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[179.125.193.229]) by smtp.gmail.com with ESMTPSA id a68sm20906352qkc.110.2020.07.13.23.46.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 13 Jul 2020 23:46:34 -0700 (PDT) Message-ID: <846ba63b1f1fc4c9366f39b2cf09df71a19da891.camel@gmail.com> Subject: Re: [PATCH v3 4/6] powerpc/pseries/iommu: Remove default DMA window before creating DDW From: Leonardo Bras To: Alexey Kardashevskiy , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , Thiago Jung Bauermann , Ram Pai Date: Tue, 14 Jul 2020 03:46:29 -0300 In-Reply-To: References: <20200703061844.111865-1-leobras.c@gmail.com> <20200703061844.111865-5-leobras.c@gmail.com> <8c29be499e8741e7d77d53ca005034a2ca0179ac.camel@gmail.com> <18fd94d2-4365-16d1-7c85-af07d5c9a0f3@ozlabs.ru> Organization: IBM Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.34.4 (3.34.4-1.fc31) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" In fact, the changes over the last patch are more complex than the current patch. Just for reference, that's how enable_ddw() currently patches: @@ -1087,7 +1119,7 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn) struct device_node *dn; u32 ddw_avail[DDW_APPLICABLE_SIZE]; struct direct_window *window; - struct property *win64; + struct property *win64, *default_win = NULL; struct dynamic_dma_window_prop *ddwprop; struct failed_ddw_pdn *fpdn; @@ -1133,14 +1165,38 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn) if (ret != 0) goto out_failed; + /* + * If there is no window available, remove the default DMA window, + * if it's present. This will make all the resources available to the + * new DDW window. + * If anything fails after this, we need to restore it, so also check + * for extensions presence. + */ if (query.windows_available == 0) { - /* - * no additional windows are available for this device. - * We might be able to reallocate the existing window, - * trading in for a larger page size. - */ - dev_dbg(&dev->dev, "no free dynamic windows"); - goto out_failed; + int reset_win_ext; + + default_win = of_find_property(pdn, "ibm,dma-window", NULL); + if (!default_win) + goto out_failed; + + reset_win_ext = ddw_read_ext(pdn, DDW_EXT_RESET_DMA_WIN, NULL); + if (reset_win_ext) { + default_win = NULL; + goto out_failed; + } + + remove_dma_window(pdn, ddw_avail, default_win); + + /* Query again, to check if the window is available */ + ret = query_ddw(dev, ddw_avail, &query, pdn); + if (ret != 0) + goto out_failed; + + if (query.windows_available == 0) { + /* no windows are available for this device. */ + dev_dbg(&dev->dev, "no free dynamic windows"); + goto out_failed; + } } if (query.page_size & 4) { page_shift = 24; /* 16MB */ @@ -1231,6 +1287,8 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn) kfree(win64); out_failed: + if (default_win) + reset_dma_window(dev, pdn); fpdn = kzalloc(sizeof(*fpdn), GFP_KERNEL); if (!fpdn)