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From: Markus Armbruster <armbru@redhat.com>
References: <1471444747-6277-1-git-send-email-caoj.fnst@cn.fujitsu.com>
	<1471444747-6277-2-git-send-email-caoj.fnst@cn.fujitsu.com>
Date: Thu, 18 Aug 2016 09:14:27 +0200
In-Reply-To: <1471444747-6277-2-git-send-email-caoj.fnst@cn.fujitsu.com> (Cao
	jin's message of "Wed, 17 Aug 2016 22:39:02 +0800")
Message-ID: <87h9aift0s.fsf@dusky.pond.sub.org>
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Subject: Re: [Qemu-devel] [PATCH 1/6] msix_init: assert programming error
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To: Cao jin <caoj.fnst@cn.fujitsu.com>
Cc: qemu-devel@nongnu.org, Marcel Apfelbaum <marcel@redhat.com>, "Michael S. Tsirkin" <mst@redhat.com>

Cao jin <caoj.fnst@cn.fujitsu.com> writes:

> CC: Markus Armbruster <armbru@redhat.com>
> CC: Marcel Apfelbaum <marcel@redhat.com>
> CC: Michael S. Tsirkin <mst@redhat.com>
> Signed-off-by: Cao jin <caoj.fnst@cn.fujitsu.com>
> ---
>  hw/pci/msix.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/hw/pci/msix.c b/hw/pci/msix.c
> index 0ec1cb1..384a29d 100644
> --- a/hw/pci/msix.c
> +++ b/hw/pci/msix.c
> @@ -253,9 +253,7 @@ int msix_init(struct PCIDevice *dev, unsigned short nentries,
>          return -ENOTSUP;
>      }
>  
> -    if (nentries < 1 || nentries > PCI_MSIX_FLAGS_QSIZE + 1) {
> -        return -EINVAL;
> -    }
> +    assert(nentries >= 1 && nentries <= PCI_MSIX_FLAGS_QSIZE + 1);
>  
>      table_size = nentries * PCI_MSIX_ENTRY_SIZE;
>      pba_size = QEMU_ALIGN_UP(nentries, 64) / 8;
> @@ -266,7 +264,7 @@ int msix_init(struct PCIDevice *dev, unsigned short nentries,
>          table_offset + table_size > memory_region_size(table_bar) ||
>          pba_offset + pba_size > memory_region_size(pba_bar) ||
>          (table_offset | pba_offset) & PCI_MSIX_FLAGS_BIRMASK) {
> -        return -EINVAL;
> +        assert(0);
>      }
>  
>      cap = pci_add_capability(dev, PCI_CAP_ID_MSIX, cap_pos, MSIX_CAP_LENGTH);

Please explain in the commit message why these are programming errors.
If you're unsure how, give it a try in a reply to this message, and
we'll hammer out something together.