Since not all devices require a 32-bit MSI address, add support to the
PCIe host driver to allow setting the DMA mask to 64-bits. This allows
kernels to disable ZONE_DMA32 and bounce buffering (swiotlb) without
risking not being able to get a 32-bit address during DMA allocation.
Basically, in the slim chance that there are no 32-bit allocations
available, the current PCIe host driver will fail to allocate the
msi_msg page due to a DMA address overflow (seen in [1]). With this
patch, the PCIe driver can advertise 64-bit support via it's MSI
capabilities to hint to the PCIe host driver to set the DMA mask to
64-bits.
[1] https://lore.kernel.org/all/[email protected]/
Reported-by: kernel test robot <[email protected]>
Signed-off-by: Will McVicker <[email protected]>
---
drivers/pci/controller/dwc/pcie-designware-host.c | 14 ++++++++++++--
drivers/pci/controller/dwc/pcie-designware.c | 9 +++++++++
drivers/pci/controller/dwc/pcie-designware.h | 1 +
3 files changed, 22 insertions(+), 2 deletions(-)
diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index 8f2222f51671..2b9b63489415 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -338,6 +338,8 @@ static int dw_pcie_msi_host_init(struct dw_pcie_rp *pp)
struct platform_device *pdev = to_platform_device(dev);
int ret;
u32 ctrl, num_ctrls;
+ bool msi_64b = false;
+ u16 msi_capabilities;
for (ctrl = 0; ctrl < MAX_MSI_CTRLS; ctrl++)
pp->irq_mask[ctrl] = ~0;
@@ -375,9 +377,17 @@ static int dw_pcie_msi_host_init(struct dw_pcie_rp *pp)
dw_chained_msi_isr, pp);
}
- ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(32));
+ msi_capabilities = dw_pcie_msi_capabilities(pci);
+ if (msi_capabilities & PCI_MSI_FLAGS_ENABLE)
+ msi_64b = msi_capabilities & PCI_MSI_FLAGS_64BIT ? true : false;
+
+ dev_dbg(dev, "Setting MSI DMA mask to %s-bit.\n",
+ msi_64b ? "64" : "32");
+ ret = dma_set_mask_and_coherent(dev, msi_64b ?
+ DMA_BIT_MASK(64) : DMA_BIT_MASK(32));
if (ret)
- dev_warn(dev, "Failed to set DMA mask to 32-bit. Devices with only 32-bit MSI support may not work properly\n");
+ dev_warn(dev, "Failed to set DMA mask to %s-bit.\n",
+ msi_64b ? "64" : "32");
pp->msi_page = dma_alloc_coherent(dev, PAGE_SIZE, &pp->msi_data,
GFP_KERNEL);
diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
index c6725c519a47..8ed402307d7f 100644
--- a/drivers/pci/controller/dwc/pcie-designware.c
+++ b/drivers/pci/controller/dwc/pcie-designware.c
@@ -82,6 +82,15 @@ u8 dw_pcie_find_capability(struct dw_pcie *pci, u8 cap)
}
EXPORT_SYMBOL_GPL(dw_pcie_find_capability);
+u16 dw_pcie_msi_capabilities(struct dw_pcie *pci)
+{
+ u8 offset;
+
+ offset = dw_pcie_find_capability(pci, PCI_CAP_ID_MSI);
+ return dw_pcie_readw_dbi(pci, offset + PCI_MSI_FLAGS);
+}
+EXPORT_SYMBOL_GPL(dw_pcie_msi_capabilities);
+
static u16 dw_pcie_find_next_ext_capability(struct dw_pcie *pci, u16 start,
u8 cap)
{
diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index 09b887093a84..4631e26ba6c5 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -333,6 +333,7 @@ void dw_pcie_version_detect(struct dw_pcie *pci);
u8 dw_pcie_find_capability(struct dw_pcie *pci, u8 cap);
u16 dw_pcie_find_ext_capability(struct dw_pcie *pci, u8 cap);
+u16 dw_pcie_msi_capabilities(struct dw_pcie *pci);
int dw_pcie_read(void __iomem *addr, int size, u32 *val);
int dw_pcie_write(void __iomem *addr, int size, u32 val);
--
2.37.1.559.g78731f0fdb-goog
On Wed, Aug 10, 2022 at 06:35:35PM +0000, Will McVicker wrote:
> Since not all devices require a 32-bit MSI address, add support to the
> PCIe host driver to allow setting the DMA mask to 64-bits. This allows
> kernels to disable ZONE_DMA32 and bounce buffering (swiotlb) without
> risking not being able to get a 32-bit address during DMA allocation.
> Basically, in the slim chance that there are no 32-bit allocations
> available, the current PCIe host driver will fail to allocate the
> msi_msg page due to a DMA address overflow (seen in [1]). With this
> patch, the PCIe driver can advertise 64-bit support via it's MSI
> capabilities to hint to the PCIe host driver to set the DMA mask to
> 64-bits.
>
> [1] https://lore.kernel.org/all/[email protected]/
>
> Reported-by: kernel test robot <[email protected]>
> Signed-off-by: Will McVicker <[email protected]>
> ---
> drivers/pci/controller/dwc/pcie-designware-host.c | 14 ++++++++++++--
> drivers/pci/controller/dwc/pcie-designware.c | 9 +++++++++
> drivers/pci/controller/dwc/pcie-designware.h | 1 +
> 3 files changed, 22 insertions(+), 2 deletions(-)
Reviewed-by: Rob Herring <[email protected]>