From: Dave Hansen <dave.hansen@intel.com>
To: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Pavel Machek <pavel@ucw.cz>,
Andrew Cooper <Andrew.Cooper3@citrix.com>,
degoede@redhat.com
Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
Daniel Sneddon <daniel.sneddon@linux.intel.com>,
antonio.gomez.iglesias@linux.intel.com
Subject: Re: [PATCH 1/3] x86/tsx: Add feature bit for TSX control MSR support
Date: Tue, 8 Nov 2022 10:27:56 -0800 [thread overview]
Message-ID: <9eb8f395-c77f-a0bf-96b7-f1a3bb178c48@intel.com> (raw)
In-Reply-To: <8592af5e3b95b197231445beb8c3123948ced15a.1663025154.git.pawan.kumar.gupta@linux.intel.com>
On 9/12/22 16:39, Pawan Gupta wrote:
> Support for TSX control MSR is enumerated in MSR_IA32_ARCH_CAPABILITIES.
> This is different from how other CPU features are enumerated i.e. via
> CPUID. Enumerating support for TSX control currently has an overhead of
> reading the MSR every time which can be avoided.
I only see tsx_ctrl_is_supported() getting called in three places:
> 1 tsx.c tsx_clear_cpuid 138 } else if (tsx_ctrl_is_supported()) {
> 2 tsx.c tsx_dev_mode_disable 161 if (!boot_cpu_has_bug(X86_BUG_TAA) || !tsx_ctrl_is_supported() ||
> 3 tsx.c tsx_init 194 if (!tsx_ctrl_is_supported()) {
Those all look like boot-time things to me. Why does the overhead matter?
next prev parent reply other threads:[~2022-11-08 18:29 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-12 23:38 [PATCH 0/3] Check enumeration before MSR save/restore Pawan Gupta
2022-09-12 23:39 ` [PATCH 1/3] x86/tsx: Add feature bit for TSX control MSR support Pawan Gupta
2022-11-08 18:27 ` Dave Hansen [this message]
2022-11-08 22:06 ` Pawan Gupta
2022-09-12 23:40 ` [PATCH 2/3] x86/cpu/amd: Add feature bit for MSR_AMD64_LS_CFG enumeration Pawan Gupta
2022-11-08 18:54 ` Borislav Petkov
2022-11-08 22:51 ` Pawan Gupta
2022-11-08 23:10 ` Borislav Petkov
2022-11-09 0:45 ` Andrew Cooper
2022-11-09 17:37 ` Pawan Gupta
2022-11-09 18:34 ` Borislav Petkov
2022-11-09 21:41 ` Pawan Gupta
2022-11-10 0:00 ` Andrew Cooper
2022-11-10 6:09 ` Pawan Gupta
2022-11-09 2:18 ` Pawan Gupta
2022-09-12 23:41 ` [PATCH 3/3] x86/pm: Add enumeration check before spec MSRs save/restore setup Pawan Gupta
2022-11-08 18:40 ` Dave Hansen
2022-11-08 22:09 ` Pawan Gupta
2022-09-13 0:50 ` [PATCH 0/3] Check enumeration before MSR save/restore Pawan Gupta
2022-09-17 11:42 ` Hans de Goede
2022-09-19 16:56 ` Pawan Gupta
2022-11-08 18:16 ` Hans de Goede
2022-11-08 18:26 ` Borislav Petkov
2022-11-08 18:55 ` Borislav Petkov
2022-11-08 22:07 ` Pawan Gupta
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