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From: Peter Zijlstra <peterz@infradead.org>
To: Alison Schofield <alison.schofield@intel.com>
Cc: dhowells@redhat.com, tglx@linutronix.de, jmorris@namei.org,
	mingo@redhat.com, hpa@zytor.com, bp@alien8.de, luto@kernel.org,
	kirill.shutemov@linux.intel.com, dave.hansen@intel.com,
	kai.huang@intel.com, jun.nakajima@intel.com,
	dan.j.williams@intel.com, jarkko.sakkinen@intel.com,
	keyrings@vger.kernel.org, linux-security-module@vger.kernel.org,
	linux-mm@kvack.org, x86@kernel.org
Subject: Re: [RFC v2 11/13] keys/mktme: Program memory encryption keys on a system wide basis
Date: Tue, 4 Dec 2018 10:21:45 +0100
Message-ID: <20181204092145.GR11614@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <72dd5f38c1fdbc4c532f8caf2d2010f1ddfa8439.1543903910.git.alison.schofield@intel.com>

On Mon, Dec 03, 2018 at 11:39:58PM -0800, Alison Schofield wrote:

> +struct mktme_hw_program_info {
> +	struct mktme_key_program *key_program;
> +	unsigned long status;
> +};
> +
> +/* Program a KeyID on a single package. */
> +static void mktme_program_package(void *hw_program_info)
> +{
> +	struct mktme_hw_program_info *info = hw_program_info;
> +	int ret;
> +
> +	ret = mktme_key_program(info->key_program);
> +	if (ret != MKTME_PROG_SUCCESS)
> +		WRITE_ONCE(info->status, ret);

What's the purpose of that WRITE_ONCE()?

> +}
> +
> +/* Program a KeyID across the entire system. */
> +static int mktme_program_system(struct mktme_key_program *key_program,
> +				cpumask_var_t mktme_cpumask)
> +{
> +	struct mktme_hw_program_info info = {
> +		.key_program = key_program,
> +		.status = MKTME_PROG_SUCCESS,
> +	};
> +	get_online_cpus();
> +	on_each_cpu_mask(mktme_cpumask, mktme_program_package, &info, 1);
> +	put_online_cpus();
> +
> +	return info.status;
> +}
> +
>  /* Copy the payload to the HW programming structure and program this KeyID */
>  static int mktme_program_keyid(int keyid, struct mktme_payload *payload)
>  {
> @@ -84,7 +116,7 @@ static int mktme_program_keyid(int keyid, struct mktme_payload *payload)
>  			kprog->key_field_2[i] ^= kern_entropy[i];
>  		}
>  	}
> -	ret = mktme_key_program(kprog);
> +	ret = mktme_program_system(kprog, mktme_leadcpus);
>  	kmem_cache_free(mktme_prog_cache, kprog);
>  	return ret;
>  }
> @@ -299,6 +331,28 @@ struct key_type key_type_mktme = {
>  	.destroy	= mktme_destroy_key,
>  };
>  
> +static int mktme_build_leadcpus_mask(void)
> +{
> +	int online_cpu, mktme_cpu;
> +	int online_pkgid, mktme_pkgid = -1;
> +
> +	if (!zalloc_cpumask_var(&mktme_leadcpus, GFP_KERNEL))
> +		return -ENOMEM;
> +
> +	for_each_online_cpu(online_cpu) {
> +		online_pkgid = topology_physical_package_id(online_cpu);
> +
> +		for_each_cpu(mktme_cpu, mktme_leadcpus) {
> +			mktme_pkgid = topology_physical_package_id(mktme_cpu);
> +			if (mktme_pkgid == online_pkgid)
> +				break;
> +		}
> +		if (mktme_pkgid != online_pkgid)
> +			cpumask_set_cpu(online_cpu, mktme_leadcpus);

Do you really need LOCK prefixed bit set here?

> +	}
> +	return 0;
> +}

How is that serialized and kept relevant in the face of hotplug?

Also, do you really need O(n^2) to find the first occurence of a value
in an array?

