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Re: [PATCH v5 3/7] x86/hvm: Allow access to registers on the same page as MSI-X table
- To: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Mon, 29 Apr 2024 08:37:56 +0200
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- Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
- Delivery-date: Mon, 29 Apr 2024 06:37:58 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 26.04.2024 17:26, Marek Marczykowski-Górecki wrote:
> On Thu, Apr 25, 2024 at 01:15:34PM +0200, Jan Beulich wrote:
>> On 13.03.2024 16:16, Marek Marczykowski-Górecki wrote:
>>> + hwaddr = fix_to_virt(fixmap_idx) + PAGE_OFFSET(address);
>>> +
>>> + switch ( len )
>>> + {
>>> + case 1:
>>> + *pval = readb(hwaddr);
>>> + break;
>>> +
>>> + case 2:
>>> + *pval = readw(hwaddr);
>>> + break;
>>> +
>>> + case 4:
>>> + *pval = readl(hwaddr);
>>> + break;
>>> +
>>> + case 8:
>>> + *pval = readq(hwaddr);
>>> + break;
>>> +
>>> + default:
>>> + ASSERT_UNREACHABLE();
>>
>> Misra demands "break;" to be here for release builds. In fact I wonder
>> why "*pval = ~0UL;" isn't put here, too. Question of course is whether
>> in such a case a true error indicator wouldn't be yet better.
>
> I don't think it possible for the msixtbl_read() (that calls
> adjacent_read()) to be called with other sizes.
I agree, but scanners won't know.
Jan
> The default label is here exactly to make it obvious for the reader.
>
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