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Wed, 09 Sep 2026 10:54:27 -0700 (PDT) X-Received: by 2002:a05:6a20:2d2c:b0:3d3:adad:f173 with SMTP id adf61e73a8af0-3dabb270ed0mr12635021637.21.1788976466966; Wed, 09 Sep 2026 10:54:26 -0700 (PDT) Received: from localhost ([50.35.44.179]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-3339ac24d7esm72009935eec.15.2026.09.09.10.54.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 09 Sep 2026 10:54:26 -0700 (PDT) Date: Wed, 9 Sep 2026 10:54:20 -0700 From: Jonathan Cameron To: Nicolin Chen Cc: , , , , , , , , , , , , , , , , , , Subject: Re: [PATCH v3 06/13] iommu/arm-smmu-v3: Submit CMDQ_OP_PRI_RESP for IOPF event Message-ID: <20260909105420.00000abe@oss.qualcomm.com> In-Reply-To: References: <9280aea7ae7197eca3f223ef5b998aa25afb29d6.1788222485.git.nicolinc@nvidia.com> <178846311317.1308030.4335813024474016483.b4-review@b4> Organization: Qualcomm X-Mailer: Claws Mail 4.4.0 (GTK 3.24.51; x86_64-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Proofpoint-Spam-Info: AW1haW4tMjYwOTA5MDE5OSBTYWx0ZWRfX9Wx9WFs1Z54x jNersPM0NwNUxrmoClF+qs2cTJKYpdT0GJmiI+xzBqOfjpBGIKdOU4tMORrnA3RvPqQ5iyxiIs0 9BUjLPLsFKHfzwEFWukZ2VhGkwOf8lQ= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTA5MDE5OSBTYWx0ZWRfXwPhWRrxkulu3 pizlxZO4xf3kmth7PpE4/FCC6UoJkIvFWHLOLbzYj26KOgmnImodnhrktlS3UchMRacIZldzXeP 7KrOtkm8N13/GbcvXSJxa24/wXEdiNlYfQvAMQfaiLRG33zvKVYPbBQ0OOAh2Z4JxRb8MfrXjkx EhIEvkBOfSwHa/JYkzs7WKHEXhboGUQw/2NJvQ7iWgo7T8TlQTb3Omg7v/JxicjVGqkqoHmglgQ MJyijynJ6YeDpSuY6kkKc36EgUpnfNC1ngslXysF06I3O8rQ3k8s+2vdA1UsbTa7IpQgJpz1V+4 ItWi2EHOeA/9rXaYvDpCgGKcUL6yX7xiJ9ue47VUphlvTskTjf8Subvfv0cxrZtv3YTu4yZ9igO 5VMXc0XiNPBUMIM+oeXpEthvw2pIPYUd5aEy/c2kXpA+CU/aEBBBASQdgiAuvvw43uaj5V07Nv5 Sc7MSdMbpseQ/+GY+jQ== X-Authority-Analysis: v=2.4 cv=UeFhjqSN c=1 sm=1 tr=0 ts=6aa19d55 cx=c_pps a=Oh5Dbbf/trHjhBongsHeRQ==:117 a=aNnz9XPx1a4JIXSYt2cE/A==:17 a=kj9zAlcOel0A:10 a=VdqzKS8jKosA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=gowsoOTTUOVcmtlkKump:22 a=Ikd4Dj_1AAAA:8 a=9koHXFDKl-DiS4GoSb4A:9 a=CjuIK1q_8ugA:10 a=_Vgx9l1VpLgwpw_dHYaR:22 X-Proofpoint-ORIG-GUID: LTuidf2F0qb_LjcXJlg9Yn17hldzkT-q X-Proofpoint-GUID: LTuidf2F0qb_LjcXJlg9Yn17hldzkT-q X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-09-08_03,2026-09-09_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 clxscore=1015 phishscore=0 lowpriorityscore=0 bulkscore=0 priorityscore=1501 malwarescore=0 adultscore=0 impostorscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2609090199 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260909_105431_396365_411811DC X-CRM114-Status: GOOD ( 22.51 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, 4 Sep 2026 18:15:37 -0700 Nicolin Chen wrote: > On Thu, Sep 03, 2026 at 12:18:33PM -0700, Jonathan Cameron wrote: > > > To handle IOMMU_FAULT_PAGE_REQ from the PRI queue, arm_smmu_page_response() > > > must issue a CMDQ_OP_PRI_RESP back to the SMMU. > > > > > > A stall event in the EVTQ and a PRI request in the PRIQ both surface to the > > > IOPF infrastructure with fault.type == IOMMU_FAULT_PAGE_REQ. SMMUv3 forbids > > > the Stall model on PCIe streams (PCIe must use Terminate), and PRI is only > > > > There are those systems that annoy some because they smell like PCIe > > (present PCIe software interfaces) but aren't and use stall mode. However, it > > is nonsense to use PRI with stall mode. So, instead I'd just argue that for > > stall the fault handling is done synchronously from a device point of > > view so a PRI request makes no sense rather htan associating this with > > PCIe as such. > > I changed the paragraph to: > > A stall event in the EVTQ and a PRI request in the PRIQ both surface to the > IOPF infrastructure with fault.type == IOMMU_FAULT_PAGE_REQ. Yet, both two > models are alternatives: a stalling master resolves a fault synchronously, > holding the transaction until a CMDQ_OP_RESUME, so it has no reason to also > issue a page request. A later change refuses PRI on a stall_enabled master, > so the two will never co-occur. arm_smmu_page_response() can therefore key > on the master state: CMDQ_OP_RESUME for stall_enabled, CMDQ_OP_PRI_RESP for > pri_enabled, mapping IOMMU_PAGE_RESP_* to the PRI response codes. > Nice.