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Subject: [OASIS Issue Tracker] (VIRTIO-35) race condition with multi-dword config accesses
[ https://tools.oasis-open.org/issues/browse/VIRTIO-35?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ] Michael Tsirkin updated VIRTIO-35: ---------------------------------- Fix Version/s: virtio 1.0 csprd01 > race condition with multi-dword config accesses > ----------------------------------------------- > > Key: VIRTIO-35 > URL: https://tools.oasis-open.org/issues/browse/VIRTIO-35 > Project: OASIS Virtual I/O Device (VIRTIO) TC > Issue Type: Bug > Reporter: Michael Tsirkin > Fix For: virtio 1.0 csprd01 > > > on many architectures, accesses larger than 32 bit can not be atomic. > Thus access to a device config field of >4 bytes is inherently racy > in case field can change. > For example, virtio-blk has > u64 capacity; > The following race can trigger: > driver reads low 32 bit > both low and high 32 bit change > driver reads high 32 bit > as a result, capacity observed is composed of > old low bits and new high bits which does not > make sense. > For legacy devices, spec allowed byte by byte access, > making the race even more common. -- This message was sent by Atlassian JIRA (v6.1.1#6155)
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