[RFC PATCH 3/5] pci/msix: Implement PBA writes

[Nicholas Piggin <npiggin@gmail.com>]

Implement PBA write 1 to trigger and 0 to clear. This is used by
qtests which mask the MSI irq and so the bits remain pending and
expect to be cleared with stores.

Some devices like e1000e seem to have MSIX PBA pending tied to
some device state level, as such they call msix_clr_pending()
directly, and clearing pending via a store to PBA causes this
to go out of synch. So the qpci_msix_pending() function is
changed to avoid clearing, and a new test-and-clear function is
added for tests that would like to clear.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 tests/qtest/libqos/pci.h |  1 +
 hw/pci/msix.c            | 16 ++++++++++++++++
 tests/qtest/libqos/pci.c | 21 ++++++++++++++++++---
 3 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/tests/qtest/libqos/pci.h b/tests/qtest/libqos/pci.h
index 5a7b2454ad..de540f7803 100644
--- a/tests/qtest/libqos/pci.h
+++ b/tests/qtest/libqos/pci.h
@@ -94,6 +94,7 @@ uint8_t qpci_find_capability(QPCIDevice *dev, uint8_t id, uint8_t start_addr);
 void qpci_msix_enable(QPCIDevice *dev);
 void qpci_msix_disable(QPCIDevice *dev);
 bool qpci_msix_pending(QPCIDevice *dev, uint16_t entry);
+bool qpci_msix_test_clear_pending(QPCIDevice *dev, uint16_t entry);
 bool qpci_msix_masked(QPCIDevice *dev, uint16_t entry);
 uint16_t qpci_msix_table_size(QPCIDevice *dev);
 
diff --git a/hw/pci/msix.c b/hw/pci/msix.c
index 487e49834e..b16b03b888 100644
--- a/hw/pci/msix.c
+++ b/hw/pci/msix.c
@@ -260,6 +260,22 @@ static uint64_t msix_pba_mmio_read(void *opaque, hwaddr addr,
 static void msix_pba_mmio_write(void *opaque, hwaddr addr,
                                 uint64_t val, unsigned size)
 {
+    PCIDevice *dev = opaque;
+    unsigned vector_start = addr * 8;
+    unsigned vector_end = MIN(addr + size * 8, dev->msix_entries_nr);
+    unsigned i;
+
+    for (i = vector_start; i < vector_end; i++) {
+        if ((val >> i) & 1) {
+            if (!msix_is_pending(dev, i)) {
+                msix_notify(dev, i);
+            }
+        } else {
+            if (msix_is_pending(dev, i)) {
+                msix_clr_pending(dev, i);
+            }
+        }
+    }
 }
 
 static const MemoryRegionOps msix_pba_mmio_ops = {
diff --git a/tests/qtest/libqos/pci.c b/tests/qtest/libqos/pci.c
index 45199c7dc4..6726c401cc 100644
--- a/tests/qtest/libqos/pci.c
+++ b/tests/qtest/libqos/pci.c
@@ -343,11 +343,26 @@ bool qpci_msix_pending(QPCIDevice *dev, uint16_t entry)
 
     g_assert(dev->msix_enabled);
     pba_entry = qpci_io_readl(dev, dev->msix_pba_bar, dev->msix_pba_off + off);
-    qpci_io_writel(dev, dev->msix_pba_bar, dev->msix_pba_off + off,
-                   pba_entry & ~(1 << bit_n));
-    return (pba_entry & (1 << bit_n)) != 0;
+    return (pba_entry & (1 << bit_n));
 }
 
+bool qpci_msix_test_clear_pending(QPCIDevice *dev, uint16_t entry)
+{
+    uint32_t pba_entry;
+    uint8_t bit_n = entry % 32;
+    uint64_t  off = (entry / 32) * PCI_MSIX_ENTRY_SIZE / 4;
+
+    g_assert(dev->msix_enabled);
+    pba_entry = qpci_io_readl(dev, dev->msix_pba_bar, dev->msix_pba_off + off);
+    if (pba_entry & (1 << bit_n)) {
+        qpci_io_writel(dev, dev->msix_pba_bar, dev->msix_pba_off + off,
+                       pba_entry & ~(1 << bit_n));
+        return true;
+    }
+    return false;
+}
+
+
 bool qpci_msix_masked(QPCIDevice *dev, uint16_t entry)
 {
     uint8_t addr;
-- 
2.45.2