[Qemu-devel] [PATCH v2 1/6] msix: Add simple BAR allocation MSIX setup functions

[Alex Williamson <alex.williamson@redhat.com>]

msi_init() takes over a BAR without really specifying or allowing
specification of how it does so.  Instead, let's split it into
two interfaces, one fully specified, and one trivially easy.  This
implements the latter.  msix_init_exclusive_bar() takes over
allocating and filling a PCI BAR _exclusively_ for the use of MSIX.
When used, the matching msi_uninit_exclusive_bar() should be used
to tear it down.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---

 hw/msix.c |   43 +++++++++++++++++++++++++++++++++++++++++++
 hw/msix.h |    3 +++
 hw/pci.h  |    2 ++
 3 files changed, 48 insertions(+)

diff --git a/hw/msix.c b/hw/msix.c
index b64f109..a4cdfb0 100644
--- a/hw/msix.c
+++ b/hw/msix.c
@@ -299,6 +299,41 @@ err_config:
     return ret;
 }
 
+int msix_init_exclusive_bar(PCIDevice *dev, unsigned short nentries,
+                            uint8_t bar_nr)
+{
+    int ret;
+    char *name;
+
+    /*
+     * Migration compatibility dictates that this remains a 4k
+     * BAR with the vector table in the lower half and PBA in
+     * the upper half.
+     */
+    if (nentries * PCI_MSIX_ENTRY_SIZE > 2048) {
+        return -EINVAL;
+    }
+
+    if (asprintf(&name, "%s MSIX BAR", dev->name) == -1) {
+        return -ENOMEM;
+    }
+
+    memory_region_init(&dev->msix_exclusive_bar, name, 4096);
+
+    free(name);
+
+    ret = msix_init(dev, nentries, &dev->msix_exclusive_bar, bar_nr, 4096);
+    if (ret) {
+        memory_region_destroy(&dev->msix_exclusive_bar);
+        return ret;
+    }
+
+    pci_register_bar(dev, bar_nr, PCI_BASE_ADDRESS_SPACE_MEMORY,
+                     &dev->msix_exclusive_bar);
+
+    return 0;
+}
+
 static void msix_free_irq_entries(PCIDevice *dev)
 {
     int vector;
@@ -329,6 +364,14 @@ int msix_uninit(PCIDevice *dev, MemoryRegion *bar)
     return 0;
 }
 
+void msix_uninit_exclusive_bar(PCIDevice *dev)
+{
+    if (msix_present(dev)) {
+        msix_uninit(dev, &dev->msix_exclusive_bar);
+        memory_region_destroy(&dev->msix_exclusive_bar);
+    }
+}
+
 void msix_save(PCIDevice *dev, QEMUFile *f)
 {
     unsigned n = dev->msix_entries_nr;
diff --git a/hw/msix.h b/hw/msix.h
index e5a488d..bed6bfb 100644
--- a/hw/msix.h
+++ b/hw/msix.h
@@ -7,11 +7,14 @@
 int msix_init(PCIDevice *pdev, unsigned short nentries,
               MemoryRegion *bar,
               unsigned bar_nr, unsigned bar_size);
+int msix_init_exclusive_bar(PCIDevice *dev, unsigned short nentries,
+                            uint8_t bar_nr);
 
 void msix_write_config(PCIDevice *pci_dev, uint32_t address,
                        uint32_t val, int len);
 
 int msix_uninit(PCIDevice *d, MemoryRegion *bar);
+void msix_uninit_exclusive_bar(PCIDevice *dev);
 
 unsigned int msix_nr_vectors_allocated(const PCIDevice *dev);
 
diff --git a/hw/pci.h b/hw/pci.h
index 4c96268..d517a54 100644
--- a/hw/pci.h
+++ b/hw/pci.h
@@ -226,6 +226,8 @@ struct PCIDevice {
 
     /* Space to store MSIX table */
     uint8_t *msix_table_page;
+    /* MemoryRegion container for msix exclusive BAR setup */
+    MemoryRegion msix_exclusive_bar;
     /* MMIO index used to map MSIX table and pending bit entries. */
     MemoryRegion msix_mmio;
     /* Reference-count for entries actually in use by driver. */