bring_map currently fails if one of the entries it's mapping is contigious in GPA but not HVA address space. Introduce a mapped_len parameter so it can handle this, returning the actual mapped length. This will still fail if there's no space left in the sg, but luckily max queue size in use is currently 256, while max sg size is 1024, so we should be OK even is all entries happen to cross a single DIMM boundary. Won't work well with very small DIMM sizes, unfortunately: e.g. this will fail with 4K DIMMs where a single request might span a large number of DIMMs. Let's hope these are uncommon - at least we are not breaking things. Reported-by: Stefan Hajnoczi <stefanha@redhat.com> Reported-by: Igor Mammedov <imammedo@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Tested-by: Igor Mammedov <imammedo@redhat.com> Message-id: 1446047243-3221-2-git-send-email-mst@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
527 lines
16 KiB
C
527 lines
16 KiB
C
/* Copyright 2012 Red Hat, Inc.
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* Copyright IBM, Corp. 2012
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*
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* Based on Linux 2.6.39 vhost code:
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* Copyright (C) 2009 Red Hat, Inc.
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* Copyright (C) 2006 Rusty Russell IBM Corporation
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*
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* Author: Michael S. Tsirkin <mst@redhat.com>
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* Stefan Hajnoczi <stefanha@redhat.com>
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*
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* Inspiration, some code, and most witty comments come from
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* Documentation/virtual/lguest/lguest.c, by Rusty Russell
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*
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* This work is licensed under the terms of the GNU GPL, version 2.
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*/
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#include "trace.h"
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#include "hw/hw.h"
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#include "exec/memory.h"
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#include "exec/address-spaces.h"
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#include "hw/virtio/virtio-access.h"
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#include "hw/virtio/dataplane/vring.h"
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#include "hw/virtio/dataplane/vring-accessors.h"
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#include "qemu/error-report.h"
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/* vring_map can be coupled with vring_unmap or (if you still have the
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* value returned in *mr) memory_region_unref.
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* Returns NULL on failure.
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* Callers that can handle a partial mapping must supply mapped_len pointer to
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* get the actual length mapped.
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* Passing mapped_len == NULL requires either a full mapping or a failure.
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*/
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static void *vring_map(MemoryRegion **mr, hwaddr phys,
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hwaddr len, hwaddr *mapped_len,
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bool is_write)
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{
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MemoryRegionSection section = memory_region_find(get_system_memory(), phys, len);
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uint64_t size;
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if (!section.mr) {
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goto out;
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}
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size = int128_get64(section.size);
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assert(size);
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/* Passing mapped_len == NULL requires either a full mapping or a failure. */
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if (!mapped_len && size < len) {
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goto out;
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}
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if (is_write && section.readonly) {
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goto out;
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}
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if (!memory_region_is_ram(section.mr)) {
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goto out;
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}
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/* Ignore regions with dirty logging, we cannot mark them dirty */
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if (memory_region_get_dirty_log_mask(section.mr)) {
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goto out;
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}
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if (mapped_len) {
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*mapped_len = MIN(size, len);
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}
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*mr = section.mr;
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return memory_region_get_ram_ptr(section.mr) + section.offset_within_region;
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out:
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memory_region_unref(section.mr);
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*mr = NULL;
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return NULL;
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}
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static void vring_unmap(void *buffer, bool is_write)
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{
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ram_addr_t addr;
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MemoryRegion *mr;
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mr = qemu_ram_addr_from_host(buffer, &addr);
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memory_region_unref(mr);
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}
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/* Map the guest's vring to host memory */
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bool vring_setup(Vring *vring, VirtIODevice *vdev, int n)
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{
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struct vring *vr = &vring->vr;
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hwaddr addr;
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hwaddr size;
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void *ptr;
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vring->broken = false;
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vr->num = virtio_queue_get_num(vdev, n);
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addr = virtio_queue_get_desc_addr(vdev, n);
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size = virtio_queue_get_desc_size(vdev, n);
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/* Map the descriptor area as read only */
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ptr = vring_map(&vring->mr_desc, addr, size, NULL, false);
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if (!ptr) {
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error_report("Failed to map 0x%" HWADDR_PRIx " byte for vring desc "
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"at 0x%" HWADDR_PRIx,
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size, addr);
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goto out_err_desc;
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}
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vr->desc = ptr;
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addr = virtio_queue_get_avail_addr(vdev, n);
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size = virtio_queue_get_avail_size(vdev, n);
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/* Add the size of the used_event_idx */
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size += sizeof(uint16_t);
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/* Map the driver area as read only */
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ptr = vring_map(&vring->mr_avail, addr, size, NULL, false);
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if (!ptr) {
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error_report("Failed to map 0x%" HWADDR_PRIx " byte for vring avail "
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"at 0x%" HWADDR_PRIx,
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size, addr);
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goto out_err_avail;
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}
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vr->avail = ptr;
