Re: [patch 2/8] PCI/MSI: Mask all unused MSI-X entries

Raj, Ashok
2021-07-21T22:23:45Z

Hi Thomas

On Wed, Jul 21, 2021 at 09:11:28PM +0200, Thomas Gleixner wrote:

[snip]

> --- a/drivers/pci/msi.c
> +++ b/drivers/pci/msi.c
> @@ -691,6 +691,7 @@ static int msix_setup_entries(struct pci
> {
> struct irq_affinity_desc *curmsk, *masks = NULL;
> struct msi_desc *entry;
> + void __iomem *addr;
> int ret, i;
> int vec_count = pci_msix_vec_count(dev);
>
> @@ -711,6 +712,7 @@ static int msix_setup_entries(struct pci
>
> entry->msi_attrib.is_msix = 1;
> entry->msi_attrib.is_64 = 1;
> +
> if (entries)
> entry->msi_attrib.entry_nr = entries[i].entry;
> else
> @@ -722,6 +724,10 @@ static int msix_setup_entries(struct pci
> entry->msi_attrib.default_irq = dev->irq;
> entry->mask_base = base;
>
> + addr = pci_msix_desc_addr(entry);
> + if (addr)
> + entry->masked = readl(addr + PCI_MSIX_ENTRY_VECTOR_CTRL);

Silly question:
Do we have to read what the HW has to set this entry->masked? Shouldn't
this be all masked before we start the setup?

> +
> list_add_tail(&entry->list, dev_to_msi_list(&dev->dev));
> if (masks)
> curmsk++;
> @@ -732,26 +738,25 @@ static int msix_setup_entries(struct pci
> return ret;
> }
>
> -static void msix_program_entries(struct pci_dev *dev,
> - struct msix_entry *entries)
> +static void msix_update_entries(struct pci_dev *dev, struct msix_entry *entries)
> {
> struct msi_desc *entry;
> - int i = 0;
> - void __iomem *desc_addr;
>
> for_each_pci_msi_entry(entry, dev) {
> - if (entries)
> - entries[i++].vector = entry->irq;
> + if (entries) {
> + entries->vector = entry->irq;
> + entries++;
> + }
> + }
> +}
>
> - desc_addr = pci_msix_desc_addr(entry);
> - if (desc_addr)
> - entry->masked = readl(desc_addr +
> - PCI_MSIX_ENTRY_VECTOR_CTRL);
> - else
> - entry->masked = 0;
> +static void msix_mask_all(void __iomem *base, int tsize)
> +{
> + u32 ctrl = PCI_MSIX_ENTRY_CTRL_MASKBIT;
> + int i;
>
> - msix_mask_irq(entry, 1);
> - }
> + for (i = 0; i < tsize; i++, base += PCI_MSIX_ENTRY_SIZE)
> + writel(ctrl, base + PCI_MSIX_ENTRY_VECTOR_CTRL);

shouldn't we initialize entry->masked here?

> }
>
> /**
> @@ -768,9 +773,9 @@ static void msix_program_entries(struct
> static int msix_capability_init(struct pci_dev *dev, struct msix_entry *entries,
> int nvec, struct irq_affinity *affd)
> {
> - int ret;
> - u16 control;
> void __iomem *base;
> + int ret, tsize;
> + u16 control;
>
> /*
> * Some devices require MSI-X to be enabled before the MSI-X
> @@ -782,12 +787,16 @@ static int msix_capability_init(struct p
>
> pci_read_config_word(dev, dev->msix_cap + PCI_MSIX_FLAGS, &control);
> /* Request & Map MSI-X table region */
> - base = msix_map_region(dev, msix_table_size(control));
> + tsize = msix_table_size(control);
> + base = msix_map_region(dev, tsize);
> if (!base) {
> ret = -ENOMEM;
> goto out_disable;
> }
>
> + /* Ensure that all table entries are masked. */
> + msix_mask_all(base, tsize);
> +
> ret = msix_setup_entries(dev, base, entries, nvec, affd);
> if (ret)
> goto out_disable;
> @@ -801,7 +810,7 @@ static int msix_capability_init(struct p
> if (ret)
> goto out_free;
>
> - msix_program_entries(dev, entries);
> + msix_update_entries(dev, entries);
>
> ret = populate_msi_sysfs(dev);
> if (ret)
>

--
Cheers,
Ashok

[Forgiveness is the attribute of the STRONG - Gandhi]