Return-Path: Received: from [192.168.7.202] ([71.202.166.45]) (authenticated bits=0) by mail.zytor.com (8.18.1/8.17.1) with ESMTPSA id 56MIMkSj692590 (version=TLSv1.3 cipher=TLS_AES_128_GCM_SHA256 bits=128 verify=NO) for ; Tue, 22 Jul 2025 11:22:47 -0700 DKIM-Filter: OpenDKIM Filter v2.11.0 mail.zytor.com 56MIMkSj692590 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2025062101; t=1753208567; bh=dyteAFsAJy5+VmQ/vZVASq8c7iaJ+iMBDZ5Nx+HCzmY=; h=Date:Subject:To:References:From:In-Reply-To:From; b=nnoRrPuX9IJ+o1R7h9A6G2yU1Z6Z25CzI24+q6sTmlatPY95L9YrzXCzyvXlk0bNl ofB4oChO8SZeMR7Gda6mAq3onjvLSf4IdVNumFa34T1r3yhjlyQ14HjMUSeNMvsaBa 3sDt5+Lf48MxO1FEcDg/AO7SWl6qGbeCtBtJM2IQSMWIBb31ggqA0BdZcL9JYsNZwl 3mzCevgS0tXB8xztoUjOdP42LbaBGrcdyflSPklVaPH/kDQVx9qWFSKa0zGQVKeg0N 7ItKpH4We2plNju0g6uDwZBQBxyO38VQlCuQy+l/M/i6Hmn56rtFhzgymNsUAF54PV XPPXWUquDp/Gw== Message-ID: <9ffd7f0b-f196-41a1-83c2-4a830d1bb035@zytor.com> Date: Tue, 22 Jul 2025 11:22:46 -0700 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] x86: Clear LAM and FRED feature bits To: "H. Peter Anvin" References: <20250722074439.4069992-1-maciej.wieczor-retman@intel.com> <32382f60-79fb-4cfa-87b4-581f92c980da@zytor.com> <5654b3bc-15d4-443b-a7b1-2f9fd1d3e0aa@zytor.com> <91dd8b75-1191-4a3d-9f62-d94c325793fd@zytor.com> Content-Language: en-US From: Xin Li Autocrypt: addr=xin@zytor.com; keydata= xsDNBGUPz1cBDACS/9yOJGojBFPxFt0OfTWuMl0uSgpwk37uRrFPTTLw4BaxhlFL0bjs6q+0 2OfG34R+a0ZCuj5c9vggUMoOLdDyA7yPVAJU0OX6lqpg6z/kyQg3t4jvajG6aCgwSDx5Kzg5 Rj3AXl8k2wb0jdqRB4RvaOPFiHNGgXCs5Pkux/qr0laeFIpzMKMootGa4kfURgPhRzUaM1vy bsMsL8vpJtGUmitrSqe5dVNBH00whLtPFM7IbzKURPUOkRRiusFAsw0a1ztCgoFczq6VfAVu raTye0L/VXwZd+aGi401V2tLsAHxxckRi9p3mc0jExPc60joK+aZPy6amwSCy5kAJ/AboYtY VmKIGKx1yx8POy6m+1lZ8C0q9b8eJ8kWPAR78PgT37FQWKYS1uAroG2wLdK7FiIEpPhCD+zH wlslo2ETbdKjrLIPNehQCOWrT32k8vFNEMLP5G/mmjfNj5sEf3IOKgMTMVl9AFjsINLHcxEQ 6T8nGbX/n3msP6A36FDfdSEAEQEAAc0WWGluIExpIDx4aW5Aenl0b3IuY29tPsLBDQQTAQgA NxYhBIUq/WFSDTiOvUIqv2u9DlcdrjdRBQJlD89XBQkFo5qAAhsDBAsJCAcFFQgJCgsFFgID AQAACgkQa70OVx2uN1HUpgv/cM2fsFCQodLArMTX5nt9yqAWgA5t1srri6EgS8W3F+3Kitge tYTBKu6j5BXuXaX3vyfCm+zajDJN77JHuYnpcKKr13VcZi1Swv6Jx1u0II8DOmoDYLb1Q2ZW v83W55fOWJ2g72x/UjVJBQ0sVjAngazU3ckc0TeNQlkcpSVGa/qBIHLfZraWtdrNAQT4A1fa sWGuJrChBFhtKbYXbUCu9AoYmmbQnsx2EWoJy3h7OjtfFapJbPZql+no5AJ3Mk9eE5oWyLH+ QWqtOeJM7kKvn/dBudokFSNhDUw06e7EoVPSJyUIMbYtUO7g2+Atu44G/EPP0yV0J4lRO6EA wYRXff7+I1jIWEHpj5EFVYO6SmBg7zF2illHEW31JAPtdDLDHYcZDfS41caEKOQIPsdzQkaQ oW2hchcjcMPAfyhhRzUpVHLPxLCetP8vrVhTvnaZUo0xaVYb3+wjP+D5j/3+hwblu2agPsaE vgVbZ8Fx3TUxUPCAdr/p73DGg57oHjgezsDNBGUPz1gBDAD4Mg7hMFRQqlzotcNSxatlAQNL MadLfUTFz8wUUa21LPLrHBkUwm8RujehJrzcVbPYwPXIO0uyL/F///CogMNx7Iwo6by43KOy g89wVFhyy237EY76j1lVfLzcMYmjBoTH95fJC/lVb5Whxil6KjSN/R/y3jfG1dPXfwAuZ/4N cMoOslWkfZKJeEut5aZTRepKKF54T5r49H9F7OFLyxrC/uI9UDttWqMxcWyCkHh0v1Di8176 jjYRNTrGEfYfGxSp+3jYL3PoNceIMkqM9haXjjGl0W1B4BidK1LVYBNov0rTEzyr0a1riUrp Qk+6z/LHxCM9lFFXnqH7KWeToTOPQebD2B/Ah5CZlft41i8L6LOF/LCuDBuYlu/fI2nuCc8d m4wwtkou1Y/kIwbEsE/6RQwRXUZhzO6llfoN96Fczr/RwvPIK5SVMixqWq4QGFAyK0m/1ap4 