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addr = virtio_queue_get_used_addr(vdev, n);
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size = virtio_queue_get_used_size(vdev, n);
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/* Add the size of the avail_event_idx */
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size += sizeof(uint16_t);
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/* Map the device area as read-write */
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ptr = vring_map(&vring->mr_used, addr, size, NULL, true);
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if (!ptr) {
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error_report("Failed to map 0x%" HWADDR_PRIx " byte for vring used "
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"at 0x%" HWADDR_PRIx,
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size, addr);
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goto out_err_used;
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}
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vr->used = ptr;
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vring->last_avail_idx = virtio_queue_get_last_avail_idx(vdev, n);
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vring->last_used_idx = vring_get_used_idx(vdev, vring);
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vring->signalled_used = 0;
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vring->signalled_used_valid = false;
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trace_vring_setup(virtio_queue_get_ring_addr(vdev, n),
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vring->vr.desc, vring->vr.avail, vring->vr.used);
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return true;
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out_err_used:
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memory_region_unref(vring->mr_avail);
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out_err_avail:
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memory_region_unref(vring->mr_desc);
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out_err_desc:
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vring->broken = true;
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return false;
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}
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void vring_teardown(Vring *vring, VirtIODevice *vdev, int n)
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{
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virtio_queue_set_last_avail_idx(vdev, n, vring->last_avail_idx);
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virtio_queue_invalidate_signalled_used(vdev, n);
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memory_region_unref(vring->mr_desc);
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memory_region_unref(vring->mr_avail);
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memory_region_unref(vring->mr_used);
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}
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/* Disable guest->host notifies */
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void vring_disable_notification(VirtIODevice *vdev, Vring *vring)
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{
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if (!virtio_vdev_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX)) {
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vring_set_used_flags(vdev, vring, VRING_USED_F_NO_NOTIFY);
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}
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}
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/* Enable guest->host notifies
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*
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* Return true if the vring is empty, false if there are more requests.
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*/
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bool vring_enable_notification(VirtIODevice *vdev, Vring *vring)
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{
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if (virtio_vdev_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX)) {
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vring_avail_event(&vring->vr) = vring->vr.avail->idx;
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} else {
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vring_clear_used_flags(vdev, vring, VRING_USED_F_NO_NOTIFY);
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}
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smp_mb(); /* ensure update is seen before reading avail_idx */
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return !vring_more_avail(vdev, vring);
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}
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/* This is stolen from linux/drivers/vhost/vhost.c:vhost_notify() */
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bool vring_should_notify(VirtIODevice *vdev, Vring *vring)
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{
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uint16_t old, new;
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bool v;
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/* Flush out used index updates. This is paired
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* with the barrier that the Guest executes when enabling
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* interrupts. */
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smp_mb();
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if (virtio_vdev_has_feature(vdev, VIRTIO_F_NOTIFY_ON_EMPTY) &&
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unlikely(!vring_more_avail(vdev, vring))) {
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return true;
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}
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if (!virtio_vdev_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX)) {
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return !(vring_get_avail_flags(vdev, vring) &
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VRING_AVAIL_F_NO_INTERRUPT);
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}
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old = vring->signalled_used;
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v = vring->signalled_used_valid;
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new = vring->signalled_used = vring->last_used_idx;
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vring->signalled_used_valid = true;
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if (unlikely(!v)) {
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return true;
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}
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return vring_need_event(virtio_tswap16(vdev, vring_used_event(&vring->vr)),
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new, old);
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}
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static int get_desc(Vring *vring, VirtQueueElement *elem,
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struct vring_desc *desc)
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{
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unsigned *num;
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struct iovec *iov;
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hwaddr *addr;
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MemoryRegion *mr;
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hwaddr len;
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if (desc->flags & VRING_DESC_F_WRITE) {
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num = &elem->in_num;
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iov = &elem->in_sg[*num];
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addr = &elem->in_addr[*num];
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} else {
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num = &elem->out_num;
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iov = &elem->out_sg[*num];
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addr = &elem->out_addr[*num];
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/* If it's an output descriptor, they're all supposed
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* to come before any input descriptors. */
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if (unlikely(elem->in_num)) {
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error_report("Descriptor has out after in");
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return -EFAULT;
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}
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}
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while (desc->len) {
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/* Stop for now if there are not enough iovecs available. */
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if (*num >= VIRTQUEUE_MAX_SIZE) {
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error_report("Invalid SG num: %u", *num);
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return -EFAULT;
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}
