On 12/13/2022 3:41 AM, Michael Kelley (LINUX) wrote:
@@ -228,6 +234,12 @@ static int hv_cpu_die(unsigned int cpu) if (hv_vp_assist_page && hv_vp_assist_page[cpu]) { union hv_vp_assist_msr_contents msr = { 0 }; + + if (hv_isolation_type_en_snp()) + WARN_ON_ONCE(set_memory_encrypted( + (unsigned long)hv_vp_assist_page[cpu], + 1) != 0); +The re-encryption should not be done here (or anywhere else, for that matter) since the VP assist pages are never freed. The Hyper-V synthetic MSR pointing to the page gets cleared, but the memory isn't freed. If the CPU should come back online later, the previously allocated VP assist page is reused. The decryption in hv_cpu_init() is done only when a new page is allocated to use as a VP assist page. So just leave the page decrypted here, and it will get reused in its decrypted state. This handling of the VP assist page is admittedly a bit weird. But it is needed. See discussion with Vitaly Kuznetsov here: https://lore.kernel.org/linux-hyperv/878rkqr7ku.fsf@xxxxxxxxxxxxxxxxxxxxxxxxxxx/
Agree. Good point. Will update in the next version. Thanks.
