PCI: dwc: Fix MSI page leakage in suspend/resume

Currently, dw_pcie_msi_init() allocates and maps page for msi, then
program the PCIE_MSI_ADDR_LO and PCIE_MSI_ADDR_HI. The Root Complex
may lose power during suspend-to-RAM, so when we resume, we want to
redo the latter but not the former. If designware based driver (for
example, pcie-tegra194.c) calls dw_pcie_msi_init() in resume path, the
msi page will be leaked.

As pointed out by Rob and Ard, there's no need to allocate a page for
the MSI address, we could use an address in the driver data.

To avoid map the MSI msg again during resume, we move the map MSI msg
from dw_pcie_msi_init() to dw_pcie_host_init().

Suggested-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20201009155505.5a580ef5@xhacker.debian
Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Rob Herring <robh@kernel.org>

drivers/pci/controller/dwc/pci-dra7xx.c

@@ -466,7 +466,9 @@ static struct irq_chip dra7xx_pci_msi_bottom_irq_chip = {
 static int dra7xx_pcie_msi_host_init(struct pcie_port *pp)
 {
 	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
+	struct device *dev = pci->dev;
 	u32 ctrl, num_ctrls;
+	int ret;
 
 	pp->msi_irq_chip = &dra7xx_pci_msi_bottom_irq_chip;
 
@@ -482,7 +484,21 @@ static int dra7xx_pcie_msi_host_init(struct pcie_port *pp)
 				    ~0);
 	}
 
-	return dw_pcie_allocate_domains(pp);
+	ret = dw_pcie_allocate_domains(pp);
+	if (ret)
+		return ret;
+
+	pp->msi_data = dma_map_single_attrs(dev, &pp->msi_msg,
+					   sizeof(pp->msi_msg),
+					   DMA_FROM_DEVICE,
+					   DMA_ATTR_SKIP_CPU_SYNC);
+	ret = dma_mapping_error(dev, pp->msi_data);
+	if (ret) {
+		dev_err(dev, "Failed to map MSI data\n");
+		pp->msi_data = 0;
+		dw_pcie_free_msi(pp);
+	}
+	return ret;
 }
 
 static const struct dw_pcie_host_ops dra7xx_pcie_host_ops = {

drivers/pci/controller/dwc/pcie-designware-host.c

@@ -266,30 +266,23 @@ void dw_pcie_free_msi(struct pcie_port *pp)
 	irq_domain_remove(pp->msi_domain);
 	irq_domain_remove(pp->irq_domain);
 
-	if (pp->msi_page)
+	if (pp->msi_data) {
-		__free_page(pp->msi_page);
+		struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
+		struct device *dev = pci->dev;
+
+		dma_unmap_single_attrs(dev, pp->msi_data, sizeof(pp->msi_msg),
+				       DMA_FROM_DEVICE, DMA_ATTR_SKIP_CPU_SYNC);
+	}
 }
 
 void dw_pcie_msi_init(struct pcie_port *pp)
 {
 	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
-	struct device *dev = pci->dev;
+	u64 msi_target = (u64)pp->msi_data;
-	u64 msi_target;
 
 	if (!IS_ENABLED(CONFIG_PCI_MSI))
 		return;
 
-	pp->msi_page = alloc_page(GFP_KERNEL);
-	pp->msi_data = dma_map_page(dev, pp->msi_page, 0, PAGE_SIZE,
-				    DMA_FROM_DEVICE);
-	if (dma_mapping_error(dev, pp->msi_data)) {
-		dev_err(dev, "Failed to map MSI data\n");
-		__free_page(pp->msi_page);
-		pp->msi_page = NULL;
-		return;
-	}
-	msi_target = (u64)pp->msi_data;
-
 	/* Program the msi_data */
 	dw_pcie_writel_dbi(pci, PCIE_MSI_ADDR_LO, lower_32_bits(msi_target));
 	dw_pcie_writel_dbi(pci, PCIE_MSI_ADDR_HI, upper_32_bits(msi_target));
@@ -394,6 +387,16 @@ int dw_pcie_host_init(struct pcie_port *pp)
 				irq_set_chained_handler_and_data(pp->msi_irq,
 							    dw_chained_msi_isr,
 							    pp);
+
+			pp->msi_data = dma_map_single_attrs(pci->dev, &pp->msi_msg,
+						      sizeof(pp->msi_msg),
+						      DMA_FROM_DEVICE,
+						      DMA_ATTR_SKIP_CPU_SYNC);
+			if (dma_mapping_error(pci->dev, pp->msi_data)) {
+				dev_err(pci->dev, "Failed to map MSI data\n");
+				pp->msi_data = 0;
+				goto err_free_msi;
+			}
 		} else {
 			ret = pp->ops->msi_host_init(pp);
 			if (ret < 0)

drivers/pci/controller/dwc/pcie-designware.h

@@ -190,8 +190,8 @@ struct pcie_port {
 	int			msi_irq;
 	struct irq_domain	*irq_domain;
 	struct irq_domain	*msi_domain;
+	u16			msi_msg;
 	dma_addr_t		msi_data;
-	struct page		*msi_page;
 	struct irq_chip		*msi_irq_chip;
 	u32			num_vectors;
 	u32			irq_mask[MAX_MSI_CTRLS];