105 lines
4.0 KiB
Diff
105 lines
4.0 KiB
Diff
From de3c31598e00c4bcee42f3921f714b0928716535 Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Eugenio=20P=C3=A9rez?= <eperezma@redhat.com>
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Date: Thu, 12 May 2022 19:57:42 +0200
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Subject: [PATCH] vhost: Track descriptor chain in private at SVQ
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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The device could have access to modify them, and it definitely have
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access when we implement packed vq. Harden SVQ maintaining a private
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copy of the descriptor chain. Other fields like buffer addresses are
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already maintained sepparatedly.
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Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
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Message-Id: <20220512175747.142058-2-eperezma@redhat.com>
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Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
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Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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Signed-off-by: fangyi <eric.fangyi@huawei.com>
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---
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hw/virtio/vhost-shadow-virtqueue.c | 12 +++++++-----
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hw/virtio/vhost-shadow-virtqueue.h | 6 ++++++
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2 files changed, 13 insertions(+), 5 deletions(-)
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diff --git a/hw/virtio/vhost-shadow-virtqueue.c b/hw/virtio/vhost-shadow-virtqueue.c
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index c38b6b6ab5..6057a437df 100644
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--- a/hw/virtio/vhost-shadow-virtqueue.c
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+++ b/hw/virtio/vhost-shadow-virtqueue.c
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@@ -137,6 +137,7 @@ static void vhost_vring_write_descs(VhostShadowVirtqueue *svq, hwaddr *sg,
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for (n = 0; n < num; n++) {
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if (more_descs || (n + 1 < num)) {
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descs[i].flags = flags | cpu_to_le16(VRING_DESC_F_NEXT);
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+ descs[i].next = cpu_to_le16(svq->desc_next[i]);
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} else {
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descs[i].flags = flags;
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}
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@@ -144,10 +145,10 @@ static void vhost_vring_write_descs(VhostShadowVirtqueue *svq, hwaddr *sg,
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descs[i].len = cpu_to_le32(iovec[n].iov_len);
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last = i;
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- i = cpu_to_le16(descs[i].next);
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+ i = cpu_to_le16(svq->desc_next[i]);
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}
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- svq->free_head = le16_to_cpu(descs[last].next);
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+ svq->free_head = le16_to_cpu(svq->desc_next[last]);
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}
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static bool vhost_svq_add_split(VhostShadowVirtqueue *svq,
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@@ -335,7 +336,6 @@ static void vhost_svq_disable_notification(VhostShadowVirtqueue *svq)
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static VirtQueueElement *vhost_svq_get_buf(VhostShadowVirtqueue *svq,
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uint32_t *len)
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{
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- vring_desc_t *descs = svq->vring.desc;
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const vring_used_t *used = svq->vring.used;
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vring_used_elem_t used_elem;
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uint16_t last_used;
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@@ -364,7 +364,7 @@ static VirtQueueElement *vhost_svq_get_buf(VhostShadowVirtqueue *svq,
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return NULL;
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}
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- descs[used_elem.id].next = svq->free_head;
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+ svq->desc_next[used_elem.id] = svq->free_head;
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svq->free_head = used_elem.id;
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*len = used_elem.len;
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@@ -539,8 +539,9 @@ void vhost_svq_start(VhostShadowVirtqueue *svq, VirtIODevice *vdev,
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svq->vring.used = qemu_memalign(qemu_real_host_page_size, device_size);
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memset(svq->vring.used, 0, device_size);
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svq->ring_id_maps = g_new0(VirtQueueElement *, svq->vring.num);
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+ svq->desc_next = g_new0(uint16_t, svq->vring.num);
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for (unsigned i = 0; i < svq->vring.num - 1; i++) {
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- svq->vring.desc[i].next = cpu_to_le16(i + 1);
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+ svq->desc_next[i] = cpu_to_le16(i + 1);
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}
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}
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@@ -573,6 +574,7 @@ void vhost_svq_stop(VhostShadowVirtqueue *svq)
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virtqueue_detach_element(svq->vq, next_avail_elem, 0);
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}
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svq->vq = NULL;
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+ g_free(svq->desc_next);
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g_free(svq->ring_id_maps);
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qemu_vfree(svq->vring.desc);
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qemu_vfree(svq->vring.used);
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diff --git a/hw/virtio/vhost-shadow-virtqueue.h b/hw/virtio/vhost-shadow-virtqueue.h
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index e5e24c536d..c132c994e9 100644
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--- a/hw/virtio/vhost-shadow-virtqueue.h
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+++ b/hw/virtio/vhost-shadow-virtqueue.h
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@@ -53,6 +53,12 @@ typedef struct VhostShadowVirtqueue {
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/* Next VirtQueue element that guest made available */
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VirtQueueElement *next_guest_avail_elem;
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+ /*
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+ * Backup next field for each descriptor so we can recover securely, not
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+ * needing to trust the device access.
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+ */
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+ uint16_t *desc_next;
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+
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/* Next head to expose to the device */
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uint16_t shadow_avail_idx;
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--
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2.27.0
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