| Message ID | 20201223011606.5265-7-akrowiak@linux.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | s390/vfio-ap: dynamic configuration support | expand |
On Tue, 22 Dec 2020 20:15:57 -0500 Tony Krowiak <akrowiak@linux.ibm.com> wrote: > The current implementation does not allow assignment of an AP adapter or > domain to an mdev device if each APQN resulting from the assignment > does not reference an AP queue device that is bound to the vfio_ap device > driver. This patch allows assignment of AP resources to the matrix mdev as > long as the APQNs resulting from the assignment: > 1. Are not reserved by the AP BUS for use by the zcrypt device drivers. > 2. Are not assigned to another matrix mdev. > > The rationale behind this is twofold: > 1. The AP architecture does not preclude assignment of APQNs to an AP > configuration that are not available to the system. > 2. APQNs that do not reference a queue device bound to the vfio_ap > device driver will not be assigned to the guest's CRYCB, so the > guest will not get access to queues not bound to the vfio_ap driver. You didn't tell us about the changed error code. Also notice that this point we don't have neither filtering nor in-use. This used to be patch 11, and most of that stuff used to be in place. But I'm going to trust you, if you say its fine to enable it this early. > > Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com> > --- > drivers/s390/crypto/vfio_ap_ops.c | 241 ++++++++---------------------- > 1 file changed, 62 insertions(+), 179 deletions(-) > > diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c > index cdcc6378b4a5..2d58b39977be 100644 > --- a/drivers/s390/crypto/vfio_ap_ops.c > +++ b/drivers/s390/crypto/vfio_ap_ops.c > @@ -379,134 +379,37 @@ static struct attribute_group *vfio_ap_mdev_type_groups[] = { > NULL, > }; > > -struct vfio_ap_queue_reserved { > - unsigned long *apid; > - unsigned long *apqi; > - bool reserved; > -}; > +#define MDEV_SHARING_ERR "Userspace may not re-assign queue %02lx.%04lx " \ > + "already assigned to %s" > > -/** > - * vfio_ap_has_queue > - * > - * @dev: an AP queue device > - * @data: a struct vfio_ap_queue_reserved reference > - * > - * Flags whether the AP queue device (@dev) has a queue ID containing the APQN, > - * apid or apqi specified in @data: > - * > - * - If @data contains both an apid and apqi value, then @data will be flagged > - * as reserved if the APID and APQI fields for the AP queue device matches > - * > - * - If @data contains only an apid value, @data will be flagged as > - * reserved if the APID field in the AP queue device matches > - * > - * - If @data contains only an apqi value, @data will be flagged as > - * reserved if the APQI field in the AP queue device matches > - * > - * Returns 0 to indicate the input to function succeeded. Returns -EINVAL if > - * @data does not contain either an apid or apqi. > - */ > -static int vfio_ap_has_queue(struct device *dev, void *data) > +static void vfio_ap_mdev_log_sharing_err(const char *mdev_name, > + unsigned long *apm, > + unsigned long *aqm) [..] > - return 0; > + for_each_set_bit_inv(apid, apm, AP_DEVICES) > + for_each_set_bit_inv(apqi, aqm, AP_DOMAINS) > + pr_warn(MDEV_SHARING_ERR, apid, apqi, mdev_name); I would prefer dev_warn() here. We know which device is about to get more queues, and this device can provide a clue regarding the initiator. Also I believe a warning is too heavy handed here. Warnings should not be ignored. This is a condition that can emerge during normal operation, AFAIU. Or am I worng? > } > > /** > * vfio_ap_mdev_verify_no_sharing > * > - * Verifies that the APQNs derived from the cross product of the AP adapter IDs > - * and AP queue indexes comprising the AP matrix are not configured for another > - * mediated device. AP queue sharing is not allowed. > + * Verifies that each APQN derived from the Cartesian product of the AP adapter > + * IDs and AP queue indexes comprising the AP matrix are not configured for > + * another mediated device. AP queue sharing is not allowed. > * > - * @matrix_mdev: the mediated matrix device > + * @matrix_mdev: the mediated matrix device to which the APQNs being verified > + * are assigned. > + * @mdev_apm: mask indicating the APIDs of the APQNs to be verified > + * @mdev_aqm: mask indicating the APQIs of the APQNs to be verified > * > - * Returns 0 if the APQNs are not shared, otherwise; returns -EADDRINUSE. > + * Returns 0 if the APQNs are not shared, otherwise; returns -EBUSY. > */ > -static int vfio_ap_mdev_verify_no_sharing(struct ap_matrix_mdev *matrix_mdev) > +static int vfio_ap_mdev_verify_no_sharing(struct