PCI: dwc: ep: Correct PBA offset in .set_msix() callback

While dw_pcie_ep_set_msix() 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 the following QEMU error when using 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.

[bhelgaas: more specific subject and commit log]

Fixes: 83153d9f36e2 ("PCI: endpoint: Fix ->set_msix() to take BIR and offset as arguments")
Signed-off-by: Niklas Cassel <cassel@kernel.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Wilfred Mallawa <wilfred.mallawa@wdc.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20250514074313.283156-9-cassel@kernel.org

diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
index 1a0bf9341542eabc4d28070e3a2d6a8b0b444578..24026f3f34133bf70be7d5bfb7337c3d0d3447e8 100644 (file)
--- a/drivers/pci/controller/dwc/pcie-designware-ep.c
+++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
@@ -585,6 +585,7 @@ static int dw_pcie_ep_set_msix(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
        struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
        struct dw_pcie_ep_func *ep_func;
        u32 val, reg;
+       u16 actual_interrupts = interrupts + 1;
 
        ep_func = dw_pcie_ep_get_func_from_ep(ep, func_no);
        if (!ep_func || !ep_func->msix_cap)
@@ -595,7 +596,7 @@ static int dw_pcie_ep_set_msix(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
        reg = ep_func->msix_cap + PCI_MSIX_FLAGS;
        val = dw_pcie_ep_readw_dbi(ep, func_no, reg);
        val &= ~PCI_MSIX_FLAGS_QSIZE;
-       val |= interrupts;
+       val |= interrupts; /* 0's based value */
        dw_pcie_writew_dbi(pci, reg, val);
 
        reg = ep_func->msix_cap + PCI_MSIX_TABLE;
@@ -603,7 +604,7 @@ static int dw_pcie_ep_set_msix(struct pci_epc *epc, u8 func_no, u8 vfunc_no,
        dw_pcie_ep_writel_dbi(ep, func_no, reg, val);
 
        reg = ep_func->msix_cap + PCI_MSIX_PBA;
-       val = (offset + (interrupts * PCI_MSIX_ENTRY_SIZE)) | bir;
+       val = (offset + (actual_interrupts * PCI_MSIX_ENTRY_SIZE)) | bir;
        dw_pcie_ep_writel_dbi(ep, func_no, reg, val);
 
        dw_pcie_dbi_ro_wr_dis(pci);