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authorGuilherme G. Piccoli2020-03-20 09:55:34 -0300
committerDavid S. Miller2020-03-25 12:03:29 -0700
commit428c491332bca498c8eb2127669af51506c346c7 (patch)
tree743a79068e78fd61d3c319adc510fe49f2f2b07a /drivers/net/wireguard/queueing.h
parentc085dbfb1cfcf74e2ef2ef435291e7e63f046d6a (diff)
net: ena: Add PCI shutdown handler to allow safe kexec
Currently ENA only provides the PCI remove() handler, used during rmmod for example. This is not called on shutdown/kexec path; we are potentially creating a failure scenario on kexec: (a) Kexec is triggered, no shutdown() / remove() handler is called for ENA; instead pci_device_shutdown() clears the master bit of the PCI device, stopping all DMA transactions; (b) Kexec reboot happens and the device gets enabled again, likely having its FW with that DMA transaction buffered; then it may trigger the (now invalid) memory operation in the new kernel, corrupting kernel memory area. This patch aims to prevent this, by implementing a shutdown() handler quite similar to the remove() one - the difference being the handling of the netdev, which is unregistered on remove(), but following the convention observed in other drivers, it's only detached on shutdown(). This prevents an odd issue in AWS Nitro instances, in which after the 2nd kexec the next one will fail with an initrd corruption, caused by a wild DMA write to invalid kernel memory. The lspci output for the adapter present in my instance is: 00:05.0 Ethernet controller [0200]: Amazon.com, Inc. Elastic Network Adapter (ENA) [1d0f:ec20] Suggested-by: Gavin Shan <gshan@redhat.com> Signed-off-by: Guilherme G. Piccoli <gpiccoli@canonical.com> Acked-by: Sameeh Jubran <sameehj@amazon.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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