From c412ba47b2ec4c75e1ef84f39f898cfdec0630ad Mon Sep 17 00:00:00 2001 From: David Woodhouse Date: Sun, 1 Jan 2023 21:31:37 +0000 Subject: 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 Reviewed-by: Paul Durrant --- hw/xen/xen-bus.c | 112 ++++--------------------------------------------------- 1 file changed, 8 insertions(+), 104 deletions(-) (limited to 'hw/xen/xen-bus.c') diff --git a/hw/xen/xen-bus.c b/hw/xen/xen-bus.c index d0b1ae9..b247e86 100644 --- a/hw/xen/xen-bus.c +++ b/hw/xen/xen-bus.c @@ -947,7 +947,7 @@ static void xen_device_frontend_destroy(XenDevice *xendev) void xen_device_set_max_grant_refs(XenDevice *xendev, unsigned int nr_refs, Error **errp) { - if (xengnttab_set_max_grants(xendev->xgth, nr_refs)) { + if (qemu_xen_gnttab_set_max_grants(xendev->xgth, nr_refs)) { error_setg_errno(errp, errno, "xengnttab_set_max_grants failed"); } } @@ -956,9 +956,8 @@ void *xen_device_map_grant_refs(XenDevice *xendev, uint32_t *refs, unsigned int nr_refs, int prot, Error **errp) { - void *map = xengnttab_map_domain_grant_refs(xendev->xgth, nr_refs, - xendev->frontend_id, refs, - prot); + void *map = qemu_xen_gnttab_map_refs(xendev->xgth, nr_refs, + xendev->frontend_id, refs, prot); if (!map) { error_setg_errno(errp, errno, @@ -971,109 +970,17 @@ void *xen_device_map_grant_refs(XenDevice *xendev, uint32_t *refs, void xen_device_unmap_grant_refs(XenDevice *xendev, void *map, unsigned int nr_refs, Error **errp) { - if (xengnttab_unmap(xendev->xgth, map, nr_refs)) { + if (qemu_xen_gnttab_unmap(xendev->xgth, map, nr_refs)) { error_setg_errno(errp, errno, "xengnttab_unmap failed"); } } -static void compat_copy_grant_refs(XenDevice *xendev, bool to_domain, - XenDeviceGrantCopySegment segs[], - unsigned int nr_segs, Error **errp) -{ - uint32_t *refs = g_new(uint32_t, nr_segs); - int prot = to_domain ? PROT_WRITE : PROT_READ; - void *map; - unsigned int i; - - for (i = 0; i < nr_segs; i++) { - XenDeviceGrantCopySegment *seg = &segs[i]; - - refs[i] = to_domain ? seg->dest.foreign.ref : - seg->source.foreign.ref; - } - - map = xengnttab_map_domain_grant_refs(xendev->xgth, nr_segs, - xendev->frontend_id, refs, - prot); - if (!map) { - error_setg_errno(errp, errno, - "xengnttab_map_domain_grant_refs failed"); - goto done; - } - - for (i = 0; i < nr_segs; i++) { - XenDeviceGrantCopySegment *seg = &segs[i]; - void *page = map + (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->xgth, map, nr_segs)) { - error_setg_errno(errp, errno, "xengnttab_unmap failed"); - } - -done: - g_free(refs); -} - void xen_device_copy_grant_refs(XenDevice *xendev, bool to_domain, XenDeviceGrantCopySegment segs[], unsigned int nr_segs, Error **errp) { - xengnttab_grant_copy_segment_t *xengnttab_segs; - unsigned int i; - - if (!xendev->feature_grant_copy) { - compat_copy_grant_refs(xendev, to_domain, segs, nr_segs, errp); - return; - } - - xengnttab_segs = g_new0(xengnttab_grant_copy_segment_t, nr_segs); - - for (i = 0; i < nr_segs; i++) { - XenDeviceGrantCopySegment *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 = xendev->frontend_id; - 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 = xendev->frontend_id; - 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; - } - - if (xengnttab_grant_copy(xendev->xgth, nr_segs, xengnttab_segs)) { - error_setg_errno(errp, errno, "xengnttab_grant_copy failed"); - goto done; - } - - for (i = 0; i < nr_segs; i++) { - xengnttab_grant_copy_segment_t *xengnttab_seg = &xengnttab_segs[i]; - - if (xengnttab_seg->status != GNTST_okay) { - error_setg(errp, "xengnttab_grant_copy seg[%u] failed", i); - break; - } - } - -done: - g_free(xengnttab_segs); + qemu_xen_gnttab_grant_copy(xendev->xgth, to_domain, xendev->frontend_id, + (XenGrantCopySegment *)segs, nr_segs, errp); } struct XenEventChannel { @@ -1235,7 +1142,7 @@ static void xen_device_unrealize(DeviceState *dev) xen_device_backend_destroy(xendev); if (xendev->xgth) { - xengnttab_close(xendev->xgth); + qemu_xen_gnttab_close(xendev->xgth); xendev->xgth = NULL; } @@ -1298,15 +1205,12 @@ static void xen_device_realize(DeviceState *dev, Error **errp) xendev->watch_list = watch_list_create(xendev->xsh); - xendev->xgth = xengnttab_open(NULL, 0); + xendev->xgth = qemu_xen_gnttab_open(); if (!xendev->xgth) { error_setg_errno(errp, errno, "failed xengnttab_open"); goto unrealize; } - xendev->feature_grant_copy = - (xengnttab_grant_copy(xendev->xgth, 0, NULL) == 0); - xen_device_backend_create(xendev, errp); if (*errp) { goto unrealize; -- cgit v1.1