Re: [PATCH v3 09/21] x86/virt/tdx: Get information about TDX module and convertible memory

From: Dave Hansen
Date: Fri Apr 29 2022 - 13:49:51 EST

On 4/28/22 16:14, Kai Huang wrote:
> On Thu, 2022-04-28 at 07:06 -0700, Dave Hansen wrote:
>> On 4/27/22 17:15, Kai Huang wrote:
>>>> Couldn't we get rid of that comment if you did something like:
>>>> ret = tdx_get_sysinfo(&tdx_cmr_array, &tdx_sysinfo);
>>> Yes will do.
>>>> and preferably make the variables function-local.
>>> 'tdx_sysinfo' will be used by KVM too.
>> In other words, it's not a part of this series so I can't review whether
>> this statement is correct or whether there's a better way to hand this
>> information over to KVM.
>> This (minor) nugget influencing the design also isn't even commented or
>> addressed in the changelog.
> TDSYSINFO_STRUCT is 1024B and CMR array is 512B, so I don't think it should be
> in the stack. I can change to use dynamic allocation at the beginning and free
> it at the end of the function. KVM support patches can change it to static
> variable in the file.

2k of stack is big, but it isn't a deal breaker for something that's not
nested anywhere and that's only called once in a pretty controlled
setting and not in interrupt context. I wouldn't cry about it.