ap_matrix_mdev *matrix_mdev, > + unsigned long *mdev_apm, > + unsigned long *mdev_aqm) > { > struct ap_matrix_mdev *lstdev; > DECLARE_BITMAP(apm, AP_DEVICES); > @@ -523,20 +426,31 @@ static int vfio_ap_mdev_verify_no_sharing(struct ap_matrix_mdev *matrix_mdev) > * We work on full longs, as we can only exclude the leftover > * bits in non-inverse order. The leftover is all zeros. > */ > - if (!bitmap_and(apm, matrix_mdev->matrix.apm, > - lstdev->matrix.apm, AP_DEVICES)) > + if (!bitmap_and(apm, mdev_apm, lstdev->matrix.apm, AP_DEVICES)) > continue; > > - if (!bitmap_and(aqm, matrix_mdev->matrix.aqm, > - lstdev->matrix.aqm, AP_DOMAINS)) > + if (!bitmap_and(aqm, mdev_aqm, lstdev->matrix.aqm, AP_DOMAINS)) > continue; > > - return -EADDRINUSE; > + vfio_ap_mdev_log_sharing_err(dev_name(mdev_dev(lstdev->mdev)), > + apm, aqm); > + > + return -EBUSY; Why do we change -EADDRINUSE to -EBUSY? This gets bubbled up to userspace, or? So a tool that checks for the other mdev has it condition by checking for -EADDRINUSE, would be confused... > } > > return 0; > } > > +static int vfio_ap_mdev_validate_masks(struct ap_matrix_mdev *matrix_mdev, > + unsigned long *mdev_apm, > + unsigned long *mdev_aqm) > +{ > + if (ap_apqn_in_matrix_owned_by_def_drv(mdev_apm, mdev_aqm)) > + return -EADDRNOTAVAIL; > + > + return vfio_ap_mdev_verify_no_sharing(matrix_mdev, mdev_apm, mdev_aqm); > +} > + > static void vfio_ap_mdev_link_queue(struct ap_matrix_mdev *matrix_mdev, > struct vfio_ap_queue *q) > { > @@ -608,10 +522,10 @@ static void vfio_ap_mdev_link_adapter(struct ap_matrix_mdev *matrix_mdev, > * driver; or, if no APQIs have yet been assigned, the APID is not > * contained in an APQN bound to the vfio_ap device driver. > * > - * 4. -EADDRINUSE > + * 4. -EBUSY > * An APQN derived from the cross product of the APID being assigned > * and the APQIs previously assigned is being used by another mediated > - * matrix device > + * matrix device or the mdev lock could not be acquired. This is premature. We don't use try_lock yet. [..] > static void vfio_ap_mdev_link_domain(struct ap_matrix_mdev *matrix_mdev, > unsigned long apqi) > { > @@ -774,10 +660,10 @@ static void vfio_ap_mdev_link_domain(struct ap_matrix_mdev *matrix_mdev, > * driver; or, if no APIDs have yet been assigned, the APQI is not > * contained in an APQN bound to the vfio_ap device driver. > * > - * 4. -EADDRINUSE > + * 4. -BUSY > * An APQN derived from the cross product of the APQI being assigned > * and the APIDs previously assigned is being used by another mediated > - * matrix device > + * matrix device or the mdev lock could not be acquired. Same here as above. Otherwise looks good. [..]
On 1/11/21 3:40 PM, Halil Pasic wrote: > On Tue, 22 Dec 2020 20:15:57 -0500 > Tony Krowiak <akrowiak@linux.ibm.com> wrote: > >> The current implementation does not allow assignment of an AP adapter or >> domain to an mdev device if each APQN resulting from the assignment >> does not reference an AP queue device that is bound to the vfio_ap device >> driver. This patch allows assignment of AP resources to the matrix mdev as >> long as the APQNs resulting from the assignment: >> 1. Are not reserved by the AP BUS for use by the zcrypt device drivers. >> 2. Are not assigned to another matrix mdev. >> >> The rationale behind this is twofold: >> 1. The AP architecture does not preclude assignment of APQNs to an AP >> configuration that are not available to the system. >> 2. APQNs that do not reference a queue device bound to the vfio_ap >> device driver will not be assigned to the guest's CRYCB, so the >> guest will not get access to queues not bound to the vfio_ap driver. > You didn't tell us about the changed error code. I am assuming you are talking about returning -EBUSY from the vfio_ap_mdev_verify_no_sharing() function instead of -EADDRINUSE. I'm going to change this back per your comments below. > > Also notice that this point we don't have neither filtering nor in-use. > This used to be patch 11, and most of that stuff used to be in place. But > I'm going to trust you, if you say its fine to enable it this early. The patch order was changed due to your review comments in in Message ID <20201126165431.6ef1457a.pasic@linux.ibm.com>, patch 07/17 in the v12 series. In order to ensure that only queues bound to the vfio_ap driver are given to the guest, I'm going to create a patch that will preceded this one which introduces the filtering code currently introduced in the patch 12/17, the hot plug patch. > >> Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com> >> --- >> drivers/s390/crypto/vfio_ap_ops.c | 241 ++++++++---------------------- >> 1 file changed, 62 insertions(+), 179 deletions(-) >> >> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c >> index cdcc6378b4a5..2d58b39977be 100644 >> --- a/drivers/s390/crypto/vfio_ap_ops.c >> +++ b/drivers/s390/crypto/vfio_ap_ops.c >> @@ -379,134 +379,37 @@ static struct attribute_group *vfio_ap_mdev_type_groups[] = { >> NULL, >> }; >> >> -struct vfio_ap_queue_reserved { >> - unsigned long *apid; >> - unsigned long *apqi; >> - bool reserved; >> -}; >> +#define MDEV_SHARING_ERR "Userspace may not re-assign queue %02lx.