Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Tue, 16 Feb 2021 13:10:25 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Nadav Amit <nadav.amit@gmail.com>
Cc:     Thomas Gleixner <tglx@linutronix.de>, linux-kernel@vger.kernel.org,
        Andy Lutomirski <luto@kernel.org>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Nadav Amit <namit@vmware.com>,
        "K. Y. Srinivasan" <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
        Stephen Hemminger <sthemmin@microsoft.com>,
        Sasha Levin <sashal@kernel.org>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        x86@kernel.org, Juergen Gross <jgross@suse.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        linux-hyperv@vger.kernel.org,
        virtualization@lists.linux-foundation.org, kvm@vger.kernel.org,
        xen-devel@lists.xenproject.org,
        Michael Kelley <mikelley@microsoft.com>
Subject: Re: [PATCH v5 4/8] x86/mm/tlb: Flush remote and local TLBs
 concurrently
Message-ID: <YCu2MQFdV4JTrUQb@hirez.programming.kicks-ass.net>
References: <20210209221653.614098-1-namit@vmware.com>
 <20210209221653.614098-5-namit@vmware.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20210209221653.614098-5-namit@vmware.com>
Precedence: bulk

On Tue, Feb 09, 2021 at 02:16:49PM -0800, Nadav Amit wrote:
> @@ -816,8 +821,8 @@ STATIC_NOPV void native_flush_tlb_others(const struct cpumask *cpumask,
>  	 * doing a speculative memory access.
>  	 */
>  	if (info->freed_tables) {
> -		smp_call_function_many(cpumask, flush_tlb_func,
> -			       (void *)info, 1);
> +		on_each_cpu_cond_mask(NULL, flush_tlb_func, (void *)info, true,
> +				      cpumask);
>  	} else {
>  		/*
>  		 * Although we could have used on_each_cpu_cond_mask(),
> @@ -844,14 +849,15 @@ STATIC_NOPV void native_flush_tlb_others(const struct cpumask *cpumask,
>  			if (tlb_is_not_lazy(cpu))
>  				__cpumask_set_cpu(cpu, cond_cpumask);
>  		}
> -		smp_call_function_many(cond_cpumask, flush_tlb_func, (void *)info, 1);
> +		on_each_cpu_cond_mask(NULL, flush_tlb_func, (void *)info, true,
> +				      cpumask);
>  	}
>  }

Surely on_each_cpu_mask() is more appropriate? There the compiler can do
the NULL propagation because it's on the same TU.

--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -821,8 +821,7 @@ STATIC_NOPV void native_flush_tlb_multi(
 	 * doing a speculative memory access.
 	 */
 	if (info->freed_tables) {
-		on_each_cpu_cond_mask(NULL, flush_tlb_func, (void *)info, true,
-				      cpumask);
+		on_each_cpu_mask(cpumask, flush_tlb_func, (void *)info, true);
 	} else {
 		/*
 		 * Although we could have used on_each_cpu_cond_mask(),
@@ -849,8 +848,7 @@ STATIC_NOPV void native_flush_tlb_multi(
 			if (tlb_is_not_lazy(cpu))
 				__cpumask_set_cpu(cpu, cond_cpumask);
 		}
-		on_each_cpu_cond_mask(NULL, flush_tlb_func, (void *)info, true,
-				      cpumask);
+		on_each_cpu_mask(cpumask, flush_tlb_func, (void *)info, true);
 	}
 }