[PATCH 11/11] PCI: endpoint: test: Do not relocate fixed MSI-X tables

[Manikanta Maddireddy]

Some endpoint controllers expose MSI-X table/PBA storage at fixed,
hardware-owned BARs. Such BARs are described to endpoint functions as
BAR_RESERVED with PCI_EPC_BAR_RSVD_MSIX_TBL_RAM, so the function driver
must not reprogram the MSI-X Table/PBA capability to point into ordinary
function BAR memory.

pci_epf_test always allocates MSI-X storage after its test registers and
calls pci_epc_set_msix(). On controllers with fixed MSI-X storage, this
overwrites the controller-defined MSI-X layout. For example, the generic
DesignWare path derives the PBA offset from the number of vectors, which
can make the host program the wrong MSI-X storage and prevent MSI-X
delivery.

Detect fixed MSI-X table BARs and leave the controller-owned MSI-X
capability layout unchanged. Keep allocating and programming MSI-X
storage in the test BAR only for controllers that do not advertise fixed
MSI-X table storage.

Signed-off-by: Manikanta Maddireddy <mmaddireddy@xxxxxxxxxx>
---
 drivers/pci/endpoint/functions/pci-epf-test.c | 27 +++++++++++++++++--
 1 file changed, 25 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
index d4905aa8e4c0..82d4714e998c 100644
--- a/drivers/pci/endpoint/functions/pci-epf-test.c
+++ b/drivers/pci/endpoint/functions/pci-epf-test.c
@@ -83,6 +83,7 @@ struct pci_epf_test {
 	struct config_group	group;
 	enum pci_barno		test_reg_bar;
 	size_t			msix_table_offset;
+	bool			msix_table_fixed;
 	struct delayed_work	cmd_handler;
 	struct dma_chan		*dma_chan_tx;
 	struct dma_chan		*dma_chan_rx;
@@ -98,6 +99,26 @@ struct pci_epf_test {
 	size_t			bar_size[PCI_STD_NUM_BARS];
 };
 
+static bool pci_epf_test_msix_table_fixed(const struct pci_epc_features *features)
+{
+	enum pci_barno bar;
+	int i;
+
+	for (bar = BAR_0; bar < PCI_STD_NUM_BARS; bar++) {
+		const struct pci_epc_bar_desc *desc = &features->bar[bar];
+
+		if (desc->type != BAR_RESERVED)
+			continue;
+
+		for (i = 0; i < desc->nr_rsvd_regions; i++) {
+			if (desc->rsvd_regions[i].type == PCI_EPC_BAR_RSVD_MSIX_TBL_RAM)
+				return true;
+		}
+	}
+
+	return false;
+}
+
 struct pci_epf_test_reg {
 	__le32 magic;
 	__le32 command;
@@ -1214,7 +1235,7 @@ static int pci_epf_test_epc_init(struct pci_epf *epf)
 		}
 	}
 
-	if (epc_features->msix_capable) {
+	if (epc_features->msix_capable && !epf_test->msix_table_fixed) {
 		ret = pci_epc_set_msix(epc, epf->func_no, epf->vfunc_no,
 				       epf->msix_interrupts,
 				       epf_test->test_reg_bar,
@@ -1282,7 +1303,9 @@ static int pci_epf_test_alloc_space(struct pci_epf *epf)
 
 	test_reg_bar_size = ALIGN(sizeof(struct pci_epf_test_reg), 128);
 
-	if (epc_features->msix_capable) {
+	epf_test->msix_table_fixed = pci_epf_test_msix_table_fixed(epc_features);
+
+	if (epc_features->msix_capable && !epf_test->msix_table_fixed) {
 		msix_table_size = PCI_MSIX_ENTRY_SIZE * epf->msix_interrupts;
 		epf_test->msix_table_offset = test_reg_bar_size;
 		/* Align to QWORD or 8 Bytes */
-- 
2.34.1