From bbd8cc516329f84b70d38a75820f36f2ecd0abda Mon Sep 17 00:00:00 2001

From: Alex Williamson <alex.williamson@redhat.com>

Date: Fri, 29 Sep 2017 21:46:14 +0200

Subject: [PATCH 15/27] vfio: Enable sparse mmap capability

RH-Author: Alex Williamson <alex.williamson@redhat.com>

Message-id: <20170929214614.16765.48627.stgit@gimli.home>

Patchwork-id: 76773

O-Subject: [RHEL-7.5 qemu-kvm PATCH 15/16] vfio: Enable sparse mmap capability

Bugzilla: 1494181

RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>

RH-Acked-by: Auger Eric <eric.auger@redhat.com>

RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>

Upstream: b53b0f696b10828f6393155f44a352c019e673fd

RHEL: Roll in required linux-headers update

The sparse mmap capability in a vfio region info allows vfio to tell

us which sub-areas of a region may be mmap'd.  Thus rather than

assuming a single mmap covers the entire region and later frobbing it

ourselves for things like the PCI MSI-X vector table, we can read that

directly from vfio.

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

Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>

Tested-by: Gerd Hoffmann <kraxel@redhat.com>

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 hw/misc/vfio.c             | 67 +++++++++++++++++++++++++++++++++++++++++++---

 linux-headers/linux/vfio.h | 53 +++++++++++++++++++++++++++++++++++-

 trace-events               |  2 ++

 3 files changed, 117 insertions(+), 5 deletions(-)

diff --git a/hw/misc/vfio.c b/hw/misc/vfio.c

index d634531..a27698b 100644

--- a/hw/misc/vfio.c

+++ b/hw/misc/vfio.c

@@ -2602,6 +2602,54 @@ static void vfio_unmap_bar(VFIOPCIDevice *vdev, int nr)

     vfio_region_finalize(&bar->region);

 }

+static struct vfio_info_cap_header *

+vfio_get_region_info_cap(struct vfio_region_info *info, uint16_t id)

+{

+    struct vfio_info_cap_header *hdr;

+    void *ptr = info;

+

+    if (!(info->flags & VFIO_REGION_INFO_FLAG_CAPS)) {

+        return NULL;

+    }

+

+    for (hdr = ptr + info->cap_offset; hdr != ptr; hdr = ptr + hdr->next) {

+        if (hdr->id == id) {

+            return hdr;

+        }

+    }

+

+    return NULL;

+}

+

+static void vfio_setup_region_sparse_mmaps(VFIORegion *region,

+                                           struct vfio_region_info *info)

+{

+    struct vfio_info_cap_header *hdr;

+    struct vfio_region_info_cap_sparse_mmap *sparse;

+    int i;

+

+    hdr = vfio_get_region_info_cap(info, VFIO_REGION_INFO_CAP_SPARSE_MMAP);

+    if (!hdr) {

+        return;

+    }

+

+    sparse = container_of(hdr, struct vfio_region_info_cap_sparse_mmap, header);

+

+    trace_vfio_region_sparse_mmap_header(region->vbasedev->name,

+                                         region->nr, sparse->nr_areas);

+

+    region->nr_mmaps = sparse->nr_areas;

+    region->mmaps = g_new0(VFIOMmap, region->nr_mmaps);

+

+    for (i = 0; i < region->nr_mmaps; i++) {

+        region->mmaps[i].offset = sparse->areas[i].offset;

+        region->mmaps[i].size = sparse->areas[i].size;

+        trace_vfio_region_sparse_mmap_entry(i, region->mmaps[i].offset,

+                                            region->mmaps[i].offset +

+                                            region->mmaps[i].size);

+    }

+}

+

 static int vfio_region_setup(Object *obj, VFIODevice *vbasedev,

                              VFIORegion *region, int index, const char *name)