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iov->iov_base = vring_map(&mr, desc->addr, desc->len, &len,
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desc->flags & VRING_DESC_F_WRITE);
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if (!iov->iov_base) {
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error_report("Failed to map descriptor addr %#" PRIx64 " len %u",
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(uint64_t)desc->addr, desc->len);
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return -EFAULT;
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}
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/* The MemoryRegion is looked up again and unref'ed later, leave the
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* ref in place. */
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(iov++)->iov_len = len;
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*addr++ = desc->addr;
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desc->len -= len;
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desc->addr += len;
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*num += 1;
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}
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return 0;
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}
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static void copy_in_vring_desc(VirtIODevice *vdev,
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const struct vring_desc *guest,
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struct vring_desc *host)
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{
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host->addr = virtio_ldq_p(vdev, &guest->addr);
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host->len = virtio_ldl_p(vdev, &guest->len);
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host->flags = virtio_lduw_p(vdev, &guest->flags);
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host->next = virtio_lduw_p(vdev, &guest->next);
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}
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static bool read_vring_desc(VirtIODevice *vdev,
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hwaddr guest,
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struct vring_desc *host)
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{
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if (address_space_read(&address_space_memory, guest, MEMTXATTRS_UNSPECIFIED,
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(uint8_t *)host, sizeof *host)) {
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return false;
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}
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host->addr = virtio_tswap64(vdev, host->addr);
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host->len = virtio_tswap32(vdev, host->len);
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host->flags = virtio_tswap16(vdev, host->flags);
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host->next = virtio_tswap16(vdev, host->next);
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return true;
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}
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/* This is stolen from linux/drivers/vhost/vhost.c. */
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static int get_indirect(VirtIODevice *vdev, Vring *vring,
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VirtQueueElement *elem, struct vring_desc *indirect)
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{
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struct vring_desc desc;
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unsigned int i = 0, count, found = 0;
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int ret;
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/* Sanity check */
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if (unlikely(indirect->len % sizeof(desc))) {
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error_report("Invalid length in indirect descriptor: "
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"len %#x not multiple of %#zx",
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indirect->len, sizeof(desc));
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vring->broken = true;
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return -EFAULT;
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}
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count = indirect->len / sizeof(desc);
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/* Buffers are chained via a 16 bit next field, so
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* we can have at most 2^16 of these. */
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if (unlikely(count > USHRT_MAX + 1)) {
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error_report("Indirect buffer length too big: %d", indirect->len);
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vring->broken = true;
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return -EFAULT;
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}
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do {
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/* Translate indirect descriptor */
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if (!read_vring_desc(vdev, indirect->addr + found * sizeof(desc),
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&desc)) {
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error_report("Failed to read indirect descriptor "
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"addr %#" PRIx64 " len %zu",
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(uint64_t)indirect->addr + found * sizeof(desc),
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sizeof(desc));
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vring->broken = true;
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return -EFAULT;
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}
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/* Ensure descriptor has been loaded before accessing fields */
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barrier(); /* read_barrier_depends(); */
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if (unlikely(++found > count)) {
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error_report("Loop detected: last one at %u "
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"indirect size %u", i, count);
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vring->broken = true;
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return -EFAULT;
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}
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if (unlikely(desc.flags & VRING_DESC_F_INDIRECT)) {
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error_report("Nested indirect descriptor");
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vring->broken = true;
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return -EFAULT;
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}
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ret = get_desc(vring, elem, &desc);
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if (ret < 0) {
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vring->broken |= (ret == -EFAULT);
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return ret;
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}
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i = desc.next;
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} while (desc.flags & VRING_DESC_F_NEXT);
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return 0;
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}
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static void vring_unmap_element(VirtQueueElement *elem)
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{
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int i;
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/* This assumes that the iovecs, if changed, are never moved past
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* the end of the valid area. This is true if iovec manipulations
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* are done with iov_discard_front and iov_discard_back.
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*/
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for (i = 0; i < elem->out_num; i++) {
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vring_unmap(elem->out_sg[i].iov_base, false);
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}
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for (i = 0; i < elem->in_num; i++) {
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vring_unmap(elem->in_sg[i].iov_base, true);
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}
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}
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/* This looks in the virtqueue and for the first available buffer, and converts
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* it to an iovec for convenient access. Since descriptors consist of some
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* number of output then some number of input descriptors, it's actually two
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* iovecs, but we pack them into one and note how many of each there were.
