qemu-kvm/kvm-vhost-Track-descriptor-chain-in-private-at-SVQ.patch

124 lines
4.6 KiB
Diff

From 486647551223cc01f4dba87197030bbf4e674f0f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Eugenio=20P=C3=A9rez?= <eperezma@redhat.com>
Date: Thu, 21 Jul 2022 15:24:48 +0200
Subject: [PATCH 01/32] vhost: Track descriptor chain in private at SVQ
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
RH-Author: Eugenio Pérez <eperezma@redhat.com>
RH-MergeRequest: 108: Net Control Virtqueue shadow Support
RH-Commit: [1/27] 26d16dc383e3064ac6e4288d5c52b39fee0ad204 (eperezmartin/qemu-kvm)
RH-Bugzilla: 1939363
RH-Acked-by: Stefano Garzarella <sgarzare@redhat.com>
RH-Acked-by: Cindy Lu <lulu@redhat.com>
RH-Acked-by: Laurent Vivier <lvivier@redhat.com>
Bugzilla: https://bugzilla.redhat.com/1939363
Upstream Status: git://git.qemu.org/qemu.git
commit 495fe3a78749c39c0e772c4e1a55d6cb8a7e5292
Author: Eugenio Pérez <eperezma@redhat.com>
Date: Thu May 12 19:57:42 2022 +0200
vhost: Track descriptor chain in private at SVQ
The device could have access to modify them, and it definitely have
access when we implement packed vq. Harden SVQ maintaining a private
copy of the descriptor chain. Other fields like buffer addresses are
already maintained sepparatedly.
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Message-Id: <20220512175747.142058-2-eperezma@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
hw/virtio/vhost-shadow-virtqueue.c | 12 +++++++-----
hw/virtio/vhost-shadow-virtqueue.h | 6 ++++++
2 files changed, 13 insertions(+), 5 deletions(-)
diff --git a/hw/virtio/vhost-shadow-virtqueue.c b/hw/virtio/vhost-shadow-virtqueue.c
index b232803d1b..3155801f50 100644
--- a/hw/virtio/vhost-shadow-virtqueue.c
+++ b/hw/virtio/vhost-shadow-virtqueue.c
@@ -138,6 +138,7 @@ static void vhost_vring_write_descs(VhostShadowVirtqueue *svq, hwaddr *sg,
for (n = 0; n < num; n++) {
if (more_descs || (n + 1 < num)) {
descs[i].flags = flags | cpu_to_le16(VRING_DESC_F_NEXT);
+ descs[i].next = cpu_to_le16(svq->desc_next[i]);
} else {
descs[i].flags = flags;
}
@@ -145,10 +146,10 @@ static void vhost_vring_write_descs(VhostShadowVirtqueue *svq, hwaddr *sg,
descs[i].len = cpu_to_le32(iovec[n].iov_len);
last = i;
- i = cpu_to_le16(descs[i].next);
+ i = cpu_to_le16(svq->desc_next[i]);
}
- svq->free_head = le16_to_cpu(descs[last].next);
+ svq->free_head = le16_to_cpu(svq->desc_next[last]);
}
static bool vhost_svq_add_split(VhostShadowVirtqueue *svq,
@@ -336,7 +337,6 @@ static void vhost_svq_disable_notification(VhostShadowVirtqueue *svq)
static VirtQueueElement *vhost_svq_get_buf(VhostShadowVirtqueue *svq,
uint32_t *len)
{
- vring_desc_t *descs = svq->vring.desc;
const vring_used_t *used = svq->vring.used;
vring_used_elem_t used_elem;
uint16_t last_used;
@@ -365,7 +365,7 @@ static VirtQueueElement *vhost_svq_get_buf(VhostShadowVirtqueue *svq,
return NULL;
}
- descs[used_elem.id].next = svq->free_head;
+ svq->desc_next[used_elem.id] = svq->free_head;
svq->free_head = used_elem.id;
*len = used_elem.len;
@@ -540,8 +540,9 @@ void vhost_svq_start(VhostShadowVirtqueue *svq, VirtIODevice *vdev,
svq->vring.used = qemu_memalign(qemu_real_host_page_size, device_size);
memset(svq->vring.used, 0, device_size);
svq->ring_id_maps = g_new0(VirtQueueElement *, svq->vring.num);
+ svq->desc_next = g_new0(uint16_t, svq->vring.num);
for (unsigned i = 0; i < svq->vring.num - 1; i++) {
- svq->vring.desc[i].next = cpu_to_le16(i + 1);
+ svq->desc_next[i] = cpu_to_le16(i + 1);
}
}
@@ -574,6 +575,7 @@ void vhost_svq_stop(VhostShadowVirtqueue *svq)
virtqueue_detach_element(svq->vq, next_avail_elem, 0);
}
svq->vq = NULL;
+ g_free(svq->desc_next);
g_free(svq->ring_id_maps);
qemu_vfree(svq->vring.desc);
qemu_vfree(svq->vring.used);
diff --git a/hw/virtio/vhost-shadow-virtqueue.h b/hw/virtio/vhost-shadow-virtqueue.h
index e5e24c536d..c132c994e9 100644
--- a/hw/virtio/vhost-shadow-virtqueue.h
+++ b/hw/virtio/vhost-shadow-virtqueue.h
@@ -53,6 +53,12 @@ typedef struct VhostShadowVirtqueue {
/* Next VirtQueue element that guest made available */
VirtQueueElement *next_guest_avail_elem;
+ /*
+ * Backup next field for each descriptor so we can recover securely, not
+ * needing to trust the device access.
+ */
+ uint16_t *desc_next;
+
/* Next head to expose to the device */
uint16_t shadow_avail_idx;
--
2.31.1