re-work API for adding capabilities (#200)

Allow to add capabilities individually, including extended capabilities, and
those to be handled via the region callback.

As a side effect, rework config space accesses to handle reads that straddle
capabilities and non-standard areas and use callbacks as needed.

Signed-off-by: John Levon <john.levon@nutanix.com>
Reviewed-by: Swapnil Ingle <swapnil.ingle@nutanix.com>
Reviewed-by: Thanos Makatos <thanos.makatos@nutanix.com>

1 files changed, 76 insertions, 0 deletions

diff --git a/lib/pci_caps.h b/lib/pci_caps.h
new file mode 100644
index 0000000..86448de
--- /dev/null
+++ b/lib/pci_caps.h
@@ -0,0 +1,76 @@
+/*
+ * Copyright (c) 2019 Nutanix Inc. All rights reserved.
+ *
+ * Authors: Thanos Makatos <thanos@nutanix.com>
+ *          Swapnil Ingle <swapnil.ingle@nutanix.com>
+ *          Felipe Franciosi <felipe@nutanix.com>
+ *
+ *  Redistribution and use in source and binary forms, with or without
+ *  modification, are permitted provided that the following conditions are met:
+ *      * Redistributions of source code must retain the above copyright
+ *        notice, this list of conditions and the following disclaimer.
+ *      * Redistributions in binary form must reproduce the above copyright
+ *        notice, this list of conditions and the following disclaimer in the
+ *        documentation and/or other materials provided with the distribution.
+ *      * Neither the name of Nutanix nor the names of its contributors may be
+ *        used to endorse or promote products derived from this software without
+ *        specific prior written permission.
+ *
+ *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ *  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ *  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ *  ARE DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
+ *  DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ *  (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ *  SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ *  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ *  LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ *  OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
+ *  DAMAGE.
+ *
+ */
+
+#ifndef LIB_VFIO_USER_PCI_CAPS_H
+#define LIB_VFIO_USER_PCI_CAPS_H
+
+#include "libvfio-user.h"
+
+/*
+ * This is an arbitrary value, but more than enough for max caps in extended
+ * config space.
+ */
+#define VFU_MAX_CAPS (1024)
+
+struct pci_cap;
+
+typedef ssize_t (cap_write_cb_t)(vfu_ctx_t *vfu_ctx, struct pci_cap *cap,
+                                 char *buf, size_t count, loff_t offset);
+
+struct pci_cap {
+    const char *name;
+    uint8_t id;
+    size_t off;
+    size_t hdr_size;
+    size_t size;
+    unsigned int flags;
+    cap_write_cb_t *cb;
+};
+
+/*
+ * Return the first cap (if any) that intersects with the [off, off+count)
+ * interval.
+ */
+struct pci_cap *
+cap_find_by_offset(vfu_ctx_t *ctx, loff_t off, size_t count);
+
+/*
+ * Handle an access to a capability.  The access is guaranteed to be entirely
+ * within a capability.
+ */
+ssize_t
+pci_cap_access(vfu_ctx_t *ctx, char *buf, size_t count, loff_t offset,
+               bool is_write);
+
+#endif /* LIB_VFIO_USER_PCI_CAPS_H */
+
+/* ex: set tabstop=4 shiftwidth=4 softtabstop=4 expandtab: */