linux-kernel - Re: [PATCH 11/12] powerpc/pseries/svm: Force SWIOTLB for secure guests

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Message-Id: <87y32xzr8n.fsf@morokweng.localdomain>
Date:   Thu, 23 May 2019 02:15:04 -0300
From:   Thiago Jung Bauermann <bauerman@...ux.ibm.com>
To:     Christoph Hellwig <hch@....de>
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        Alexey Kardashevskiy <aik@...abs.ru>,
        Anshuman Khandual <anshuman.linux@...il.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Mike Anderson <andmike@...ux.ibm.com>,
        Paul Mackerras <paulus@...ba.org>,
        Ram Pai <linuxram@...ibm.com>,
        Claudio Carvalho <cclaudio@...ux.ibm.com>,
        Anshuman Khandual <khandual@...ux.vnet.ibm.com>
Subject: Re: [PATCH 11/12] powerpc/pseries/svm: Force SWIOTLB for secure guests


Hello Christoph,

Thanks for reviewing the patch!

Christoph Hellwig <hch@....de> writes:

>> diff --git a/arch/powerpc/include/asm/mem_encrypt.h b/arch/powerpc/include/asm/mem_encrypt.h
>> new file mode 100644
>> index 000000000000..45d5e4d0e6e0
>> --- /dev/null
>> +++ b/arch/powerpc/include/asm/mem_encrypt.h
>> @@ -0,0 +1,19 @@
>> +/* SPDX-License-Identifier: GPL-2.0+ */
>> +/*
>> + * SVM helper functions
>> + *
>> + * Copyright 2019 IBM Corporation
>> + */
>> +
>> +#ifndef _ASM_POWERPC_MEM_ENCRYPT_H
>> +#define _ASM_POWERPC_MEM_ENCRYPT_H
>> +
>> +#define sme_me_mask	0ULL
>> +
>> +static inline bool sme_active(void) { return false; }
>> +static inline bool sev_active(void) { return false; }
>> +
>> +int set_memory_encrypted(unsigned long addr, int numpages);
>> +int set_memory_decrypted(unsigned long addr, int numpages);
>> +
>> +#endif /* _ASM_POWERPC_MEM_ENCRYPT_H */
>
> S/390 seems to be adding a stub header just like this.  Can you please
> clean up the Kconfig and generic headers bits for memory encryption so
> that we don't need all this boilerplate code?

Yes, that's a good idea. Will do.

>>  config PPC_SVM
>>  	bool "Secure virtual machine (SVM) support for POWER"
>>  	depends on PPC_PSERIES
>> +	select SWIOTLB
>> +	select ARCH_HAS_MEM_ENCRYPT
>>  	default n
>
> n is the default default, no need to explictly specify it.

Indeed. Changed for the next version.

-- 
Thiago Jung Bauermann
IBM Linux Technology Center