Re: [PATCH v19 039/130] KVM: TDX: initialize VM with TDX specific parameters

Juergen Gross
2024-05-17T14:37:19Z

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On 17.05.24 16:32, Kirill A. Shutemov wrote:
> On Mon, Feb 26, 2024 at 12:25:41AM -0800, isaku.yamahata@intel.com wrote:
>> @@ -725,6 +967,17 @@ static int __init tdx_module_setup(void)
>>
>> tdx_info->nr_tdcs_pages = tdcs_base_size / PAGE_SIZE;
>>
>> + /*
>> + * Make TDH.VP.ENTER preserve RBP so that the stack unwinder
>> + * always work around it. Query the feature.
>> + */
>> + if (!(tdx_info->features0 & MD_FIELD_ID_FEATURES0_NO_RBP_MOD) &&
>> + !IS_ENABLED(CONFIG_FRAME_POINTER)) {
>
> I think it supposed to be IS_ENABLED(CONFIG_FRAME_POINTER). "!" shouldn't
> be here.

No, I don't think so.

With CONFIG_FRAME_POINTER %rbp is being saved and restored, so there is no
problem in case the seamcall is clobbering it.

Juergen

>
>> + pr_err("Too old version of TDX module. Consider upgrade.\n");
>> + ret = -EOPNOTSUPP;
>> + goto error_out;
>> + }
>> +
>> return 0;
>>
>

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