Messages in this thread | | | Subject | Re: [PATCH v4 13/15] KVM: s390: configure the guest's AP devices | From | Tony Krowiak <> | Date | Tue, 17 Apr 2018 12:08:53 -0400 |
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On 04/16/2018 09:05 AM, Pierre Morel wrote: > On 15/04/2018 23:22, Tony Krowiak wrote: >> Registers a group notifier during the open of the mediated >> matrix device to get information on KVM presence through the >> VFIO_GROUP_NOTIFY_SET_KVM event. When notified, the pointer >> to the kvm structure is saved inside the mediated matrix >> device. Once the VFIO AP device driver has access to KVM, >> access to the APs can be configured for the guest. >> >> Access to APs is configured when the file descriptor for the >> mediated matrix device is opened by userspace. The items to be >> configured are: >> >> 1. The ECA.28 bit in the SIE state description determines whether >> AP instructions are interpreted by the hardware or intercepted. >> The VFIO AP device driver relies interpretive execution of >> AP instructions so the ECA.28 bit will be set >> >> 2. Guest access to AP adapters, usage domains and control domains >> is controlled by three bit masks referenced from the >> Crypto Control Block (CRYCB) referenced from the guest's SIE state >> description: >> >> * The AP Mask (APM) controls access to the AP adapters. Each bit >> in the APM represents an adapter number - from most significant >> to least significant bit - from 0 to 255. The bits in the APM >> are set according to the adapter numbers assigned to the mediated >> matrix device via its 'assign_adapter' sysfs attribute file. >> >> * The AP Queue (AQM) controls access to the AP queues. Each bit >> in the AQM represents an AP queue index - from most significant >> to least significant bit - from 0 to 255. A queue index references >> a specific domain and is synonymous with the domian number. The >> bits in the AQM are set according to the domain numbers assigned >> to the mediated matrix device via its 'assign_domain' sysfs >> attribute file. >> >> * The AP Domain Mask (ADM) controls access to the AP control >> domains. >> Each bit in the ADM represents a control domain - from most >> significant to least significant bit - from 0-255. The >> bits in the ADM are set according to the domain numbers assigned >> to the mediated matrix device via its 'assign_control_domain' >> sysfs attribute file. >> >> Signed-off-by: Tony Krowiak <akrowiak@linux.vnet.ibm.com> >> --- >> drivers/s390/crypto/vfio_ap_ops.c | 50 >> +++++++++++++++++++++++++++++++++ >> drivers/s390/crypto/vfio_ap_private.h | 2 + >> 2 files changed, 52 insertions(+), 0 deletions(-) >> >> diff --git a/drivers/s390/crypto/vfio_ap_ops.c >> b/drivers/s390/crypto/vfio_ap_ops.c >> index bc2b05e..e3ff5ab 100644 >> --- a/drivers/s390/crypto/vfio_ap_ops.c >> +++ b/drivers/s390/crypto/vfio_ap_ops.c >> @@ -53,6 +53,54 @@ static int vfio_ap_mdev_remove(struct mdev_device >> *mdev) >> return 0; >> } >> >> +static int vfio_ap_mdev_group_notifier(struct notifier_block *nb, >> + unsigned long action, void *data) >> +{ >> + struct ap_matrix_mdev *matrix_mdev; >> + >> + if (action == VFIO_GROUP_NOTIFY_SET_KVM) { >> + matrix_mdev = container_of(nb, struct ap_matrix_mdev, >> + group_notifier); >> + matrix_mdev->kvm = data; >> + } >> + >> + return NOTIFY_OK; >> +} >> + >> +static int vfio_ap_mdev_open(struct mdev_device *mdev) >> +{ >> + struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev); >> + unsigned long events; >> + int ret; >> + >> + matrix_mdev->group_notifier.notifier_call = >> vfio_ap_mdev_group_notifier; >> + events = VFIO_GROUP_NOTIFY_SET_KVM; >> + >> + ret = vfio_register_notifier(mdev_dev(mdev), VFIO_GROUP_NOTIFY, >> + &events, &matrix_mdev->group_notifier); >> + if (ret) >> + return ret; >> + >> + ret = kvm_ap_interpret_instructions(matrix_mdev->kvm, true); > > Do you need this call ? > apie is always enabled in KVM if AP instructions are available.
I suppose we don't, in which case we don't need the kvm_ap_interpret_instructions() function either ... at least not until we implement interception.
> > > Setting or not the interpretation is done for the VM in a all. > It is not the right place to do it here since open is device dependent.
As I stated above, at this time we probably do not need this, however; that will not always be the case. The setting is and always will be for the VM in all - unless the architecture changes - because it is controlled by a single bit (ECA.28). If you recall, I originally set interpretation in the vfio_ap device driver when notified of the VFIO_GROUP_NOTIFY_SET_KVM event. I believe ultimately that it is the device driver that should set the value for apie.
> > > Or we only have one device in the VM at a time. > In this case, shouldn't we make it official by returning -EEXIST for > the second call?
We do allow only one vfio-ap device at a time. QEMU will allow only one vfio-ap device to be configured for a guest. Should we also put a check in here?
> > > >> + if (ret) >> + return ret; >> + >> + ret = kvm_ap_configure_matrix(matrix_mdev->kvm, >> + matrix_mdev->matrix); >> + >> + return ret; >> +} >> + >> +static void vfio_ap_mdev_release(struct mdev_device *mdev) >> +{ >> + struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev); >> + >> + kvm_ap_deconfigure_matrix(matrix_mdev->kvm); >> + kvm_ap_interpret_instructions(matrix_mdev->kvm, false); > > This call clears the apie in KVM. > This is only OK if we have a single device present until the end of > the VM, > otherwise AP instructions in the guest will fail after the release > until the end of the VM > or until a new device is plugged.
See Message ID: <1523819244-29954-5-git-send-email-akrowiak@linux.vnet.ibm.com> on the qemu mailing list. There will be only one vfio-ap device allowed for the MVP model.
> > > >> + vfio_unregister_notifier(mdev_dev(mdev), VFIO_GROUP_NOTIFY, >> + &matrix_mdev->group_notifier); >> +} >> + >> static ssize_t name_show(struct kobject *kobj, struct device *dev, >> char *buf) >> { >> return sprintf(buf, "%s\n", VFIO_AP_MDEV_NAME_HWVIRT); >> @@ -754,6 +802,8 @@ static ssize_t matrix_show(struct device *dev, >> struct device_attribute *attr, >> .mdev_attr_groups = vfio_ap_mdev_attr_groups, >> .create = vfio_ap_mdev_create, >> .remove = vfio_ap_mdev_remove, >> + .open = vfio_ap_mdev_open, >> + .release = vfio_ap_mdev_release, >> }; >> >> int vfio_ap_mdev_register(struct ap_matrix *ap_matrix) >> diff --git a/drivers/s390/crypto/vfio_ap_private.h >> b/drivers/s390/crypto/vfio_ap_private.h >> index f248faf..48e2806 100644 >> --- a/drivers/s390/crypto/vfio_ap_private.h >> +++ b/drivers/s390/crypto/vfio_ap_private.h >> @@ -31,6 +31,8 @@ struct ap_matrix { >> >> struct ap_matrix_mdev { >> struct kvm_ap_matrix *matrix; >> + struct notifier_block group_notifier; >> + struct kvm *kvm; >> }; >> >> static inline struct ap_matrix *to_ap_matrix(struct device *dev) > >
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