%04lx " \ >> + "already assigned to %s" >> >> -/** >> - * vfio_ap_has_queue >> - * >> - * @dev: an AP queue device >> - * @data: a struct vfio_ap_queue_reserved reference >> - * >> - * Flags whether the AP queue device (@dev) has a queue ID containing the APQN, >> - * apid or apqi specified in @data: >> - * >> - * - If @data contains both an apid and apqi value, then @data will be flagged >> - * as reserved if the APID and APQI fields for the AP queue device matches >> - * >> - * - If @data contains only an apid value, @data will be flagged as >> - * reserved if the APID field in the AP queue device matches >> - * >> - * - If @data contains only an apqi value, @data will be flagged as >> - * reserved if the APQI field in the AP queue device matches >> - * >> - * Returns 0 to indicate the input to function succeeded. Returns -EINVAL if >> - * @data does not contain either an apid or apqi. >> - */ >> -static int vfio_ap_has_queue(struct device *dev, void *data) >> +static void vfio_ap_mdev_log_sharing_err(const char *mdev_name, >> + unsigned long *apm, >> + unsigned long *aqm) > [..] >> - return 0; >> + for_each_set_bit_inv(apid, apm, AP_DEVICES) >> + for_each_set_bit_inv(apqi, aqm, AP_DOMAINS) >> + pr_warn(MDEV_SHARING_ERR, apid, apqi, mdev_name); > I would prefer dev_warn() here. We know which device is about to get > more queues, and this device can provide a clue regarding the initiator. Will do. > > Also I believe a warning is too heavy handed here. Warnings should not > be ignored. This is a condition that can emerge during normal operation, > AFAIU. Or am I worng? It can happen during normal operation, but we had this discussion in the previous review. Both Connie and I felt it should be a warning since this message is the only way for a user to identify the queues in use. A message of lower severity may not get logged depriving the user from easily determining why an adapter or domain could not be assigned. > >> } >> >> /** >> * vfio_ap_mdev_verify_no_sharing >> * >> - * Verifies that the APQNs derived from the cross product of the AP adapter IDs >> - * and AP queue indexes comprising the AP matrix are not configured for another >> - * mediated device. AP queue sharing is not allowed. >> + * Verifies that each APQN derived from the Cartesian product of the AP adapter >> + * IDs and AP queue indexes comprising the AP matrix are not configured for >> + * another mediated device. AP queue sharing is not allowed. >> * >> - * @matrix_mdev: the mediated matrix device >> + * @matrix_mdev: the mediated matrix device to which the APQNs being verified >> + * are assigned. >> + * @mdev_apm: mask indicating the APIDs of the APQNs to be verified >> + * @mdev_aqm: mask indicating the APQIs of the APQNs to be verified >> * >> - * Returns 0 if the APQNs are not shared, otherwise; returns -EADDRINUSE. >> + * Returns 0 if the APQNs are not shared, otherwise; returns -EBUSY. >> */ >> -static int vfio_ap_mdev_verify_no_sharing(struct ap_matrix_mdev *matrix_mdev) >> +static int vfio_ap_mdev_verify_no_sharing(struct ap_matrix_mdev *matrix_mdev, >> + unsigned long *mdev_apm, >> + unsigned long *mdev_aqm) >> { >> struct ap_matrix_mdev *lstdev; >> DECLARE_BITMAP(apm, AP_DEVICES); >> @@ -523,20 +426,31 @@ static int vfio_ap_mdev_verify_no_sharing(struct ap_matrix_mdev *matrix_mdev) >> * We work on full longs, as we can only exclude the leftover >> * bits in non-inverse order. The leftover is all zeros. >> */ >> - if (!bitmap_and(apm, matrix_mdev->matrix.apm, >> - lstdev->matrix.apm, AP_DEVICES)) >> + if (!bitmap_and(apm, mdev_apm, lstdev->matrix.apm, AP_DEVICES)) >> continue; >> >> - if (!bitmap_and(aqm, matrix_mdev->matrix.aqm, >> - lstdev->matrix.aqm, AP_DOMAINS)) >> + if (!bitmap_and(aqm, mdev_aqm, lstdev->matrix.aqm, AP_DOMAINS)) >> continue; >> >> - return -EADDRINUSE; >> + vfio_ap_mdev_log_sharing_err(dev_name(mdev_dev(lstdev->mdev)), >> + apm, aqm); >> + >> + return -EBUSY; > Why do we change -EADDRINUSE to -EBUSY? This gets bubbled up to > userspace, or? So a tool that checks for the other mdev has it > condition by checking for -EADDRINUSE, would be confused... Back in v8 of the series, Christian suggested the occurrences of -EADDRINUSE should be replaced by the more appropriate -EBUSY (Message ID <d7954c15-b14f-d6e5-0193-aadca61883a8@de.ibm.com>), so I changed it here. It does get bubbled up to userspace, so you make a valid point. I will change it back. I will, however, set the value returned from the __verify_card_reservations() function in ap_bus.c to -EBUSY as suggested by Christian. > >> } >> >> return 0; >> } >> >> +static int vfio_ap_mdev_validate_masks(struct ap_matrix_mdev *matrix_mdev, >> + unsigned long *mdev_apm, >> + unsigned long *mdev_aqm) >> +{ >> + if (ap_apqn_in_matrix_owned_by_def_drv(mdev_apm, mdev_aqm)) >> + return -EADDRNOTAVAIL; >> + >> + return vfio_ap_mdev_verify_no_sharing(matrix_mdev, mdev_apm, mdev_aqm); >> +} >> + >> static void vfio_ap_mdev_link_queue(struct ap_matrix_mdev *matrix_mdev, >> struct vfio_ap_queue *q) >> { >> @@ -608,10 +522,10 @@ static void vfio_ap_mdev_link_adapter(struct ap_matrix_mdev *matrix_mdev, >> * driver; or, if no APQIs have yet been assigned, the APID is not >> * contained in an APQN bound to the vfio_ap device driver. >> * >> - * 4. -EADDRINUSE >> + * 4. -EBUSY >> * An APQN derived from the cross product of the APID being assigned >> * and the APQIs previously assigned is being used by another mediated >> - * matrix device >> + * matrix device or the mdev lock could not be acquired. > This is premature. We don't use try_lock yet. Yes it is, the comment describing the -EBUSY return code will be moved to patch 11/15 where it is the try_lock is introduced. > > [..] > >> static void vfio_ap_mdev_link_domain(struct ap_matrix_mdev *matrix_mdev, >> unsigned long apqi) >> { >> @@ -774,10 +660,10 @@ static void vfio_ap_mdev_link_domain(struct ap_matrix_mdev *matrix_mdev, >> * driver; or, if no APIDs have yet been assigned, the APQI is not >> * contained in an APQN bound to the vfio_ap device driver. >> * >> - * 4. -EADDRINUSE >> + * 4. -BUSY >> * An APQN derived from the cross product of the APQI being assigned >> * and the APIDs previously assigned is being used by another mediated >> - * matrix device >> + * matrix device or the mdev lock could not be acquired. > Same here as above. > > Otherwise looks good. > > [..]
On Thu, 14 Jan 2021 12:54:39 -0500 Tony Krowiak <akrowiak@linux.ibm.com> wrote: > On 1/11/21 3:40 PM, Halil Pasic wrote: > > On Tue, 22 Dec 2020 20:15:57 -0500 > > Tony Krowiak <akrowiak@linux.ibm.com> wrote: > > > >> The current implementation does not allow assignment of an AP adapter or > >> domain to an mdev device if each APQN resulting from the assignment > >> does not reference an AP queue device that is bound to the vfio_ap device > >> driver. This patch allows assignment of AP resources to the matrix mdev as > >> long as the APQNs resulting from the assignment: > >> 1. Are not reserved by the AP BUS for use by the zcrypt device drivers. > >> 2. Are not assigned to another matrix mdev. > >> > >> The rationale behind this is twofold: > >> 1. The AP architecture does not preclude assignment of APQNs to an AP > >> configuration that are not available to the system. > >> 2. APQNs that do not reference a queue device bound to the vfio_ap > >> device driver will not be assigned to the guest's CRYCB, so the > >> guest will not get access to queues not bound to the vfio_ap driver. > > You didn't tell us about the changed error code. > > I am assuming you are talking about returning -EBUSY from > the vfio_ap_mdev_verify_no_sharing() function instead of > -EADDRINUSE. I'm going to change this back per your comments > below. > > > > > Also notice that this point we don't have neither filtering nor in-use. > > This used to be patch 11, and most of that stuff used to be in place. But > > I'm going to trust you, if you say its fine to enable it this early. > > The patch order was changed due to your review comments in > in Message ID <20201126165431.6ef1457a.pasic@linux.ibm.com>, > patch 07/17 in the v12 series. In order to ensure that only queues > bound to the vfio_ap driver are given to the guest, I'm going to > create a patch that will preceded this one which introduces the > filtering code currently introduced in the patch 12/17, the hot > plug patch. > I don't want to delay this any further, so it's up to you. I don't think we will get the in-between steps perfect anyway. I've re-readthe Message ID <20201126165431.6ef1457a.pasic@linux.ibm.com> and I didn't ask for this change. I pointed out a problem, and said, maybe it can be solved by reordering, I didn't think it through. [..]
