Re: [PATCH v3 3/3] vhost: Don't call log_access_ok() when using IOTLB
From: Jason Wang <hidden>
Date: 2020-10-10 03:09:54
Also in:
kvm, lkml, netdev, qemu-devel
On 2020/10/3 下午6:02, Greg Kurz wrote:
When the IOTLB device is enabled, the log_guest_addr that is passed by userspace to the VHOST_SET_VRING_ADDR ioctl, and which is then written to vq->log_addr, is a GIOVA. All writes to this address are translated by log_user() to writes to an HVA, and then ultimately logged through the corresponding GPAs in log_write_hva(). No logging will ever occur with vq->log_addr in this case. It is thus wrong to pass vq->log_addr and log_guest_addr to log_access_vq() which assumes they are actual GPAs. Introduce a new vq_log_used_access_ok() helper that only checks accesses to the log for the used structure when there isn't an IOTLB device around. Signed-off-by: Greg Kurz <redacted>
Acked-by: Jason Wang <redacted> In the future, we may consider to deprecate log_guest_addr since in any case regardless of IOTLB ennoblement we can get GPA from either IOTLB or MEM table. Thanks
quoted hunk
--- drivers/vhost/vhost.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-)diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 9d2c225fb518..9ad45e1d27f0 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c@@ -1370,6 +1370,20 @@ bool vhost_log_access_ok(struct vhost_dev *dev) } EXPORT_SYMBOL_GPL(vhost_log_access_ok); +static bool vq_log_used_access_ok(struct vhost_virtqueue *vq, + void __user *log_base, + bool log_used, + u64 log_addr) +{ + /* If an IOTLB device is present, log_addr is a GIOVA that + * will never be logged by log_used(). */ + if (vq->iotlb) + return true; + + return !log_used || log_access_ok(log_base, log_addr, + vhost_get_used_size(vq, vq->num)); +} + /* Verify access for write logging. */ /* Caller should have vq mutex and device mutex */ static bool vq_log_access_ok(struct vhost_virtqueue *vq,@@ -1377,8 +1391,7 @@ static bool vq_log_access_ok(struct vhost_virtqueue *vq, { return vq_memory_access_ok(log_base, vq->umem, vhost_has_feature(vq, VHOST_F_LOG_ALL)) && - (!vq->log_used || log_access_ok(log_base, vq->log_addr, - vhost_get_used_size(vq, vq->num))); + vq_log_used_access_ok(vq, log_base, vq->log_used, vq->log_addr); } /* Can we start vq? */@@ -1517,9 +1530,9 @@ static long vhost_vring_set_addr(struct vhost_dev *d, return -EINVAL; /* Also validate log access for used ring if enabled. */ - if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) && - !log_access_ok(vq->log_base, a.log_guest_addr, - vhost_get_used_size(vq, vq->num))) + if (!vq_log_used_access_ok(vq, vq->log_base, + a.flags & (0x1 << VHOST_VRING_F_LOG), + a.log_guest_addr)) return -EINVAL; }
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