From: Peter Zijlstra <peterz@infradead.org>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Borislav Petkov <bp@alien8.de>,
dave.hansen@intel.com, xin@zytor.com,
linux-kernel@vger.kernel.org, hpa@zytor.com, tglx@linutronix.de,
mingo@redhat.com, dave.hansen@linux.intel.com, x86@kernel.org,
nik.borisov@suse.com, houwenlong.hwl@antgroup.com
Subject: Re: [PATCH v1 2/4] x86/fred: Write to FRED MSRs with wrmsrns()
Date: Fri, 5 Jul 2024 11:28:05 +0200 [thread overview]
Message-ID: <20240705092805.GC11386@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <15f56e6a-6edd-43d0-8e83-bb6430096514@citrix.com>
On Wed, Jul 03, 2024 at 05:00:53PM +0100, Andrew Cooper wrote:
> /* Non-serialising WRMSR, when available. Falls back to a serialising WRMSR. */
> static inline void wrmsrns(uint32_t msr, uint32_t lo, uint32_t hi)
> {
> /*
> * WRMSR is 2 bytes. WRMSRNS is 3 bytes. Pad WRMSR with a redundant CS
> * prefix to avoid a trailing NOP.
> */
> alternative_input(".byte 0x2e; wrmsr",
> ".byte 0x0f,0x01,0xc6", X86_FEATURE_WRMSRNS,
> "c" (msr), "a" (lo), "d" (hi));
> }
FWIW, I favour this variant.
next prev parent reply other threads:[~2024-07-05 9:28 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
2024-07-03 22:48 ` Xin Li
2024-07-05 9:28 ` Peter Zijlstra [this message]
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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