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453eac3124
It is possible that a guest might issue a CCW with a length of zero,
and will expect a particular response. Consider this chain:
Address Format-1 CCW
-------- -----------------
0 33110EC0 346022CC 33177468
1 33110EC8 CF200000 3318300C
CCW[0] moves a little more than two pages, but also has the
Suppress Length Indication (SLI) bit set to handle the expectation
that considerably less data will be moved. CCW[1] also has the SLI
bit set, and has a length of zero. Once vfio-ccw does its magic,
the kernel issues a start subchannel on behalf of the guest with this:
Address Format-1 CCW
-------- -----------------
0 021EDED0 346422CC 021F0000
1 021EDED8 CF240000 3318300C
Both CCWs were converted to an IDAL and have the corresponding flags
set (which is by design), but only the address of the first data
address is converted to something the host is aware of. The second
CCW still has the address used by the guest, which happens to be (A)
(probably) an invalid address for the host, and (B) an invalid IDAW
address (doubleword boundary, etc.).
While the I/O fails, it doesn't fail correctly. In this example, we
would receive a program check for an invalid IDAW address, instead of
a unit check for an invalid command.
To fix this, revert commit
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| char | ||
| cio | ||
| crypto | ||
| net | ||
| scsi | ||
| virtio | ||
| Makefile | ||