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From: Thomas Gleixner <tglx@linutronix.de>
To: Balbir Singh <sblbir@amazon.com>, linux-kernel@vger.kernel.org
Cc: jpoimboe@redhat.com, tony.luck@intel.com, keescook@chromium.org,
	benh@kernel.crashing.org, x86@kernel.org, dave.hansen@intel.com,
	thomas.lendacky@amd.com, Balbir Singh <sblbir@amazon.com>
Subject: Re: [PATCH v6 3/6] arch/x86/mm: Refactor cond_ibpb() to support other use cases
Date: Wed, 13 May 2020 16:16:16 +0200	[thread overview]
Message-ID: <87h7wj3opb.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20200510014803.12190-4-sblbir@amazon.com>

Balbir Singh <sblbir@amazon.com> writes:
> @@ -550,8 +549,10 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
>  		 * Avoid user/user BTB poisoning by flushing the branch
>  		 * predictor when switching between processes. This stops
>  		 * one process from doing Spectre-v2 attacks on another.
> +		 * The hook can also be used for mitigations that rely
> +		 * on switch_mm for hooks.

The new function name has absolutely nothing to do with IBPB and is
clearly talking about mitigations. So the IBPB comment wants to move and
that extra sentence you bolted on can go away. It's nonsensical word
salad anyway.
>  
>  	/* Reinitialize tlbstate. */
> -	this_cpu_write(cpu_tlbstate.last_user_mm_ibpb, LAST_USER_MM_IBPB);
> +	this_cpu_write(cpu_tlbstate.last_user_mm_spec, LAST_USER_MM_IBPB);

There is still no comment why this only needs MM_IBPB. I'll change this
to LAST_USER_MM_INIT and put that define close to the others.

Thanks,

        tglx

  reply	other threads:[~2020-05-13 14:16 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-10  1:47 [PATCH v6 0/6] Optionally flush L1D on context switch Balbir Singh
2020-05-10  1:47 ` [PATCH v6 1/6] arch/x86/kvm: Refactor l1d flush lifecycle management Balbir Singh
2020-05-13 13:35   ` Thomas Gleixner
2020-05-14  8:23     ` Singh, Balbir
2020-05-13 13:53   ` Thomas Gleixner
2020-05-14  8:25     ` Singh, Balbir
2020-05-22  9:32   ` [tip: x86/mm] x86/kvm: Refactor L1D flush page management tip-bot2 for Balbir Singh
2020-05-10  1:47 ` [PATCH v6 2/6] arch/x86/kvm: Refactor tlbflush and l1d flush Balbir Singh
2020-05-22  9:32   ` [tip: x86/mm] x86/kvm: Refactor L1D flush operations tip-bot2 for Balbir Singh
2020-05-10  1:48 ` [PATCH v6 3/6] arch/x86/mm: Refactor cond_ibpb() to support other use cases Balbir Singh
2020-05-13 14:16   ` Thomas Gleixner [this message]
2020-05-22  9:32   ` [tip: x86/mm] x86/mm: " tip-bot2 for Balbir Singh
2020-09-16 13:11   ` [tip: x86/pti] " tip-bot2 for Balbir Singh
2020-05-10  1:48 ` [PATCH v6 4/6] arch/x86/kvm: Refactor L1D flushing Balbir Singh
2020-05-22  9:32   ` [tip: x86/mm] x86/kvm: " tip-bot2 for Balbir Singh
2020-05-10  1:48 ` [PATCH v6 5/6] Optionally flush L1D on context switch Balbir Singh
2020-05-13 15:04   ` Thomas Gleixner
2020-05-14  8:23     ` Singh, Balbir
2020-05-13 15:27   ` Thomas Gleixner
2020-05-14 21:28     ` Singh, Balbir
2020-05-13 16:16   ` Thomas Gleixner
2020-05-14  7:43     ` Singh, Balbir
2020-05-14 11:33       ` Thomas Gleixner
2020-05-10  1:48 ` [PATCH v6 6/6] Documentation: Add L1D flushing Documentation Balbir Singh
2020-05-13 13:33   ` Thomas Gleixner
2020-05-14  1:12     ` Singh, Balbir

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