[patch V2 16/19] PCI/MSI: Deobfuscate virtual MSI-X

Thomas Gleixner
2021-07-29T22:35:27Z

Handling of virtual MSI-X is obfuscated by letting pci_msix_desc_addr()
return NULL and checking the pointer.

Just use msi_desc::msi_attrib.is_virtual at the call sites and get rid of
that pointer check.

No functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
V2: New patch
---
drivers/pci/msi.c | 25 ++++++++-----------------
1 file changed, 8 insertions(+), 17 deletions(-)

--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -166,11 +166,7 @@ static void msi_mask_irq(struct msi_desc

static void __iomem *pci_msix_desc_addr(struct msi_desc *desc)
{
- if (desc->msi_attrib.is_virtual)
- return NULL;
-
- return desc->mask_base +
- desc->msi_attrib.entry_nr * PCI_MSIX_ENTRY_SIZE;
+ return desc->mask_base + desc->msi_attrib.entry_nr * PCI_MSIX_ENTRY_SIZE;
}

/*
@@ -182,14 +178,10 @@ static void __iomem *pci_msix_desc_addr(
*/
static u32 __pci_msix_desc_mask_irq(struct msi_desc *desc, u32 flag)
{
+ void __iomem *desc_addr = pci_msix_desc_addr(desc);
u32 ctrl = desc->msix_ctrl;
- void __iomem *desc_addr;
-
- if (pci_msi_ignore_mask)
- return 0;

- desc_addr = pci_msix_desc_addr(desc);
- if (!desc_addr)
+ if (pci_msi_ignore_mask || desc->msi_attrib.is_virtual)
return 0;

ctrl &= ~PCI_MSIX_ENTRY_CTRL_MASKBIT;
@@ -256,10 +248,8 @@ void __pci_read_msi_msg(struct msi_desc
if (entry->msi_attrib.is_msix) {
void __iomem *base = pci_msix_desc_addr(entry);

- if (!base) {
- WARN_ON(1);
+ if (WARN_ON_ONCE(entry->msi_attrib.is_virtual))
return;
- }

msg->address_lo = readl(base + PCI_MSIX_ENTRY_LOWER_ADDR);
msg->address_hi = readl(base + PCI_MSIX_ENTRY_UPPER_ADDR);
@@ -292,7 +282,7 @@ void __pci_write_msi_msg(struct msi_desc
void __iomem *base = pci_msix_desc_addr(entry);
bool unmasked = !(entry->msix_ctrl & PCI_MSIX_ENTRY_CTRL_MASKBIT);

- if (!base)
+ if (entry->msi_attrib.is_virtual)
goto skip;

/*
@@ -744,9 +734,10 @@ 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)
+ if (!entry->msi_attrib.is_virtual) {
+ addr = pci_msix_desc_addr(entry);
entry->msix_ctrl = readl(addr + PCI_MSIX_ENTRY_VECTOR_CTRL);
+ }

list_add_tail(&entry->list, dev_to_msi_list(&dev->dev));
if (masks)