  reply index

Thread overview: 91+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-04  7:39 [RFC v2 00/13] Multi-Key Total Memory Encryption API (MKTME) Alison Schofield
2018-12-04  7:39 ` [RFC v2 01/13] x86/mktme: Document the MKTME APIs Alison Schofield
2018-12-05 18:11   ` Andy Lutomirski
2018-12-05 19:22     ` Alison Schofield
2018-12-05 23:35       ` Andy Lutomirski
2018-12-06  8:04   ` Sakkinen, Jarkko
2018-12-04  7:39 ` [RFC v2 02/13] mm: Generalize the mprotect implementation to support extensions Alison Schofield
2018-12-06  8:08   ` Sakkinen, Jarkko
2018-12-04  7:39 ` [RFC v2 03/13] syscall/x86: Wire up a new system call for memory encryption keys Alison Schofield
2018-12-04  7:39 ` [RFC v2 04/13] x86/mm: Add helper functions for MKTME " Alison Schofield
2018-12-04  9:14   ` Peter Zijlstra
2018-12-05  5:49     ` Alison Schofield
2018-12-04 15:35   ` Andy Lutomirski
2018-12-05  5:52     ` Alison Schofield
2018-12-06  8:31   ` Sakkinen, Jarkko
2018-12-04  7:39 ` [RFC v2 05/13] x86/mm: Set KeyIDs in encrypted VMAs Alison Schofield
2018-12-06  8:37   ` Sakkinen, Jarkko
2018-12-04  7:39 ` [RFC v2 06/13] mm: Add the encrypt_mprotect() system call Alison Schofield
2018-12-06  8:38   ` Sakkinen, Jarkko
2018-12-04  7:39 ` [RFC v2 07/13] x86/mm: Add helpers for reference counting encrypted VMAs Alison Schofield
2018-12-04  8:58   ` Peter Zijlstra
2018-12-05  5:28     ` Alison Schofield
2018-12-04  7:39 ` [RFC v2 08/13] mm: Use reference counting for " Alison Schofield
2018-12-04  7:39 ` [RFC v2 09/13] mm: Restrict memory encryption to anonymous VMA's Alison Schofield
2018-12-04  9:10   ` Peter Zijlstra
2018-12-05  5:30     ` Alison Schofield
2018-12-05  9:07       ` Peter Zijlstra
2018-12-04  7:39 ` [RFC v2 10/13] keys/mktme: Add the MKTME Key Service type for memory encryption Alison Schofield
2018-12-06  8:51   ` Sakkinen, Jarkko
2018-12-06  8:54     ` Sakkinen, Jarkko
2018-12-06 15:11     ` Dave Hansen
2018-12-06 22:56       ` Sakkinen, Jarkko
2018-12-04  7:39 ` [RFC v2 11/13] keys/mktme: Program memory encryption keys on a system wide basis Alison Schofield
2018-12-04  9:21   ` Peter Zijlstra [this message]
2018-12-04  9:50     ` Kirill A. Shutemov
2018-12-05  5:44       ` Alison Schofield
2018-12-05  5:43     ` Alison Schofield
2018-12-05  9:10       ` Peter Zijlstra
2018-12-05 17:26         ` Alison Schofield
2018-12-04  7:39 ` [RFC v2 12/13] keys/mktme: Save MKTME data if kernel cmdline parameter allows Alison Schofield
2018-12-04  9:22   ` Peter Zijlstra
2018-12-07  2:14   ` Huang, Kai
2018-12-07  3:42     ` Alison Schofield
2018-12-07  6:39     ` Jarkko Sakkinen
2018-12-07  6:45       ` Jarkko Sakkinen
2018-12-07 11:47     ` Kirill A. Shutemov
2018-12-04  7:40 ` [RFC v2 13/13] keys/mktme: Support CPU Hotplug for MKTME keys Alison Schofield
2018-12-04  9:28   ` Peter Zijlstra
2018-12-05  5:32     ` Alison Schofield
2018-12-04  9:31   ` Peter Zijlstra
2018-12-05  5:36     ` Alison Schofield
2018-12-04  9:25 ` [RFC v2 00/13] Multi-Key Total Memory Encryption API (MKTME) Peter Zijlstra
2018-12-04  9:46   ` Kirill A. Shutemov
2018-12-05 20:32     ` Sakkinen, Jarkko
2018-12-06 11:22       ` Kirill A. Shutemov
2018-12-06 14:59         ` Dave Hansen
2018-12-07 10:12           ` Huang, Kai
2018-12-06 21:23         ` Sakkinen, Jarkko
2018-12-07 11:54           ` Kirill A. Shutemov
2018-12-04 19:19 ` Andy Lutomirski
2018-12-04 20:00   ` Andy Lutomirski
2018-12-04 20:32     ` Dave Hansen
2018-12-05 22:19   ` Sakkinen, Jarkko
2018-12-07  2:05     ` Huang, Kai
2018-12-07  6:48       ` Jarkko Sakkinen
2018-12-07 11:57     ` Kirill A. Shutemov
2018-12-07 21:59       ` Sakkinen, Jarkko
2018-12-07 23:45         ` Sakkinen, Jarkko
2018-12-07 23:48           ` Andy Lutomirski
2018-12-08  1:33           ` Huang, Kai
2018-12-08  3:53             ` Sakkinen, Jarkko
2018-12-12 15:31           ` Sakkinen, Jarkko
2018-12-12 16:29             ` Andy Lutomirski
2018-12-12 16:43               ` Sakkinen, Jarkko
2018-12-12 23:27                 ` Huang, Kai
2018-12-13  5:49                   ` Sakkinen, Jarkko
2018-12-13  5:52                     ` Sakkinen, Jarkko
2018-12-12 23:24               ` Huang, Kai
2018-12-07 23:35       ` Eric Rannaud
2018-12-05 23:49   ` Dave Hansen
2018-12-06  1:09     ` Andy Lutomirski
2018-12-06  1:25       ` Dan Williams
2018-12-06 15:39       ` Dave Hansen
2018-12-06 19:10         ` Andy Lutomirski
2018-12-06 19:31           ` Dave Hansen
2018-12-07  1:55       ` Huang, Kai
2018-12-07  4:23         ` Dave Hansen
2018-12-07 23:53         ` Andy Lutomirski
2018-12-08  1:11           ` Dave Hansen
2018-12-08  2:07           ` Huang, Kai
2018-12-05 20:30 ` Sakkinen, Jarkko

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