[RFC PATCH 2/5] qtest/libqos/pci: Fix msix_enable sharing bar0

[Nicholas Piggin <npiggin@gmail.com>]

Devices where the MSI-X addresses are shared with other MMIO on BAR0
can not use msi_enable because it unmaps and remaps BAR0, which
interferes with device MMIO mappings. xhci-nec is one such device we
would like to test msix with.

Keep track of each the BAR iomaps for each device and add code in msix
to use existing iomap if the msix bars are already mapped.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 tests/qtest/libqos/pci.h |  1 +
 tests/qtest/libqos/pci.c | 22 ++++++++++++++++------
 2 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/tests/qtest/libqos/pci.h b/tests/qtest/libqos/pci.h
index 9dc82ea723..5a7b2454ad 100644
--- a/tests/qtest/libqos/pci.h
+++ b/tests/qtest/libqos/pci.h
@@ -68,6 +68,7 @@ struct QPCIDevice
     bool bars_mapped[6];
     QPCIBar bars[6];
     bool msix_enabled;
+    bool msix_table_bar_iomap, msix_pba_bar_iomap;
     QPCIBar msix_table_bar, msix_pba_bar;
     uint64_t msix_table_off, msix_pba_off;
 };
diff --git a/tests/qtest/libqos/pci.c b/tests/qtest/libqos/pci.c
index a42ca08261..45199c7dc4 100644
--- a/tests/qtest/libqos/pci.c
+++ b/tests/qtest/libqos/pci.c
@@ -288,15 +288,21 @@ void qpci_msix_enable(QPCIDevice *dev)
 
     table = qpci_config_readl(dev, addr + PCI_MSIX_TABLE);
     bir_table = table & PCI_MSIX_FLAGS_BIRMASK;
-    dev->msix_table_bar = qpci_iomap(dev, bir_table, NULL);
+    if (dev->bars_mapped[bir_table]) {
+        dev->msix_table_bar = dev->bars[bir_table];
+    } else {
+        dev->msix_table_bar_iomap = true;
+        dev->msix_table_bar = qpci_iomap(dev, bir_table, NULL);
+    }
     dev->msix_table_off = table & ~PCI_MSIX_FLAGS_BIRMASK;
 
     table = qpci_config_readl(dev, addr + PCI_MSIX_PBA);
     bir_pba = table & PCI_MSIX_FLAGS_BIRMASK;
-    if (bir_pba != bir_table) {
-        dev->msix_pba_bar = qpci_iomap(dev, bir_pba, NULL);
+    if (dev->bars_mapped[bir_pba]) {
+        dev->msix_pba_bar = dev->bars[bir_pba];
     } else {
-        dev->msix_pba_bar = dev->msix_table_bar;
+        dev->msix_pba_bar_iomap = true;
+        dev->msix_pba_bar = qpci_iomap(dev, bir_pba, NULL);
     }
     dev->msix_pba_off = table & ~PCI_MSIX_FLAGS_BIRMASK;
 
@@ -315,10 +321,14 @@ void qpci_msix_disable(QPCIDevice *dev)
     qpci_config_writew(dev, addr + PCI_MSIX_FLAGS,
                                                 val & ~PCI_MSIX_FLAGS_ENABLE);
 
-    if (dev->msix_pba_bar.addr != dev->msix_table_bar.addr) {
+    if (dev->msix_pba_bar_iomap) {
+        dev->msix_pba_bar_iomap = false;
         qpci_iounmap(dev, dev->msix_pba_bar);
     }
-    qpci_iounmap(dev, dev->msix_table_bar);
+    if (dev->msix_table_bar_iomap) {
+        dev->msix_table_bar_iomap = false;
+        qpci_iounmap(dev, dev->msix_table_bar);
+    }
 
     dev->msix_enabled = 0;
     dev->msix_table_off = 0;
-- 
2.45.2