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*
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* This function returns the descriptor number found, or vq->num (which is
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* never a valid descriptor number) if none was found. A negative code is
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* returned on error.
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*
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* Stolen from linux/drivers/vhost/vhost.c.
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*/
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int vring_pop(VirtIODevice *vdev, Vring *vring,
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VirtQueueElement *elem)
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{
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struct vring_desc desc;
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unsigned int i, head, found = 0, num = vring->vr.num;
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uint16_t avail_idx, last_avail_idx;
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int ret;
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/* Initialize elem so it can be safely unmapped */
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elem->in_num = elem->out_num = 0;
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/* If there was a fatal error then refuse operation */
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if (vring->broken) {
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ret = -EFAULT;
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goto out;
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}
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/* Check it isn't doing very strange things with descriptor numbers. */
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last_avail_idx = vring->last_avail_idx;
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avail_idx = vring_get_avail_idx(vdev, vring);
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barrier(); /* load indices now and not again later */
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if (unlikely((uint16_t)(avail_idx - last_avail_idx) > num)) {
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error_report("Guest moved used index from %u to %u",
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last_avail_idx, avail_idx);
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ret = -EFAULT;
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goto out;
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}
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/* If there's nothing new since last we looked. */
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if (avail_idx == last_avail_idx) {
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ret = -EAGAIN;
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goto out;
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}
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/* Only get avail ring entries after they have been exposed by guest. */
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smp_rmb();
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/* Grab the next descriptor number they're advertising, and increment
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* the index we've seen. */
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head = vring_get_avail_ring(vdev, vring, last_avail_idx % num);
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elem->index = head;
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/* If their number is silly, that's an error. */
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if (unlikely(head >= num)) {
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error_report("Guest says index %u > %u is available", head, num);
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ret = -EFAULT;
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goto out;
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}
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i = head;
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do {
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if (unlikely(i >= num)) {
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error_report("Desc index is %u > %u, head = %u", i, num, head);
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ret = -EFAULT;
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goto out;
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}
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if (unlikely(++found > num)) {
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error_report("Loop detected: last one at %u vq size %u head %u",
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i, num, head);
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ret = -EFAULT;
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goto out;
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}
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copy_in_vring_desc(vdev, &vring->vr.desc[i], &desc);
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/* Ensure descriptor is loaded before accessing fields */
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barrier();
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if (desc.flags & VRING_DESC_F_INDIRECT) {
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ret = get_indirect(vdev, vring, elem, &desc);
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if (ret < 0) {
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goto out;
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}
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continue;
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}
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ret = get_desc(vring, elem, &desc);
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if (ret < 0) {
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goto out;
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}
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i = desc.next;
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} while (desc.flags & VRING_DESC_F_NEXT);
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/* On success, increment avail index. */
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vring->last_avail_idx++;
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if (virtio_vdev_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX)) {
|
|
vring_avail_event(&vring->vr) =
|
|
virtio_tswap16(vdev, vring->last_avail_idx);
|
|
}
|
|
|
|
return head;
|
|
|
|
out:
|
|
assert(ret < 0);
|
|
if (ret == -EFAULT) {
|
|
vring->broken = true;
|
|
}
|
|
vring_unmap_element(elem);
|
|
return ret;
|
|
}
|
|
|
|
/* After we've used one of their buffers, we tell them about it.
|
|
*
|
|
* Stolen from linux/drivers/vhost/vhost.c.
|
|
*/
|
|
void vring_push(VirtIODevice *vdev, Vring *vring, VirtQueueElement *elem,
|
|
int len)
|
|
{
|
|
unsigned int head = elem->index;
|
|
uint16_t new;
|
|
|
|
vring_unmap_element(elem);
|
|
|
|
/* Don't touch vring if a fatal error occurred */
|
|
if (vring->broken) {
|
|
return;
|
|
}
|
|
|
|
/* The virtqueue contains a ring of used buffers. Get a pointer to the
|
|
* next entry in that used ring. */
|
|
vring_set_used_ring_id(vdev, vring, vring->last_used_idx % vring->vr.num,
|
|
head);
|
|
vring_set_used_ring_len(vdev, vring, vring->last_used_idx % vring->vr.num,
|
|
len);
|
|
|
|
/* Make sure buffer is written before we update index. */
|
|
smp_wmb();
|
|
|
|
new = ++vring->last_used_idx;
|
|
vring_set_used_idx(vdev, vring, new);
|
|
if (unlikely((int16_t)(new - vring->signalled_used) < (uint16_t)1)) {
|
|
vring->signalled_used_valid = false;
|
|
}
|
|
}
|