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Re: [PATCH v3 02/22] include/xen/slr-table.h: Secure Launch Resource Table definitions
- To: Sergii Dmytruk <sergii.dmytruk@xxxxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Mon, 14 Jul 2025 09:33:09 +0200
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- Cc: "Daniel P. Smith" <dpsmith@xxxxxxxxxxxxxxxxxxxx>, Ross Philipson <ross.philipson@xxxxxxxxxx>, trenchboot-devel@xxxxxxxxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxxx
- Delivery-date: Mon, 14 Jul 2025 07:33:23 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 13.07.2025 19:29, Sergii Dmytruk wrote:
> On Tue, Jul 08, 2025 at 08:52:36AM +0200, Jan Beulich wrote:
>> On 07.07.2025 19:31, Sergii Dmytruk wrote:
>>> On Mon, Jul 07, 2025 at 10:29:46AM +0200, Jan Beulich wrote:
>>>>>> ... then isn't used right here, instead requiring a cast somewhere
>>>>>> (presumably,
>>>>>> as code using this isn't visible in this patch).
>>>>>
>>>>> As was mentioned earlier: because size of a pointer between Xen and a
>>>>> bootloader doesn't necessarily match. What you're proposing can break
>>>>> under certain conditions.
>>>>
>>>> But the header isn't shared with a bootloader's code base. It's private to
>>>> Xen.
>>>
>>> Yes, but sources of Xen be compiled with different size of a pointer
>>> which messes up the interpretation of the data. I tried using
>>> BUILD_BUG_ON() to enforce the pointer is 64-bit and early code stopped
>>> compiling. The structures must not vary like that.
>>
>> Hmm. Does early code actually need to have this struct exposed to it?
>
> It doesn't use this particular structure, but it uses some other ones in
> the header (also SLRT entries, but of different types). Making a
> separate header just to get rid of a cast doesn't seem to be worth it.
Which I also didn't suggest. Didn't I see an EARLY_<something> #define-d
somewhere? Couldn't you key exposure of the structure to that not being
defined?
Jan
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