We can't always support mmap across an entire device region, for
example we deny mmaps covering the MSI-X table of PCI devices, but
we don't really have a way to report it. We expect the user to
implicitly know this restriction. We also can't split the region
because vfio-pci defines an API with fixed region index to BAR
number mapping. We therefore define a new capability which lists
areas within the region that may be mmap'd. In addition to the
MSI-X case, this potentially enables in-kernel emulation and
extensions to devices.
Signed-off-by: Alex Williamson <alex.william...@redhat.com>
---
include/uapi/linux/vfio.h | 26 +++++++++++++++++++++++++-
1 file changed, 25 insertions(+), 1 deletion(-)
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 432569f..d3f6499 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -221,13 +221,37 @@ struct vfio_region_info {
#define VFIO_REGION_INFO_FLAG_READ (1 << 0) /* Region supports read */
#define VFIO_REGION_INFO_FLAG_WRITE (1 << 1) /* Region supports write */
#define VFIO_REGION_INFO_FLAG_MMAP (1 << 2) /* Region supports mmap */
+#define VFIO_REGION_INFO_FLAG_CAPS (1 << 3) /* Info supports caps */
__u32 index; /* Region index */
- __u32 resv; /* Reserved for alignment */
+ __u32 cap_offset; /* Offset within info struct of first cap */
__u64 size; /* Region size (bytes) */
__u64 offset; /* Region offset from start of device fd */
};
#define VFIO_DEVICE_GET_REGION_INFO _IO(VFIO_TYPE, VFIO_BASE + 8)
+/*
+ * The sparse mmap capability allows finer granularity of specifying areas
+ * within a region with mmap support. When specified, the user should only
+ * mmap the offset ranges specified by the areas array. mmaps outside of the
+ * areas specified may fail (such as the range covering a PCI MSI-X table) or
+ * may result in improper device behavior.
+ *
+ * The structures below define version 1 of this capability.
+ */
+#define VFIO_REGION_INFO_CAP_SPARSE_MMAP 1
+
+struct vfio_region_sparse_mmap_area {
+ __u64 offset; /* Offset of mmap'able area within region */
+ __u64 size; /* Size of mmap'able area */
+};
+
+struct vfio_region_info_cap_sparse_mmap {
+ struct vfio_info_cap_header header;
+ __u32 nr_areas;
+ __u32 reserved;
+ struct vfio_region_sparse_mmap_area areas[];
+};
+
/**
* VFIO_DEVICE_GET_IRQ_INFO - _IOWR(VFIO_TYPE, VFIO_BASE + 9,
* struct vfio_irq_info)
--
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