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Subject: Re: [PATCH 15/24] x86/mm: Allow flushing for future ASID switches
To: Peter Zijlstra <peterz@infradead.org>
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Cc: Ingo Molnar <mingo@kernel.org>, linux-kernel@vger.kernel.org,
        Andy Lutomirski <luto@amacapital.net>,
        Thomas Gleixner <tglx@linutronix.de>,
        "H . Peter Anvin" <hpa@zytor.com>, Borislav Petkov <bp@alien8.de>,
        Linus Torvalds <torvalds@linux-foundation.org>
From: Dave Hansen <dave.hansen@linux.intel.com>
Message-ID: <31ed5412-ac29-64fa-4435-144d310fb1b1@linux.intel.com>
Date: Thu, 30 Nov 2017 11:00:06 -0800
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On 11/30/2017 10:55 AM, Peter Zijlstra wrote:
>> __flush_tlb() does a flushing CR3 write that flushes the current PCID.
>> If we need other PCIDs flushed, we have to do it via the
>> tlb_flush_shared_nonglobals() mechanism.
> But the thing is, you _cannot_ have PCID enabled in that branch.

Is there some hardware limitation that I'm missing?