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[142.68.80.239]) by smtp.gmail.com with ESMTPSA id qq3-20020a0562142c0300b0068f9c181fc0sm1307321qvb.113.2024.02.21.07.34.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 21 Feb 2024 07:34:38 -0800 (PST) Received: from jgg by wakko with local (Exim 4.95) (envelope-from ) id 1rcocH-00BPeA-Li; Wed, 21 Feb 2024 11:34:37 -0400 Date: Wed, 21 Feb 2024 11:34:37 -0400 From: Jason Gunthorpe To: Lu Baolu Cc: Joerg Roedel , Will Deacon , Robin Murphy , Kevin Tian , Huang Jiaqing , Ethan Zhao , iommu@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 2/2] iommu/vt-d: Use device rbtree in iopf reporting path Message-ID: <20240221153437.GB13491@ziepe.ca> References: <20240220065939.121116-1-baolu.lu@linux.intel.com> <20240220065939.121116-3-baolu.lu@linux.intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240220065939.121116-3-baolu.lu@linux.intel.com> On Tue, Feb 20, 2024 at 02:59:39PM +0800, Lu Baolu wrote: > diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c > index acfe27bd3448..6743fe6c7a36 100644 > --- a/drivers/iommu/intel/iommu.c > +++ b/drivers/iommu/intel/iommu.c > @@ -4430,8 +4430,11 @@ static struct iommu_device *intel_iommu_probe_device(struct device *dev) > static void intel_iommu_release_device(struct device *dev) > { > struct device_domain_info *info = dev_iommu_priv_get(dev); > + struct intel_iommu *iommu = info->iommu; > > + mutex_lock(&iommu->iopf_lock); > device_rbtree_remove(info); > + mutex_unlock(&iommu->iopf_lock); This seems like a pretty reasonable solution, maybe someday it can become lockless.. This is a fast path right? > @@ -691,21 +691,22 @@ static irqreturn_t prq_event_thread(int irq, void *d) > if (unlikely(req->lpig && !req->rd_req && !req->wr_req)) > goto prq_advance; > > - pdev = pci_get_domain_bus_and_slot(iommu->segment, > - PCI_BUS_NUM(req->rid), > - req->rid & 0xff); > /* > * If prq is to be handled outside iommu driver via receiver of > * the fault notifiers, we skip the page response here. > */ > - if (!pdev) > + mutex_lock(&iommu->iopf_lock); > + dev = device_rbtree_find(iommu, req->rid); > + if (!dev) { > + mutex_unlock(&iommu->iopf_lock); > goto bad_req; > + } Though now we have a mutex and a spinlock covering the same data structure.. It could be optimized some more. But maybe we should leave micro optimization aside for now. Reviewed-by: Jason Gunthorpe Jason