hw/xen: Add gnttab operations to allow redirection to internal emulation
Move the existing code using libxengnttab to xen-operations.c and allow
the operations to be redirected so that we can add emulation of grant
table mapping for backend drivers.
In emulation, mapping more than one grant ref to be virtually contiguous
would be fairly difficult. The best way to do it might be to make the
ram_block mappings actually backed by a file (shmem or a deleted file,
perhaps) so that we can have multiple *shared* mappings of it. But that
would be fairly intrusive.
Making the backend drivers cope with page *lists* instead of expecting
the mapping to be contiguous is also non-trivial, since some structures
would actually *cross* page boundaries (e.g. the 32-bit blkif responses
which are 12 bytes).
So for now, we'll support only single-page mappings in emulation. Add a
XEN_GNTTAB_OP_FEATURE_MAP_MULTIPLE flag to indicate that the native Xen
implementation *does* support multi-page maps, and a helper function to
query it.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
diff --git a/hw/xen/xen-legacy-backend.c b/hw/xen/xen-legacy-backend.c
index 9ce3dc2..1e9a28f 100644
--- a/hw/xen/xen-legacy-backend.c
+++ b/hw/xen/xen-legacy-backend.c
@@ -43,7 +43,6 @@
const char *xen_protocol;
/* private */
-static bool xen_feature_grant_copy;
static int debug;
int xenstore_write_be_str(struct XenLegacyDevice *xendev, const char *node,
@@ -113,7 +112,7 @@
{
assert(xendev->ops->flags & DEVOPS_FLAG_NEED_GNTDEV);
- if (xengnttab_set_max_grants(xendev->gnttabdev, nr_refs)) {
+ if (qemu_xen_gnttab_set_max_grants(xendev->gnttabdev, nr_refs)) {
xen_pv_printf(xendev, 0, "xengnttab_set_max_grants failed: %s\n",
strerror(errno));
}
@@ -126,8 +125,8 @@
assert(xendev->ops->flags & DEVOPS_FLAG_NEED_GNTDEV);
- ptr = xengnttab_map_domain_grant_refs(xendev->gnttabdev, nr_refs,
- xen_domid, refs, prot);
+ ptr = qemu_xen_gnttab_map_refs(xendev->gnttabdev, nr_refs, xen_domid, refs,
+ prot);
if (!ptr) {
xen_pv_printf(xendev, 0,
"xengnttab_map_domain_grant_refs failed: %s\n",
@@ -142,119 +141,27 @@
{
assert(xendev->ops->flags & DEVOPS_FLAG_NEED_GNTDEV);
- if (xengnttab_unmap(xendev->gnttabdev, ptr, nr_refs)) {
+ if (qemu_xen_gnttab_unmap(xendev->gnttabdev, ptr, nr_refs)) {
xen_pv_printf(xendev, 0, "xengnttab_unmap failed: %s\n",
strerror(errno));
}
}
-static int compat_copy_grant_refs(struct XenLegacyDevice *xendev,
- bool to_domain,
- XenGrantCopySegment segs[],
- unsigned int nr_segs)
-{
- uint32_t *refs = g_new(uint32_t, nr_segs);
- int prot = to_domain ? PROT_WRITE : PROT_READ;
- void *pages;
- unsigned int i;
-
- for (i = 0; i < nr_segs; i++) {
- XenGrantCopySegment *seg = &segs[i];
-
- refs[i] = to_domain ?
