Commit 71296eae authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

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: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Link: https://lore.kernel.org/all/20250319105506.744271447@linutronix.de
parent d5124a99

drivers/pci/tph.c

+1 −43
Original line number Diff line number Diff line
@@ -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);