From: hpa@zytor.com
To: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bp@suse.de>,
Ricardo Neri <ricardo.neri-calderon@linux.intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>, Andy Lutomirski <luto@kernel.org>,
x86@kernel.org, "Peter Zijlstra (Intel)" <peterz@infradead.org>,
Dave Hansen <dave.hansen@intel.com>,
Tony Luck <tony.luck@intel.com>,
Cathy Zhang <cathy.zhang@intel.com>,
Fenghua Yu <fenghua.yu@intel.com>,
Kyung Min Park <kyung.min.park@intel.com>,
"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
Sean Christopherson <sean.j.christopherson@intel.com>,
linux-kernel@vger.kernel.org,
Ricardo Neri <ricardo.neri@intel.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
linux-edac@vger.kernel.org
Subject: Re: [PATCH v2] x86/cpu: Use SERIALIZE in sync_core() when available
Date: Tue, 04 Aug 2020 22:10:22 -0700 [thread overview]
Message-ID: <2511352F-5D28-4337-A4A2-1B54073F1F72@zytor.com> (raw)
In-Reply-To: <20200805050808.GC9127@nazgul.tnic>
On August 4, 2020 10:08:08 PM PDT, Borislav Petkov <bp@alien8.de> wrote:
>On Tue, Aug 04, 2020 at 09:58:25PM -0700, hpa@zytor.com wrote:
>> Because why use an alternative to jump over one instruction?
>>
>> I personally would prefer to have the IRET put out of line
>
>Can't yet - SERIALIZE CPUs are a minority at the moment.
>
>> and have the call/jmp replaced by SERIALIZE inline.
>
>Well, we could do:
>
> alternative_io("... IRET bunch", __ASM_SERIALIZE,
>X86_FEATURE_SERIALIZE, ...);
>
>and avoid all kinds of jumping. Alternatives get padded so there
>would be a couple of NOPs following when SERIALIZE gets patched in
>but it shouldn't be a problem. I guess one needs to look at what gcc
>generates...
I didn't say behind a trap. IRET is a control transfer instruction, and slow, so putting it out of line really isn't unreasonable. Can even do a call to a common handler.
--
Sent from my Android device with K-9 Mail. Please excuse my brevity.
next prev parent reply other threads:[~2020-08-05 5:12 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-05 2:10 Ricardo Neri
2020-08-05 4:48 ` Borislav Petkov
2020-08-05 4:58 ` hpa
2020-08-05 5:08 ` Borislav Petkov
2020-08-05 5:10 ` hpa [this message]
2020-08-05 17:07 ` Ricardo Neri
2020-08-05 18:28 ` Andy Lutomirski
2020-08-05 19:11 ` Ricardo Neri
2020-08-05 20:30 ` Andy Lutomirski
2020-08-05 22:19 ` Luck, Tony
2020-08-05 15:54 ` Ricardo Neri
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