On Thu, 14 Jan 2021 12:54:39 -0500 Tony Krowiak <akrowiak@linux.ibm.com> wrote: > >> /** > >> * vfio_ap_mdev_verify_no_sharing > >> * > >> - * Verifies that the APQNs derived from the cross product of the AP adapter IDs > >> - * and AP queue indexes comprising the AP matrix are not configured for another > >> - * mediated device. AP queue sharing is not allowed. > >> + * Verifies that each APQN derived from the Cartesian product of the AP adapter > >> + * IDs and AP queue indexes comprising the AP matrix are not configured for > >> + * another mediated device. AP queue sharing is not allowed. > >> * > >> - * @matrix_mdev: the mediated matrix device > >> + * @matrix_mdev: the mediated matrix device to which the APQNs being verified > >> + * are assigned. > >> + * @mdev_apm: mask indicating the APIDs of the APQNs to be verified > >> + * @mdev_aqm: mask indicating the APQIs of the APQNs to be verified > >> * > >> - * Returns 0 if the APQNs are not shared, otherwise; returns -EADDRINUSE. > >> + * Returns 0 if the APQNs are not shared, otherwise; returns -EBUSY. > >> */ > >> -static int vfio_ap_mdev_verify_no_sharing(struct ap_matrix_mdev *matrix_mdev) > >> +static int vfio_ap_mdev_verify_no_sharing(struct ap_matrix_mdev *matrix_mdev, > >> + unsigned long *mdev_apm, > >> + unsigned long *mdev_aqm) > >> { > >> struct ap_matrix_mdev *lstdev; > >> DECLARE_BITMAP(apm, AP_DEVICES); > >> @@ -523,20 +426,31 @@ static int vfio_ap_mdev_verify_no_sharing(struct ap_matrix_mdev *matrix_mdev) > >> * We work on full longs, as we can only exclude the leftover > >> * bits in non-inverse order. The leftover is all zeros. > >> */ > >> - if (!bitmap_and(apm, matrix_mdev->matrix.apm, > >> - lstdev->matrix.apm, AP_DEVICES)) > >> + if (!bitmap_and(apm, mdev_apm, lstdev->matrix.apm, AP_DEVICES)) > >> continue; > >> > >> - if (!bitmap_and(aqm, matrix_mdev->matrix.aqm, > >> - lstdev->matrix.aqm, AP_DOMAINS)) > >> + if (!bitmap_and(aqm, mdev_aqm, lstdev->matrix.aqm, AP_DOMAINS)) > >> continue; > >> > >> - return -EADDRINUSE; > >> + vfio_ap_mdev_log_sharing_err(dev_name(mdev_dev(lstdev->mdev)), > >> + apm, aqm); > >> + > >> + return -EBUSY; > > Why do we change -EADDRINUSE to -EBUSY? This gets bubbled up to > > userspace, or? So a tool that checks for the other mdev has it > > condition by checking for -EADDRINUSE, would be confused... > > Back in v8 of the series, Christian suggested the occurrences > of -EADDRINUSE should be replaced by the more appropriate > -EBUSY (Message ID <d7954c15-b14f-d6e5-0193-aadca61883a8@de.ibm.com>), > so I changed it here. It does get bubbled up to userspace, so you make a > valid point. I will > change it back. I will, however, set the value returned from the > __verify_card_reservations() function in ap_bus.c to -EBUSY as > suggested by Christian. As long as the error code for an ephemeral failure due to can't take a lock right now, and the error code for a failure due to a sharing conflict are (which most likely requires admin action to be resolved) I'm fine. Choosing EBUSY for sharing conflict, and something else for can't take lock for the bus attributes, while choosing EADDRINUSE for sharing conflict, and EBUSY for can't take lock in the case of the mdev attributes (assign_*; unassign_*) sounds confusing to me, but is still better than collating the two conditions. Maybe we can choose EAGAIN or EWOULDBLOCK for the can't take the lock right now. I don't know. I'm open to suggestions. And if Christian wants to change this for the already released interfaces, I will have to live with that. But it has to be a conscious decision at least. What I consider tricky about EBUSY, is that according to my intuition, in pseudocode, object.operation(argument) returns -EBUSY probably tells me that object is busy (i.e. is in the middle of something incompatible with performing operation). In our case, it is not the object that is busy, but the resource denoted by the argument. Regards, Halil
On 1/14/21 8:44 PM, Halil Pasic wrote: > On Thu, 14 Jan 2021 12:54:39 -0500 > Tony Krowiak <akrowiak@linux.ibm.com> wrote: > >>>> /** >>>> * vfio_ap_mdev_verify_no_sharing >>>> * >>>> - * Verifies that the APQNs derived from the cross product of the AP adapter IDs >>>> - * and AP queue indexes comprising the AP matrix are not configured for another >>>> - * mediated device. AP queue sharing is not allowed. >>>> + * Verifies that each APQN derived from the Cartesian product of the AP adapter >>>> + * IDs and AP queue indexes comprising the AP matrix are not configured for >>>> + * another mediated device. AP queue sharing is not allowed. >>>> * >>>> - * @matrix_mdev: the mediated matrix device >>>> + * @matrix_mdev: the mediated matrix device to which the APQNs being verified >>>> + * are assigned. >>>> + * @mdev_apm: mask indicating the APIDs of the APQNs to be verified >>>> + * @mdev_aqm: mask indicating the APQIs of the APQNs to be verified >>>> * >>>> - * Returns 0 if the APQNs are not shared, otherwise; returns -EADDRINUSE. >>>> + * Returns 0 if the APQNs are not shared, otherwise; returns -EBUSY. >>>> */ >>>> -static int vfio_ap_mdev_verify_no_sharing(struct ap_matrix_mdev *matrix_mdev) >>>> +static int vfio_ap_mdev_verify_no_sharing(struct ap_matrix_mdev *matrix_mdev, >>>> + unsigned long *mdev_apm, >>>> + unsigned long *mdev_aqm) >>>> { >>>> struct ap_matrix_mdev *lstdev; >>>> DECLARE_BITMAP(apm, AP_DEVICES); >>>> @@ -523,20 +426,31 @@ static int vfio_ap_mdev_verify_no_sharing(struct ap_matrix_mdev *matrix_mdev) >>>> * We work on full longs, as we can only exclude the leftover >>>> * bits in non-inverse order. The leftover is all zeros. >>>> */ >>>> - if (!bitmap_and(apm, matrix_mdev->matrix.apm, >>>> - lstdev->matrix.apm, AP_DEVICES)) >>>> + if (!bitmap_and(apm, mdev_apm, lstdev->matrix.apm, AP_DEVICES)) >>>> continue; >>>> >>>> - if (!bitmap_and(aqm, matrix_mdev->matrix.aqm, >>>> - lstdev->matrix.aqm, AP_DOMAINS)) >>>> + if (!bitmap_and(aqm, mdev_aqm, lstdev->matrix.aqm, AP_DOMAINS)) >>>> continue; >>>> >>>> - return -EADDRINUSE; >>>> + vfio_ap_mdev_log_sharing_err(dev_name(mdev_dev(lstdev->mdev)), >>>> + apm, aqm); >>>> + >>>> + return -EBUSY; >>> Why do we change -EADDRINUSE to -EBUSY? This gets bubbled up to >>> userspace, or? So a tool that checks for the other mdev has it >>> condition by checking for -EADDRINUSE, would be confused... >> Back in v8 of the series, Christian suggested the occurrences >> of -EADDRINUSE should be replaced by the more appropriate >> -EBUSY (Message ID <d7954c15-b14f-d6e5-0193-aadca61883a8@de.ibm.com>), >> so I changed it here. It does get bubbled up to userspace, so you make a >> valid point. I will >> change it back. I will, however, set the value returned from the >> __verify_card_reservations() function in ap_bus.c to -EBUSY as >> suggested by Christian. > As long as the error code for an ephemeral failure due to can't take a > lock right now, and the error code for a failure due to a sharing > conflict are (which most likely requires admin action to be resolved) > I'm fine. > > Choosing EBUSY for sharing conflict, and something else for can't take > lock for the bus attributes, while choosing EADDRINUSE for sharing > conflict, and EBUSY for can't take lock in the case of the mdev > attributes (assign_*; unassign_*) sounds confusing to me, but is still > better than collating the two conditions. Maybe we can choose EAGAIN > or EWOULDBLOCK for the can't take the lock right now. I don't know. I was in the process of creating the change log for v14 of this patch series and realized I never addressed this. I think EAGAIN would be a better return code for the mutex_trylock failures in the mdev assign/unassign operations. > > I'm open to suggestions. And if Christian wants to change this for > the already released interfaces, I will have to live with that. But it > has to be a conscious decision at least. > > What I consider tricky about EBUSY, is that according to my intuition, > in pseudocode, object.operation(argument) returns -EBUSY probably tells > me that object is busy (i.e. is in the middle of something incompatible > with performing operation). In our case, it is not the object that is > busy, but the resource denoted by the argument. > > Regards, > Halil
diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c index cdcc6378b4a5..2d58b39977be 100644 --- a/drivers/s390/crypto/vfio_ap_ops.c +++ b/drivers/s390/crypto/vfio_ap_ops.c @@ -379,134 +379,37 @@ static struct attribute_group *vfio_ap_mdev_type_groups[] = { NULL, }; -struct vfio_ap_queue_reserved { - unsigned long *apid; - unsigned long *apqi; - bool reserved; -}; +#define MDEV_SHARING_ERR "Userspace may not re-assign queue %02lx.%04lx " \ + "already assigned to %s" -/** - * vfio_ap_has_queue - * - * @dev: an AP queue device - * @data: a struct vfio_ap_queue_reserved reference - * - * Flags whether the AP queue device (@dev) has a queue ID containing the APQN, - * apid or apqi specified in @data: - * - * - If @data contains both an apid and apqi value, then @data will be flagged - * as reserved if the APID and APQI fields for the AP queue device matches - * - * - If @data contains only an apid value, @data will be flagged as - * reserved if the APID field in the AP queue device matches - * - * - If @data contains only an apqi value, @data will be flagged as - * reserved if the APQI field in the AP queue device matches - * - * Returns 0 to indicate the input to function succeeded. Returns -EINVAL if - * @data does not contain either an apid or apqi. - */ -static int vfio_ap_has_queue(struct device *dev, void *data) +static void vfio_ap_mdev_log_sharing_err(const char *mdev_name, + unsigned long *apm, + unsigned long *aqm) { - struct vfio_ap_queue_reserved *qres = data; - struct ap_queue *ap_queue = to_ap_queue(dev); - ap_qid_t qid; - unsigned long