- seg->dest.foreign.ref : seg->source.foreign.ref;
- }
-
- pages = xengnttab_map_domain_grant_refs(xendev->gnttabdev, nr_segs,
- xen_domid, refs, prot);
- if (!pages) {
- xen_pv_printf(xendev, 0,
- "xengnttab_map_domain_grant_refs failed: %s\n",
- strerror(errno));
- g_free(refs);
- return -1;
- }
-
- for (i = 0; i < nr_segs; i++) {
- XenGrantCopySegment *seg = &segs[i];
- void *page = pages + (i * XC_PAGE_SIZE);
-
- if (to_domain) {
- memcpy(page + seg->dest.foreign.offset, seg->source.virt,
- seg->len);
- } else {
- memcpy(seg->dest.virt, page + seg->source.foreign.offset,
- seg->len);
- }
- }
-
- if (xengnttab_unmap(xendev->gnttabdev, pages, nr_segs)) {
- xen_pv_printf(xendev, 0, "xengnttab_unmap failed: %s\n",
- strerror(errno));
- }
-
- g_free(refs);
- return 0;
-}
-
int xen_be_copy_grant_refs(struct XenLegacyDevice *xendev,
bool to_domain,
XenGrantCopySegment segs[],
unsigned int nr_segs)
{
- xengnttab_grant_copy_segment_t *xengnttab_segs;
- unsigned int i;
int rc;
assert(xendev->ops->flags & DEVOPS_FLAG_NEED_GNTDEV);
- if (!xen_feature_grant_copy) {
- return compat_copy_grant_refs(xendev, to_domain, segs, nr_segs);
- }
-
- xengnttab_segs = g_new0(xengnttab_grant_copy_segment_t, nr_segs);
-
- for (i = 0; i < nr_segs; i++) {
- XenGrantCopySegment *seg = &segs[i];
- xengnttab_grant_copy_segment_t *xengnttab_seg = &xengnttab_segs[i];
-
- if (to_domain) {
- xengnttab_seg->flags = GNTCOPY_dest_gref;
- xengnttab_seg->dest.foreign.domid = xen_domid;
- xengnttab_seg->dest.foreign.ref = seg->dest.foreign.ref;
- xengnttab_seg->dest.foreign.offset = seg->dest.foreign.offset;
- xengnttab_seg->source.virt = seg->source.virt;
- } else {
- xengnttab_seg->flags = GNTCOPY_source_gref;
- xengnttab_seg->source.foreign.domid = xen_domid;
- xengnttab_seg->source.foreign.ref = seg->source.foreign.ref;
- xengnttab_seg->source.foreign.offset =
- seg->source.foreign.offset;
- xengnttab_seg->dest.virt = seg->dest.virt;
- }
-
- xengnttab_seg->len = seg->len;
- }
-
- rc = xengnttab_grant_copy(xendev->gnttabdev, nr_segs, xengnttab_segs);
-
+ rc = qemu_xen_gnttab_grant_copy(xendev->gnttabdev, to_domain, xen_domid,
+ segs, nr_segs, NULL);
if (rc) {
- xen_pv_printf(xendev, 0, "xengnttab_copy failed: %s\n",
- strerror(errno));
+ xen_pv_printf(xendev, 0, "xengnttab_grant_copy failed: %s\n",
+ strerror(-rc));
}
-
- for (i = 0; i < nr_segs; i++) {
- xengnttab_grant_copy_segment_t *xengnttab_seg =
- &xengnttab_segs[i];
-
- if (xengnttab_seg->status != GNTST_okay) {
- xen_pv_printf(xendev, 0, "segment[%u] status: %d\n", i,
- xengnttab_seg->status);
- rc = -1;
- }
- }
-
- g_free(xengnttab_segs);
return rc;
}
@@ -466,7 +373,7 @@
}
if (xendev->ops->flags & DEVOPS_FLAG_NEED_GNTDEV) {
- xendev->gnttabdev = xengnttab_open(NULL, 0);
+ xendev->gnttabdev = qemu_xen_gnttab_open();
if (xendev->gnttabdev == NULL) {
xen_pv_printf(NULL, 0, "can't open gnttab device\n");
return -1;
@@ -524,7 +431,7 @@
xendev->ops->disconnect(xendev);
}
if (xendev->gnttabdev) {
- xengnttab_close(xendev->gnttabdev);
+ qemu_xen_gnttab_close(xendev->gnttabdev);
xendev->gnttabdev = NULL;
}
if (xendev->be_state != state) {
@@ -687,8 +594,6 @@
void xen_be_init(void)
{
- xengnttab_handle *gnttabdev;
-
xenstore = xs_daemon_open();
if (!xenstore) {
xen_pv_printf(NULL, 0, "can't connect to xenstored\n");
@@ -697,19 +602,11 @@
qemu_set_fd_handler(xs_fileno(xenstore), xenstore_update, NULL, NULL);
- if (xen_xc == NULL || xen_fmem == NULL) {
+ if (xen_evtchn_ops == NULL || xen_gnttab_ops == NULL) {
xen_pv_printf(NULL, 0, "Xen operations not set up\n");
exit(1);
}
- gnttabdev = xengnttab_open(NULL, 0);
- if (gnttabdev != NULL) {
- if (xengnttab_grant_copy(gnttabdev, 0, NULL) == 0) {
- xen_feature_grant_copy = true;
- }
- xengnttab_close(gnttabdev);
- }
-
xen_sysdev = qdev_new(TYPE_XENSYSDEV);
sysbus_realize_and_unref(SYS_BUS_DEVICE(xen_sysdev), &error_fatal);
xen_sysbus = qbus_new(TYPE_XENSYSBUS, xen_sysdev, "xen-sysbus");
