap_matrix matrix; > struct notifier_block group_notifier; > struct kvm *kvm; > + struct kvm_s390_module_hook pqap_hook;
I don't understand the purpose of adding this field. We set up the the kvm->arch.crypto.pqap_hook in the vfio_ap_mdev_set_kvm which is also in this same file, why not just use a static struct kvm_s390_module_hook and reuse it when setting up kvm->arch.crypto.pqap_hook? It saves you from initializing it every time an ap_matrix_mdev is created.
> }; > > extern int vfio_ap_mdev_register(void); >
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