PCI/TPH: Replace the broken MSI-X control word update

The driver walks the MSI descriptors to test whether a descriptor exists
for a given index. That's just abuse of the MSI internals.

The same test can be done with a single function call by looking up whether
there is a Linux interrupt number assigned at the index.

What's worse is that the function is completely unserialized against
modifications of the MSI-X control by operations issued from the interrupt
core. It also brings the PCI/MSI-X internal cached control word out of
sync.

Remove the trainwreck and invoke the function provided by the PCI/MSI core
to update it.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://lore.kernel.org/all/20250319105506.744271447@linutronix.de

diff --git a/drivers/pci/tph.c b/drivers/pci/tph.c
index 07de59ca2ebfa6999e9d9f07a03b716cbb268795..77fce5e1b830bf6aa413fe27e0ae7d0cbe274950 100644 (file)
--- a/drivers/pci/tph.c
+++ b/drivers/pci/tph.c
@@ -204,48 +204,6 @@ static u8 get_rp_completer_type(struct pci_dev *pdev)
        return FIELD_GET(PCI_EXP_DEVCAP2_TPH_COMP_MASK, reg);
 }
 
-/* Write ST to MSI-X vector control reg - Return 0 if OK, otherwise -errno */
-static int write_tag_to_msix(struct pci_dev *pdev, int msix_idx, u16 tag)
-{
-#ifdef CONFIG_PCI_MSI
-       struct msi_desc *msi_desc = NULL;
-       void __iomem *vec_ctrl;
-       u32 val;
-       int err = 0;
-
-       msi_lock_descs(&pdev->dev);
-
-       /* Find the msi_desc entry with matching msix_idx */
-       msi_for_each_desc(msi_desc, &pdev->dev, MSI_DESC_ASSOCIATED) {
-               if (msi_desc->msi_index == msix_idx)
-                       break;
-       }
-
-       if (!msi_desc) {
-               err = -ENXIO;
-               goto err_out;
-       }
-
-       /* Get the vector control register (offset 0xc) pointed by msix_idx */
-       vec_ctrl = pdev->msix_base + msix_idx * PCI_MSIX_ENTRY_SIZE;
-       vec_ctrl += PCI_MSIX_ENTRY_VECTOR_CTRL;
-
-       val = readl(vec_ctrl);
-       val &= ~PCI_MSIX_ENTRY_CTRL_ST;
-       val |= FIELD_PREP(PCI_MSIX_ENTRY_CTRL_ST, tag);
-       writel(val, vec_ctrl);
-
-       /* Read back to flush the update */
-       val = readl(vec_ctrl);
-
-err_out:
-       msi_unlock_descs(&pdev->dev);
-       return err;
-#else
-       return -ENODEV;
-#endif
-}
-
 /* Write tag to ST table - Return 0 if OK, otherwise -errno */
 static int write_tag_to_st_table(struct pci_dev *pdev, int index, u16 tag)
 {
@@ -346,7 +304,7 @@ int pcie_tph_set_st_entry(struct pci_dev *pdev, unsigned int index, u16 tag)
 
        switch (loc) {
        case PCI_TPH_LOC_MSIX:
-               err = write_tag_to_msix(pdev, index, tag);
+               err = pci_msix_write_tph_tag(pdev, index, tag);
                break;
        case PCI_TPH_LOC_CAP:
                err = write_tag_to_st_table(pdev, index, tag);