From mboxrd@z Thu Jan 1 00:00:00 1970 From: Cornelia Huck Subject: Re: [PATCH v9 17/22] s390: vfio-ap: zeroize the AP queues. Date: Fri, 17 Aug 2018 11:34:52 +0200 Message-ID: <20180817113452.5cee98e2.cohuck@redhat.com> References: <1534196899-16987-1-git-send-email-akrowiak@linux.vnet.ibm.com> <1534196899-16987-18-git-send-email-akrowiak@linux.vnet.ibm.com> <20180815182401.4cfa0a78.cohuck@redhat.com> <59fddbc0-49f5-c83b-144f-7390b80dfc9f@linux.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <59fddbc0-49f5-c83b-144f-7390b80dfc9f@linux.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-Archive: List-Post: To: Tony Krowiak Cc: Tony Krowiak , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, freude@de.ibm.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, borntraeger@de.ibm.com, kwankhede@nvidia.com, bjsdjshi@linux.vnet.ibm.com, pbonzini@redhat.com, alex.williamson@redhat.com, pmorel@linux.vnet.ibm.com, alifm@linux.vnet.ibm.com, mjrosato@linux.vnet.ibm.com, jjherne@linux.vnet.ibm.com, thuth@redhat.com, pasic@linux.vnet.ibm.com, berrange@redhat.com, fiuczy@linux.vnet.ibm.com, buendgen@de.ibm.com, frankja@linux.ibm.com List-ID: On Wed, 15 Aug 2018 16:36:32 -0400 Tony Krowiak wrote: > On 08/15/2018 12:24 PM, Cornelia Huck wrote: > > On Mon, 13 Aug 2018 17:48:14 -0400 > > Tony Krowiak wrote: > > > > Nit: please drop the leading period in the subject. > > I assume you mean the ending period? Err, of course. > > > > >> From: Tony Krowiak > >> > >> Let's call PAPQ(ZAPQ) to zeroize a queue: > >> > >> * For each queue configured for a mediated matrix device > >> when it is released. > >> > >> Zeroizing a queue resets the queue, clears all pending > >> messages for the queue entries and disables adapter interruptions > >> associated with the queue. > >> > >> Signed-off-by: Tony Krowiak > >> Reviewed-by: Halil Pasic > >> Tested-by: Michael Mueller > >> Tested-by: Farhan Ali > >> Signed-off-by: Christian Borntraeger > >> --- > >> drivers/s390/crypto/vfio_ap_ops.c | 25 +++++++++++++++++++++++++ > >> drivers/s390/crypto/vfio_ap_private.h | 25 +++++++++++++++++++++++++ > >> 2 files changed, 50 insertions(+), 0 deletions(-) > >> > >> diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h > >> index 3e8534b..34f982a 100644 > >> --- a/drivers/s390/crypto/vfio_ap_private.h > >> +++ b/drivers/s390/crypto/vfio_ap_private.h > >> @@ -74,4 +74,29 @@ struct ap_matrix_mdev { > >> extern int vfio_ap_mdev_register(void); > >> extern void vfio_ap_mdev_unregister(void); > >> > >> +static inline int vfio_ap_reset_queue(unsigned int apid, unsigned int apqi, > >> + unsigned int retry) > >> +{ > >> + struct ap_queue_status status; > >> + > >> + do { > >> + status = ap_zapq(AP_MKQID(apid, apqi)); > >> + switch (status.response_code) { > >> + case AP_RESPONSE_NORMAL: > >> + return 0; > >> + case AP_RESPONSE_RESET_IN_PROGRESS: > >> + case AP_RESPONSE_BUSY: > >> + msleep(20); > >> + break; > >> + default: > >> + pr_warn("%s: error zeroizing %02x.%04x: response code %d\n", > >> + VFIO_AP_MODULE_NAME, apid, apqi, > >> + status.response_code); > > How can we end up here? Does this mean that we just don't know what to > > do with this response, or is this something that should never happen? > > (How much sense does it make to print an error?) > > There are additional response codes that could be returned; for example, > in the case of a catastrophic failure such as: The function can not be > performed because the AP was somehow deconfigured or the functiona > cannot be performed due to a machine check failure that caused the AP > path to be removed. It shouldn't happen, but all are possibilities. > I can get rid of the message and just return -EIO if you prefer. These sound like "ugh, we're broken anyway". Not sure if an additional message would help here much; I'd expect other code to just handle the failure (especially things like machine checks). I would not oppose removing the message :) Maybe add a comment /* things are really broken, give up */ instead? > > > > >> + return -EIO; > >> + } > >> + } while (retry--); > >> + > >> + return -EBUSY; > >> +} > >> + > >> #endif /* _VFIO_AP_PRIVATE_H_ */ > >