While the parameter 'interrupts' to the functions pci_epc_set_msi() and
pci_epc_set_msix() represent the actual number of interrupts, and
pci_epc_get_msi() and pci_epc_get_msix() return the actual number of
interrupts.
These endpoint library functions just mentioned will however supply
"interrupts - 1" to the EPC callback functions pci_epc_ops->set_msi() and
pci_epc_ops->set_msix(), and likewise add 1 to return value from
pci_epc_ops->get_msi() and pci_epc_ops->get_msix(), even though the
parameter name for the callback function is also named 'interrupts'.
While the set_msix() callback function in pcie-cadence-ep writes the
Table Size field correctly (N-1), the calculation of the PBA offset
is wrong because it calculates space for (N-1) entries instead of N.
This results in e.g. the following error when using QEMU with PCI
passthrough on a device which relies on the PCI endpoint subsystem:
failed to add PCI capability 0x11[0x50]@0xb0: table & pba overlap, or they don't fit in BARs, or don't align
Fix the calculation of PBA offset in the MSI-X capability.
Fixes: 3ef5d16f50f8 ("PCI: cadence: Add MSI-X support to Endpoint driver")
Signed-off-by: Niklas Cassel <cassel@xxxxxxxxxx>
---
drivers/pci/controller/cadence/pcie-cadence-ep.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/pci/controller/cadence/pcie-cadence-ep.c b/drivers/pci/controller/cadence/pcie-cadence-ep.c
index 599ec4b1223e..112ae200b393 100644
--- a/drivers/pci/controller/cadence/pcie-cadence-ep.c
+++ b/drivers/pci/controller/cadence/pcie-cadence-ep.c
@@ -292,13 +292,14 @@ static int cdns_pcie_ep_set_msix(struct pci_epc *epc, u8 fn, u8 vfn,
struct cdns_pcie *pcie = &ep->pcie;
u32 cap = CDNS_PCIE_EP_FUNC_MSIX_CAP_OFFSET;
u32 val, reg;
+ u16 actual_interrupts = interrupts + 1;
fn = cdns_pcie_get_fn_from_vfn(pcie, fn, vfn);
reg = cap + PCI_MSIX_FLAGS;
val = cdns_pcie_ep_fn_readw(pcie, fn, reg);
val &= ~PCI_MSIX_FLAGS_QSIZE;
- val |= interrupts;
+ val |= interrupts; /* 0's based value */
cdns_pcie_ep_fn_writew(pcie, fn, reg, val);
/* Set MSI-X BAR and offset */
@@ -308,7 +309,7 @@ static int cdns_pcie_ep_set_msix(struct pci_epc *epc, u8 fn, u8 vfn,
/* Set PBA BAR and offset. BAR must match MSI-X BAR */
reg = cap + PCI_MSIX_PBA;
- val = (offset + (interrupts * PCI_MSIX_ENTRY_SIZE)) | bir;
+ val = (offset + (actual_interrupts * PCI_MSIX_ENTRY_SIZE)) | bir;
cdns_pcie_ep_fn_writel(pcie, fn, reg, val);
return 0;
--
2.49.0
