Messages in this thread | | | Subject | Re: [PATCH 03/13] x86/HV: Add new hvcall guest address host visibility support | From | Tianyu Lan <> | Date | Thu, 29 Jul 2021 21:01:49 +0800 |
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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.
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