bhIRrdCLVQcgU4glo17vqfEaRcTW5SgX+pGs4KIPPBE5J/ABD6pBnUUAEQEAAcLA/AQYAQgA JhYhBIUq/WFSDTiOvUIqv2u9DlcdrjdRBQJlD89ZBQkFo5qAAhsMAAoJEGu9DlcdrjdR4C0L /RcjolEjoZW8VsyxWtXazQPnaRvzZ4vhmGOsCPr2BPtMlSwDzTlri8BBG1/3t/DNK4JLuwEj OAIE3fkkm+UG4Kjud6aNeraDI52DRVCSx6xff3bjmJsJJMb12mWglN6LjdF6K+PE+OTJUh2F dOhslN5C2kgl0dvUuevwMgQF3IljLmi/6APKYJHjkJpu1E6luZec/lRbetHuNFtbh3xgFIJx 2RpgVDP4xB3f8r0I+y6ua+p7fgOjDLyoFjubRGed0Be45JJQEn7A3CSb6Xu7NYobnxfkwAGZ Q81a2XtvNS7Aj6NWVoOQB5KbM4yosO5+Me1V1SkX2jlnn26JPEvbV3KRFcwV5RnDxm4OQTSk PYbAkjBbm+tuJ/Sm+5Yp5T/BnKz21FoCS8uvTiziHj2H7Cuekn6F8EYhegONm+RVg3vikOpn gao85i4HwQTK9/D1wgJIQkdwWXVMZ6q/OALaBp82vQ2U9sjTyFXgDjglgh00VRAHP7u1Rcu4 l75w1xInsg== In-Reply-To: <91dd8b75-1191-4a3d-9f62-d94c325793fd@zytor.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 7/22/2025 11:13 AM, H. Peter Anvin wrote: > On 2025-07-22 11:08, H. Peter Anvin wrote: >>> >>> Yes, something like: >>> >>> void __init init_cpu_cap(void) >>> { >>> for (i = 0; i < NCAPINTS; i++) { >>> cpu_caps_set[i] = REQUIRED_MASK(i); >>> cpu_caps_cleared[i] = DISABLED_MASK(i); >>> } >>> } >>> >>> And it would be better if it could be done at build time (to avoid >>> changing Xen which has a dedicated startup code path): >>> >>> __u32 cpu_caps_{set,cleared}[NCAPINTS + NBUGINTS] = { >>> {REQUIRED,DISABLED}_MASK(i), >>> }; >>> >>> And then apply_forced_caps() will do the rest automatically :) >> >> Yeah: >> >> u32 __init cpu_caps_cleared = { ... }; >> >> ... which can come straight out of the awk script. >> > > Heck, I think I even did something like this in the first version, but > tglx or someone else asked to axe it because it wasn't being used (yet.) ;) > diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 5809534ecc98..eb075fbf337e 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -703,8 +703,8 @@ static const char *table_lookup_model(struct cpuinfo_x86 *c) } /* Aligned to unsigned long to avoid split lock in atomic bitmap ops */ -__u32 cpu_caps_cleared[NCAPINTS + NBUGINTS] __aligned(sizeof(unsigned long)); -__u32 cpu_caps_set[NCAPINTS + NBUGINTS] __aligned(sizeof(unsigned long)); +__u32 cpu_caps_cleared[NCAPINTS + NBUGINTS] __aligned(sizeof(unsigned long)) = DISABLED_MASK_INIT_VALUES; +__u32 cpu_caps_set[NCAPINTS + NBUGINTS] __aligned(sizeof(unsigned long)) = REQUIRED_MASK_INIT_VALUES; #ifdef CONFIG_X86_32 /* The 32-bit entry code needs to find cpu_entry_area. */ diff --git a/arch/x86/tools/cpufeaturemasks.awk b/arch/x86/tools/cpufeaturemasks.awk index 173d5bf2d999..6b3583304ee8 100755 --- a/arch/x86/tools/cpufeaturemasks.awk +++ b/arch/x86/tools/cpufeaturemasks.awk @@ -81,7 +81,13 @@ END { printf "\t\\\n\t\t((x) >> 5) == %2d ? %s_MASK%d :", i, s, i; } printf " 0\t\\\n"; - printf "\t) & (1U << ((x) & 31)))\n\n"; + printf "\t) & (1U << ((x) & 31)))\n"; + + printf "\n#define %s_MASK_INIT_VALUES\t\t\t\\", s; + printf "\n\t{\t\t\t\t\t\t\\"; + for (i = 0; i < ncapints; i++) + printf "\n\t\t%s_MASK%d,\t\t\t\\", s, i; + printf "\n\t}\n\n"; } printf "#endif /* _ASM_X86_CPUFEATUREMASKS_H */\n";