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Fri, 24 Jul 2026 17:13:15 +0000 (GMT) Received: from [9.61.177.4] (unknown [9.61.177.4]) by smtpav04.wdc07v.mail.ibm.com (Postfix) with ESMTP; Fri, 24 Jul 2026 17:13:15 +0000 (GMT) Message-ID: Date: Fri, 24 Jul 2026 13:13:14 -0400 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 4/8] s390/vfio_ccw: ensure first IDAW remains constant To: Eric Farman , linux-s390@vger.kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Halil Pasic , Christian Borntraeger , stable@vger.kernel.org References: <20260723174751.1180334-1-farman@linux.ibm.com> <20260723174751.1180334-5-farman@linux.ibm.com> Content-Language: en-US From: Matthew Rosato In-Reply-To: <20260723174751.1180334-5-farman@linux.ibm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Info: AW1haW4tMjYwNzI0MDE1NSBTYWx0ZWRfX6+rr17PtpO/q MO2NqkYSWw1Y2ekZ44iQKV0ZbEU1U3oHx9bCRe1IKBn26IWllOlRggeiqZALwB/IXCNeI8zJBQU 4VyuObvGVLa1/IePlTvJYLoXYKzzFxw= X-Proofpoint-ORIG-GUID: Rn8U8E625vYrD7R7oeh4JQdOvaS6ZaP5 X-Proofpoint-GUID: Rn8U8E625vYrD7R7oeh4JQdOvaS6ZaP5 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzI0MDE1NSBTYWx0ZWRfX19e5epe/JRYc EBuSkqAYbTpqjTmA3iNGb+jyQZUpxciHV9e2YwTrxu32lbHCp9ml++k+tv/fQgjLX30CKc1RKyo c8cuXlGMNeowFXi7Nj1U/OV4StUUEpw7QRijMC6EFUHEqS9fHWDmyCU+OJExjGbYD1yAJ/Fwegk OtOWDqZ5/kk2ahJhxCVlBNfzTAbMShfckDiNPLr46TizsfaEAwNIsyUY7zWTG2tvUieb1nPQh6U W6faOzr0Cq/AzzFex7pXpOtewX+aeQEuocVVv651OF2MLW1RK+XBuPQPbUYaRIgncRaZirPdYV/ HDigDEkG8o24ZJlqOAJgMXiOWTvDatZXTgEZQAlTnPsHHG48xmquiCXSF0p1NK+K+5wuTU9i2Z2 0fgomlyQFunivbIPKLR6UP1clr7y8ToRVlD9ctlih8PKdcqknpp+2rElBwC5wi4NhRYduMmR5kZ jqsfg9uMpBBghx3+v/A== X-Authority-Analysis: v=2.4 cv=du3rzVg4 c=1 sm=1 tr=0 ts=6a639d2f cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=IkcTkHD0fZMA:10 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=ZRtANegDX4hjiLUYKcQA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-24_04,2026-07-24_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 clxscore=1015 malwarescore=0 spamscore=0 impostorscore=0 phishscore=0 bulkscore=0 priorityscore=1501 lowpriorityscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607240155 On 7/23/26 1:47 PM, Eric Farman wrote: > The first IDAW in a list does not need to be on a 2K/4K boundary > like all others, and so is read separately to accurately calculate > the size of the buffer needed to read the full IDAL. > > Verify that the address found in the first IDAW is unchanged between > reads, to ensure a consistent set of IDAWs being worked with. > > Fixes: 01aa26c672c0 ("s390/cio: Combine direct and indirect CCW paths") > Cc: stable@vger.kernel.org > Signed-off-by: Eric Farman > --- > drivers/s390/cio/vfio_ccw_cp.c | 15 +++++++++++++++ > drivers/s390/cio/vfio_ccw_cp.h | 1 + > 2 files changed, 16 insertions(+) > > diff --git a/drivers/s390/cio/vfio_ccw_cp.c b/drivers/s390/cio/vfio_ccw_cp.c > index 258a99930c6a..06b6bc6142a0 100644 > --- a/drivers/s390/cio/vfio_ccw_cp.c > +++ b/drivers/s390/cio/vfio_ccw_cp.c > @@ -533,6 +533,7 @@ static dma64_t *get_guest_idal(struct ccw1 *ccw, struct channel_program *cp, int > &container_of(cp, struct vfio_ccw_private, cp)->vdev; > dma64_t *idaws; > dma32_t *idaws_f1; > + u64 first_idaw; > int idal_len = idaw_nr * sizeof(*idaws); > int idaw_size = idal_is_2k(cp) ? PAGE_SIZE / 2 : PAGE_SIZE; > int idaw_mask = ~(idaw_size - 1); > @@ -549,6 +550,17 @@ static dma64_t *get_guest_idal(struct ccw1 *ccw, struct channel_program *cp, int > kfree(idaws); > return ERR_PTR(ret); > } > + > + if (cp->orb.cmd.c64) > + first_idaw = dma64_to_u64(idaws[0]); > + else > + first_idaw = dma32_to_u32(idaws[0] >> 32); Sashiko mentions this one, since first_idaw is a u64 would first_idaw = dma64_to_u64(idaws[0]) >> 32; work? Then you are doing the >> 32 against a u64 just like what is done in ccw_count_idaws() where we set guest_iova for comparison below. Other than this line, this patch LGTM. > + > + /* Unexpected mismatch from earlier read */ > + if (first_idaw != cp->guest_iova) { > + kfree(idaws); > + return ERR_PTR(-EINVAL); > + } > } else { > /* Fabricate an IDAL based off CCW data address */ > if (cp->orb.cmd.c64) { > @@ -614,6 +626,9 @@ static int ccw_count_idaws(struct ccw1 *ccw, > iova = dma32_to_u32(ccw->cda); > } > > + /* Save the read address for later */ > + cp->guest_iova = iova; > + > /* Format-1 IDAWs operate on 2K each */ > if (!cp->orb.cmd.c64) > return idal_2k_nr_words((void *)iova, bytes); > diff --git a/drivers/s390/cio/vfio_ccw_cp.h b/drivers/s390/cio/vfio_ccw_cp.h > index dc91a317ef19..d547dbc969cc 100644 > --- a/drivers/s390/cio/vfio_ccw_cp.h > +++ b/drivers/s390/cio/vfio_ccw_cp.h > @@ -43,6 +43,7 @@ struct channel_program { > union orb orb; > bool initialized; > struct ccw1 *guest_cp; > + u64 guest_iova; > int ccwchain_count; > }; >