 {

@@ -2628,11 +2676,14 @@ static int vfio_region_setup(Object *obj, VFIODevice *vbasedev,

             region->flags & VFIO_REGION_INFO_FLAG_MMAP &&

             !(region->size & ~TARGET_PAGE_MASK)) {

-            region->nr_mmaps = 1;

-            region->mmaps = g_new0(VFIOMmap, region->nr_mmaps);

+            vfio_setup_region_sparse_mmaps(region, info);

-            region->mmaps[0].offset = 0;

-            region->mmaps[0].size = region->size;

+            if (!region->nr_mmaps) {

+                region->nr_mmaps = 1;

+                region->mmaps = g_new0(VFIOMmap, region->nr_mmaps);

+                region->mmaps[0].offset = 0;

+                region->mmaps[0].size = region->size;

+            }

         }

     }

@@ -3796,6 +3847,7 @@ static int vfio_get_region_info(VFIODevice *vbasedev, int index,

     *info = g_malloc0(argsz);

     (*info)->index = index;

+retry:

     (*info)->argsz = argsz;

     if (ioctl(vbasedev->fd, VFIO_DEVICE_GET_REGION_INFO, *info)) {

@@ -3803,6 +3855,13 @@ static int vfio_get_region_info(VFIODevice *vbasedev, int index,

         return -errno;

     }

+    if ((*info)->argsz > argsz) {

+        argsz = (*info)->argsz;

+        *info = g_realloc(*info, argsz);

+

+        goto retry;

+    }

+

     return 0;

 }

diff --git a/linux-headers/linux/vfio.h b/linux-headers/linux/vfio.h

index d197fd4..8995a34 100644

--- a/linux-headers/linux/vfio.h

+++ b/linux-headers/linux/vfio.h

@@ -38,6 +38,33 @@

 #define VFIO_TYPE	(';')

 #define VFIO_BASE	100

+/*

+ * For extension of INFO ioctls, VFIO makes use of a capability chain

+ * designed after PCI/e capabilities.  A flag bit indicates whether

+ * this capability chain is supported and a field defined in the fixed

+ * structure defines the offset of the first capability in the chain.

+ * This field is only valid when the corresponding bit in the flags

+ * bitmap is set.  This offset field is relative to the start of the

+ * INFO buffer, as is the next field within each capability header.

+ * The id within the header is a shared address space per INFO ioctl,

+ * while the version field is specific to the capability id.  The

+ * contents following the header are specific to the capability id.

+ */

+struct vfio_info_cap_header {

+	__u16	id;		/* Identifies capability */

+	__u16	version;	/* Version specific to the capability ID */

+	__u32	next;		/* Offset of next capability */

+};

+

+/*

+ * Callers of INFO ioctls passing insufficiently sized buffers will see

+ * the capability chain flag bit set, a zero value for the first capability

+ * offset (if available within the provided argsz), and argsz will be

+ * updated to report the necessary buffer size.  For compatibility, the

+ * INFO ioctl will not report error in this case, but the capability chain

+ * will not be available.

+ */

+

 /* -------- IOCTLs for VFIO file descriptor (/dev/vfio/vfio) -------- */

 /**

@@ -171,13 +198,37 @@ 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)

diff --git a/trace-events b/trace-events

index cc62b0b..fa2618d 100644

--- a/trace-events

+++ b/trace-events

@@ -1164,3 +1164,5 @@ vfio_region_mmap(const char *name, unsigned long offset, unsigned long end) "Reg

 vfio_region_exit(const char *name, int index) "Device %s, region %d"

 vfio_region_finalize(const char *name, int index) "Device %s, region %d"

 vfio_region_mmaps_set_enabled(const char *name, bool enabled) "Region %s mmaps enabled: %d"

+vfio_region_sparse_mmap_header(const char *name, int index, int nr_areas) "Device %s region %d: %d sparse mmap entries"

+vfio_region_sparse_mmap_entry(int i, unsigned long start, unsigned long end) "sparse entry %d [0x%lx - 0x%lx]"

-- 

1.8.3.1