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

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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/20250313130321.898592817@linutronix.de
This commit is contained in:
Thomas Gleixner
2025-03-13 14:03:50 +01:00
parent b9db8df433
commit 79273d0a40
1 changed files with 1 additions and 43 deletions
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44
drivers/pci/tph.c
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@@ -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);