From: Dave Hansen <dave.hansen@intel.com>
To: "H. Peter Anvin" <hpa@zytor.com>,
Andrew Cooper <andrew.cooper3@citrix.com>,
Borislav Petkov <bp@alien8.de>
Cc: xin@zytor.com, linux-kernel@vger.kernel.org, tglx@linutronix.de,
mingo@redhat.com, dave.hansen@linux.intel.com, x86@kernel.org,
peterz@infradead.org, nik.borisov@suse.com,
houwenlong.hwl@antgroup.com
Subject: Re: [PATCH v1 2/4] x86/fred: Write to FRED MSRs with wrmsrns()
Date: Wed, 3 Jul 2024 09:43:05 -0700 [thread overview]
Message-ID: <dc1b2c50-6172-46a1-98a8-cec729afff38@intel.com> (raw)
In-Reply-To: <AD99CE51-62B3-494D-9107-7C9093126138@zytor.com>
On 7/3/24 09:06, H. Peter Anvin wrote:
> I believe tglx declared to use them unconditionally since FRED> depends on WRMSRNS (and the kernel enforces that.)
Ahh, I forgot about:
static const struct cpuid_dep cpuid_deps[] = {
...
{ X86_FEATURE_FRED, X86_FEATURE_WRMSRNS },
So, yeah, Xin's patch here is quite safe and when Boris said:
> Also, all those wrmsrns() writes better be behind a CPUID check.
... it *is* behind a CPUID check, but it's an implicit one.
next prev parent reply other threads:[~2024-07-03 16:43 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-03 8:54 [PATCH v1 0/4] Enable FRED earlier Xin Li (Intel)
2024-07-03 8:54 ` [PATCH v1 1/4] x86/fred: Parse cmdline param "fred=" in cpu_parse_early_param() Xin Li (Intel)
2024-07-04 11:20 ` Nikolay Borisov
2024-07-07 17:42 ` Xin Li
2024-07-03 8:54 ` [PATCH v1 2/4] x86/fred: Write to FRED MSRs with wrmsrns() Xin Li (Intel)
2024-07-03 15:43 ` Dave Hansen
2024-07-03 15:54 ` Borislav Petkov
2024-07-03 16:00 ` Andrew Cooper
2024-07-03 16:06 ` H. Peter Anvin
2024-07-03 16:17 ` Borislav Petkov
2024-07-05 2:45 ` H. Peter Anvin
2024-07-05 9:44 ` Borislav Petkov
2024-07-05 10:30 ` Andrew Cooper
2024-07-05 13:45 ` Borislav Petkov
2024-07-09 13:58 ` Xin Li
2024-07-09 20:51 ` H. Peter Anvin
2024-07-03 16:18 ` Andrew Cooper
2024-07-04 5:57 ` Xin Li
2024-07-04 7:58 ` H. Peter Anvin
2024-07-04 8:23 ` Borislav Petkov
2024-07-04 8:28 ` H. Peter Anvin
2024-07-03 16:43 ` Dave Hansen [this message]
2024-07-03 22:48 ` Xin Li
2024-07-05 9:28 ` Peter Zijlstra
2024-07-05 11:33 ` H. Peter Anvin
2024-07-03 8:54 ` [PATCH v1 3/4] x86/fred: Split FRED RSP initialization into a separate function Xin Li (Intel)
2024-07-03 8:54 ` [PATCH v1 4/4] x86/fred: Enable FRED right after init_mem_mapping() Xin Li (Intel)
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