Re: [Qemu-devel] [PATCH 1/1] ide/atapi: Mark non-data commands as complete

[Paolo Bonzini <pbonzini@redhat.com>]

Il 12/09/2014 18:00, John Snow ha scritto:
> When the command completion code in IDE and AHCI
> was unified to put all command completion inside
> of a callback, "cmd_done," we neglected to
> ensure that all AHCI/ATAPI command paths would
> eventually register as finished. for the PCI
> interface to IDE this is not a problem because
> cmd_done is a nop, but the AHCI implementation
> needs to send a D2H_REG_FIS and interrupt back
> to the guest to inform of completion.
> 
> This patch adds calls to ide_set_inactive,
> which calls ide_cmd_done, inside of
> ide_atapi_cmd_ok and ide_atapi_cmd_error.
> 
> This fixes regressions observed by trying to boot QEMU
> with a Fedora 20 live CD under Q35/AHCI, which uses
> ATAPI command 0x00, which is a status check that may
> cause a hang because we never complete, and ATAPI
> command 0x56, which is unsupported by our current
> implementation and results in an error that we never
> report back to the guest.
> 
> Signed-off-by: John Snow <jsnow@redhat.com>
> ---
>  hw/ide/atapi.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/hw/ide/atapi.c b/hw/ide/atapi.c
> index 3d92b52..3e9ad7b 100644
> --- a/hw/ide/atapi.c
> +++ b/hw/ide/atapi.c
> @@ -134,6 +134,7 @@ void ide_atapi_cmd_ok(IDEState *s)
>      s->error = 0;
>      s->status = READY_STAT | SEEK_STAT;
>      s->nsector = (s->nsector & ~7) | ATAPI_INT_REASON_IO | ATAPI_INT_REASON_CD;
> +    ide_set_inactive(s, false);
>      ide_set_irq(s->bus);
>  }
>  
> @@ -147,6 +148,7 @@ void ide_atapi_cmd_error(IDEState *s, int sense_key, int asc)
>      s->nsector = (s->nsector & ~7) | ATAPI_INT_REASON_IO | ATAPI_INT_REASON_CD;
>      s->sense_key = sense_key;
>      s->asc = asc;
> +    ide_set_inactive(s, false);
>      ide_set_irq(s->bus);
>  }
>  
> 

The set_inactive callback does nothing on AHCI, but is DMA-specific for
PCI.  Even though you probably aren't seeing any bad effects, I think
ide_transfer_stop is a better match.  It would also match what
ide_atapi_cmd_reply_end does before calling ide_atapi_cmd_error (via
ide_atapi_io_error) and before an inlined copy of ide_atapi_cmd_ok.  So
you would get a bugfix and a cleanup at once.

Paolo