id; - - if (qres->apid && qres->apqi) { - qid = AP_MKQID(*qres->apid, *qres->apqi); - if (qid == ap_queue->qid) - qres->reserved = true; - } else if (qres->apid && !qres->apqi) { - id = AP_QID_CARD(ap_queue->qid); - if (id == *qres->apid) - qres->reserved = true; - } else if (!qres->apid && qres->apqi) { - id = AP_QID_QUEUE(ap_queue->qid); - if (id == *qres->apqi) - qres->reserved = true; - } else { - return -EINVAL; - } + unsigned long apid, apqi; - return 0; -} - -/** - * vfio_ap_verify_queue_reserved - * - * @matrix_dev: a mediated matrix device - * @apid: an AP adapter ID - * @apqi: an AP queue index - * - * Verifies that the AP queue with @apid/@apqi is reserved by the VFIO AP device - * driver according to the following rules: - * - * - If both @apid and @apqi are not NULL, then there must be an AP queue - * device bound to the vfio_ap driver with the APQN identified by @apid and - * @apqi - * - * - If only @apid is not NULL, then there must be an AP queue device bound - * to the vfio_ap driver with an APQN containing @apid - * - * - If only @apqi is not NULL, then there must be an AP queue device bound - * to the vfio_ap driver with an APQN containing @apqi - * - * Returns 0 if the AP queue is reserved; otherwise, returns -EADDRNOTAVAIL. - */ -static int vfio_ap_verify_queue_reserved(unsigned long *apid, - unsigned long *apqi) -{ - int ret; - struct vfio_ap_queue_reserved qres; - - qres.apid = apid; - qres.apqi = apqi; - qres.reserved = false; - - ret = driver_for_each_device(&matrix_dev->vfio_ap_drv->driver, NULL, - &qres, vfio_ap_has_queue); - if (ret) - return ret; - - if (qres.reserved) - return 0; - - return -EADDRNOTAVAIL; -} - -static int -vfio_ap_mdev_verify_queues_reserved_for_apid(struct ap_matrix_mdev *matrix_mdev, - unsigned long apid) -{ - int ret; - unsigned long apqi; - unsigned long nbits = matrix_mdev->matrix.aqm_max + 1; - - if (find_first_bit_inv(matrix_mdev->matrix.aqm, nbits) >= nbits) - return vfio_ap_verify_queue_reserved(&apid, NULL); - - for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm, nbits) { - ret = vfio_ap_verify_queue_reserved(&apid, &apqi); - if (ret) - return ret; - } - - return 0; + for_each_set_bit_inv(apid, apm, AP_DEVICES) + for_each_set_bit_inv(apqi, aqm, AP_DOMAINS) + pr_warn(MDEV_SHARING_ERR, apid, apqi, mdev_name); } /** * vfio_ap_mdev_verify_no_sharing * - * Verifies that the APQNs derived from the cross product of the AP adapter IDs - * and AP queue indexes comprising the AP matrix are not configured for another - * mediated device. AP queue sharing is not allowed. + * Verifies that each APQN derived from the Cartesian product of the AP adapter + * IDs and AP queue indexes comprising the AP matrix are not configured for + * another mediated device. AP queue sharing is not allowed. * - * @matrix_mdev: the mediated matrix device + * @matrix_mdev: the mediated matrix device to which the APQNs being verified + * are assigned. + * @mdev_apm: mask indicating the APIDs of the APQNs to be verified + * @mdev_aqm: mask indicating the APQIs of the APQNs to be verified * - * Returns 0 if the APQNs are not shared, otherwise; returns -EADDRINUSE. + * Returns 0 if the APQNs are not shared, otherwise; returns -EBUSY. */ -static int vfio_ap_mdev_verify_no_sharing(struct ap_matrix_mdev *matrix_mdev) +static int vfio_ap_mdev_verify_no_sharing(struct ap_matrix_mdev *matrix_mdev, + unsigned long *mdev_apm, + unsigned long *mdev_aqm) { struct ap_matrix_mdev *lstdev; DECLARE_BITMAP(apm, AP_DEVICES); @@ -523,20 +426,31 @@ static int vfio_ap_mdev_verify_no_sharing(struct ap_matrix_mdev *matrix_mdev) * We work on full longs, as we can only exclude the leftover * bits in non-inverse order. The leftover is all zeros. */ - if (!bitmap_and(apm, matrix_mdev->matrix.apm, - lstdev->matrix.apm, AP_DEVICES)) + if (!bitmap_and(apm, mdev_apm, lstdev->matrix.apm, AP_DEVICES)) continue; - if (!bitmap_and(aqm, matrix_mdev->matrix.aqm, - lstdev->matrix.aqm, AP_DOMAINS)) + if (!bitmap_and(aqm, mdev_aqm, lstdev->matrix.aqm, AP_DOMAINS)) continue; - return -EADDRINUSE; + vfio_ap_mdev_log_sharing_err(dev_name(mdev_dev(lstdev->mdev)), + apm, aqm); + + return -EBUSY; } return 0; } +static int vfio_ap_mdev_validate_masks(struct ap_matrix_mdev *matrix_mdev, + unsigned long *mdev_apm, + unsigned long *mdev_aqm) +{ + if (ap_apqn_in_matrix_owned_by_def_drv(mdev_apm, mdev_aqm)) + return -EADDRNOTAVAIL; + + return vfio_ap_mdev_verify_no_sharing(matrix_mdev, mdev_apm, mdev_aqm); +} + static void vfio_ap_mdev_link_queue(struct ap_matrix_mdev *matrix_mdev, struct vfio_ap_queue *q) { @@ -608,10 +522,10 @@ static void vfio_ap_mdev_link_adapter(struct ap_matrix_mdev *matrix_mdev, * driver; or, if no APQIs have yet been assigned, the APID is not * contained in an APQN bound to the vfio_ap device driver. * - * 4. -EADDRINUSE + * 4. -EBUSY * An APQN derived from the cross product of the APID being assigned * and the APQIs