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[34.124.168.21]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-b57c55a33a8sm12092461a12.46.2025.09.29.15.24.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 29 Sep 2025 15:24:13 -0700 (PDT) Date: Mon, 29 Sep 2025 22:24:08 +0000 From: Pranjal Shrivastava To: Daniel Mentz Cc: iommu@lists.linux.dev, linux-kernel@vger.kernel.org, Will Deacon , Mostafa Saleh , Liviu Dudau , Jason Gunthorpe , Rob Clark Subject: Re: [PATCH 1/2] iommu/io-pgtable-arm: Implement .iotlb_sync_map callback Message-ID: References: <20250927223953.936562-1-danielmentz@google.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=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Mon, Sep 29, 2025 at 01:42:29PM -0700, Daniel Mentz wrote: > On Mon, Sep 29, 2025 at 12:57 PM Pranjal Shrivastava wrote: > > > > On Sat, Sep 27, 2025 at 10:39:52PM +0000, Daniel Mentz wrote: > > > +static int __arm_lpae_iotlb_sync_map(struct arm_lpae_io_pgtable *data, unsigned long iova, > > > + size_t size, int lvl, arm_lpae_iopte *ptep) > > > +{ > > > + struct io_pgtable *iop = &data->iop; > > > + size_t block_size = ARM_LPAE_BLOCK_SIZE(lvl, data); > > > + int ret = 0, num_entries, max_entries; > > > + unsigned long iova_offset, sync_idx_start, sync_idx_end; > > > + int i, shift, synced_entries = 0; > > > + > > > + shift = (ARM_LPAE_LVL_SHIFT(lvl - 1, data) + ARM_LPAE_PGD_IDX(lvl - 1, data)); > > > + iova_offset = iova & ((1ULL << shift) - 1); > > > + sync_idx_start = ARM_LPAE_LVL_IDX(iova, lvl, data); > > > + sync_idx_end = (iova_offset + size + block_size - ARM_LPAE_GRANULE(data)) >> > > > + ARM_LPAE_LVL_SHIFT(lvl, data); > > > + max_entries = arm_lpae_max_entries(sync_idx_start, data); > > > + num_entries = min_t(unsigned long, sync_idx_end - sync_idx_start, max_entries); > > > + ptep += sync_idx_start; > > > + > > > + if (lvl < (ARM_LPAE_MAX_LEVELS - 1)) { > > > + for (i = 0; i < num_entries; i++) { > > > + arm_lpae_iopte pte = READ_ONCE(ptep[i]); > > > + unsigned long synced; > > > + > > > + WARN_ON(!pte); > > > + > > > + if (iopte_type(pte) == ARM_LPAE_PTE_TYPE_TABLE) { > > > + int n = i - synced_entries; > > > + > > > + if (n) { > > > + __arm_lpae_sync_pte(&ptep[synced_entries], n, &iop->cfg); > > > + synced_entries += n; > > > + } > > > + ret = __arm_lpae_iotlb_sync_map(data, iova, size, lvl + 1, > > > + iopte_deref(pte, data)); > > > > I think we must check the returned value here and break the loop on > > error. Otherwise, we might burry a failure by continuing the loop. > > We should add something like: > > > > if (ret) > > break; > > > > Now, I'm realising that __arm_lpae_iotlb_sync_map always returns 0, in > which case I could change the return type to void. Would that work for > you? Ah, yes, I just realized that too. I guess we can simply change the return type to void. Thanks, Praan