Let dataplane allocate different region for the desc/avail/used ring regions. Take VIRTIO_RING_F_EVENT_IDX into account to increase the used/avail rings accordingly. [Fix 32-bit builds by changing 16lx format specifier to HWADDR_PRIx. --Stefan] Signed-off-by: Pierre Morel <pmorel@linux.vnet.ibm.com> Tested-by: Greg Kurz <gkurz@linux.vnet.ibm.com> Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com> Message-id: 1441625636-23773-1-git-send-email-pmorel@linux.vnet.ibm.com (changed __virtio16 into uint16_t, map descriptor table and available ring read-only) Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
495 lines
15 KiB
C
495 lines
15 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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*/
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static void *vring_map(MemoryRegion **mr, hwaddr phys, hwaddr 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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if (!section.mr || int128_get64(section.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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*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, 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, 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, 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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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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/* 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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/* TODO handle non-contiguous memory across region boundaries */
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iov->iov_base = vring_map(&mr, desc->addr, desc->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 = desc->len;
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*addr = desc->addr;
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*num += 1;
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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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/* 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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struct vring_desc *desc_ptr;
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MemoryRegion *mr;
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/* Translate indirect descriptor */
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desc_ptr = vring_map(&mr,
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indirect->addr + found * sizeof(desc),
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sizeof(desc), false);
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if (!desc_ptr) {
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error_report("Failed to map 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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copy_in_vring_desc(vdev, desc_ptr, &desc);
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memory_region_unref(mr);
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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)) {
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vring_avail_event(&vring->vr) =
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virtio_tswap16(vdev, vring->last_avail_idx);
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}
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return head;
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out:
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assert(ret < 0);
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if (ret == -EFAULT) {
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vring->broken = true;
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}
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vring_unmap_element(elem);
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return ret;
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}
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/* After we've used one of their buffers, we tell them about it.
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*
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* Stolen from linux/drivers/vhost/vhost.c.
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*/
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void vring_push(VirtIODevice *vdev, Vring *vring, VirtQueueElement *elem,
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int len)
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{
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unsigned int head = elem->index;
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uint16_t new;
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vring_unmap_element(elem);
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/* Don't touch vring if a fatal error occurred */
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if (vring->broken) {
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return;
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}
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/* The virtqueue contains a ring of used buffers. Get a pointer to the
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* next entry in that used ring. */
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vring_set_used_ring_id(vdev, vring, vring->last_used_idx % vring->vr.num,
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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;
|
|
}
|
|
}
|