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authorJohn Snow <jsnow@redhat.com>2018-06-08 13:17:36 -0400
committerJohn Snow <jsnow@redhat.com>2018-06-08 13:17:36 -0400
commit5694c7eacce6b263ad7497cc1bb76aad746cfd4e (patch)
treeec97986800d1013607960eceaf189d1d320bb298 /hw/9pfs
parentdc5a43eda68fff32c7b0b43847332db325b094f3 (diff)
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ahci: fix PxCI register race
Fixes: https://bugs.launchpad.net/qemu/+bug/1769189 AHCI presently signals completion prior to the PxCI register being cleared to indicate completion. If a guest driver attempts to issue a new command in its IRQ handler, it might be surprised to learn there is still a command pending. In the case of Windows 10's boot driver, it will actually poll the IRQ register hoping to find out when the command is done running -- which will never happen, as there isn't a command running. Fix this: clear PxCI in ahci_cmd_done and not in the asynchronous BH. Because it now runs synchronously, we don't need to check if the command is actually done by spying on the ATA registers. We know it's done. CC: qemu-stable <qemu-stable@nongnu.org> Reported-by: François Guerraz <kubrick@fgv6.net> Tested-by: Bruce Rogers <brogers@suse.com> Signed-off-by: John Snow <jsnow@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Jeff Cody <jcody@redhat.com> Message-id: 20180531004323.4611-3-jsnow@redhat.com Signed-off-by: John Snow <jsnow@redhat.com>
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