previously assigned is being used by another mediated - * matrix device + * matrix device or the mdev lock could not be acquired. */ static ssize_t assign_adapter_store(struct device *dev, struct device_attribute *attr, @@ -619,6 +533,7 @@ static ssize_t assign_adapter_store(struct device *dev, { int ret; unsigned long apid; + DECLARE_BITMAP(apm, AP_DEVICES); struct mdev_device *mdev = mdev_from_dev(dev); struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev); @@ -633,33 +548,24 @@ static ssize_t assign_adapter_store(struct device *dev, if (apid > matrix_mdev->matrix.apm_max) return -ENODEV; - /* - * Set the bit in the AP mask (APM) corresponding to the AP adapter - * number (APID). The bits in the mask, from most significant to least - * significant bit, correspond to APIDs 0-255. - */ + memset(apm, 0, sizeof(apm)); + set_bit_inv(apid, apm); + mutex_lock(&matrix_dev->lock); - ret = vfio_ap_mdev_verify_queues_reserved_for_apid(matrix_mdev, apid); - if (ret) - goto done; + ret = vfio_ap_mdev_validate_masks(matrix_mdev, apm, + matrix_mdev->matrix.aqm); + if (ret) { + mutex_unlock(&matrix_dev->lock); + return ret; + } set_bit_inv(apid, matrix_mdev->matrix.apm); - - ret = vfio_ap_mdev_verify_no_sharing(matrix_mdev); - if (ret) - goto share_err; - vfio_ap_mdev_link_adapter(matrix_mdev, apid); - ret = count; - goto done; -share_err: - clear_bit_inv(apid, matrix_mdev->matrix.apm); -done: mutex_unlock(&matrix_dev->lock); - return ret; + return count; } static DEVICE_ATTR_WO(assign_adapter); @@ -718,26 +624,6 @@ static ssize_t unassign_adapter_store(struct device *dev, } static DEVICE_ATTR_WO(unassign_adapter); -static int -vfio_ap_mdev_verify_queues_reserved_for_apqi(struct ap_matrix_mdev *matrix_mdev, - unsigned long apqi) -{ - int ret; - unsigned long apid; - unsigned long nbits = matrix_mdev->matrix.apm_max + 1; - - if (find_first_bit_inv(matrix_mdev->matrix.apm, nbits) >= nbits) - return vfio_ap_verify_queue_reserved(NULL, &apqi); - - for_each_set_bit_inv(apid, matrix_mdev->matrix.apm, nbits) { - ret = vfio_ap_verify_queue_reserved(&apid, &apqi); - if (ret) - return ret; - } - - return 0; -} - static void vfio_ap_mdev_link_domain(struct ap_matrix_mdev *matrix_mdev, unsigned long apqi) { @@ -774,10 +660,10 @@ static void vfio_ap_mdev_link_domain(struct ap_matrix_mdev *matrix_mdev, * driver; or, if no APIDs have yet been assigned, the APQI is not * contained in an APQN bound to the vfio_ap device driver. * - * 4. -EADDRINUSE + * 4. -BUSY * An APQN derived from the cross product of the APQI being assigned * and the APIDs previously assigned is being used by another mediated - * matrix device + * matrix device or the mdev lock could not be acquired. */ static ssize_t assign_domain_store(struct device *dev, struct device_attribute *attr, @@ -785,6 +671,7 @@ static ssize_t assign_domain_store(struct device *dev, { int ret; unsigned long apqi; + DECLARE_BITMAP(aqm, AP_DOMAINS); struct mdev_device *mdev = mdev_from_dev(dev); struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev); unsigned long max_apqi = matrix_mdev->matrix.aqm_max; @@ -799,28 +686,24 @@ static ssize_t assign_domain_store(struct device *dev, if (apqi > max_apqi) return -ENODEV; + memset(aqm, 0, sizeof(aqm)); + set_bit_inv(apqi, aqm); + mutex_lock(&matrix_dev->lock); - ret = vfio_ap_mdev_verify_queues_reserved_for_apqi(matrix_mdev, apqi); - if (ret) - goto done; + ret = vfio_ap_mdev_validate_masks(matrix_mdev, matrix_mdev->matrix.apm, + aqm); + if (ret) { + mutex_unlock(&matrix_dev->lock); + return ret; + } set_bit_inv(apqi, matrix_mdev->matrix.aqm); - - ret = vfio_ap_mdev_verify_no_sharing(matrix_mdev); - if (ret) - goto share_err; - vfio_ap_mdev_link_domain(matrix_mdev, apqi); - ret = count; - goto done; -share_err: - clear_bit_inv(apqi, matrix_mdev->matrix.aqm); -done: mutex_unlock(&matrix_dev->lock); - return ret; + return count; } static DEVICE_ATTR_WO(assign_domain);
The current implementation does not allow assignment of an AP adapter or domain to an mdev device if each APQN resulting from the assignment does not reference an AP queue device that is bound to the vfio_ap device driver. This patch allows assignment of AP resources to the matrix mdev as long as the APQNs resulting from the assignment: 1. Are not reserved by the AP BUS for use by the zcrypt device drivers. 2. Are not assigned to another matrix mdev. The rationale behind this is twofold: 1. The AP architecture does not preclude assignment of APQNs to an AP configuration that are not available to the system. 2. APQNs that do not reference a queue device bound to the vfio_ap device driver will not be assigned to the guest's CRYCB, so the guest will not get access to queues not bound to the vfio_ap driver. Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com> --- drivers/s390/crypto/vfio_ap_ops.c | 241 ++++++++---------------------- 1 file changed, 62 insertions(+), 179 deletions(-)