On 7/29/2021 1:06 AM, Dave Hansen wrote:
On 7/28/21 7:52 AM, Tianyu Lan wrote:@@ -1986,7 +1988,9 @@ static int __set_memory_enc_dec(unsigned long addr, int numpages, bool enc) int ret;/* Nothing to do if memory encryption is not active */- if (!mem_encrypt_active()) + if (hv_is_isolation_supported()) + return hv_set_mem_enc(addr, numpages, enc); + else if (!mem_encrypt_active()) return 0;One more thing. If you're going to be patching generic code, please start using feature checks that can get optimized away at runtime. hv_is_isolation_supported() doesn't look like the world's cheapest check. It can't be inlined and costs at least a function call.
Yes, you are right. How about adding a static branch key for the check of isolation VM? This may reduce the check cost.
