[TODO TDX] Check VP assist page for TDX guest

[ramesh-thomas]

drivers/hv/hv_common.c: hv_common_init()

  /*
 * The VP assist page is useless to a TDX guest: the only use we
 * would have for it is lazy EOI, which can not be used with TDX.
 *
 * TODO TDX: UH doens't require this on TDX right now, but we may
 * want it in the future?

(Migrated internal issue #1262)

[ramesh-thomas]

yjiang5 opened on Sep 24:

This TODO is not so useful and can possibly be removed.

[ramesh-thomas]

@yamahata confirms it is not needed for TDX.

[ramesh-thomas]

@chris-oo since TDX does not need it, do we need any change to the below code? Looks like we only need the else part and initialize hv_vp_assist_page = NULL;

    /*
     * The VP assist page is useless to a TDX guest: the only use we
     * would have for it is lazy EOI, which can not be used with TDX.
     *
     * TODO TDX: UH doens't require this on TDX right now, but we may
     * want it in the future?
     */
    if (hv_isolation_type_tdx())
            hv_vp_assist_page = NULL;
    else {
            hv_vp_assist_page = kcalloc(num_possible_cpus(),
                                            sizeof(*hv_vp_assist_page), GFP_KERNEL);
            if (!hv_vp_assist_page) {
                    hv_common_free();
                    ret = -ENOMEM;
            }
    }

[yamahata]

The logic (if tdx hv_vp_assist_page = NULL) looks reasonable.