From: Thiago Jung Bauermann <bauerman@linux.ibm.com>
To: Christoph Hellwig <hch@lst.de>
Cc: linuxppc-dev@lists.ozlabs.org, iommu@lists.linux-foundation.org,
linux-kernel@vger.kernel.org,
Alexey Kardashevskiy <aik@ozlabs.ru>,
Anshuman Khandual <anshuman.linux@gmail.com>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Mike Anderson <andmike@linux.ibm.com>,
Paul Mackerras <paulus@samba.org>, Ram Pai <linuxram@us.ibm.com>,
Anshuman Khandual <khandual@linux.vnet.ibm.com>
Subject: Re: [RFC PATCH 10/11] powerpc/svm: Force the use of bounce buffers
Date: Fri, 24 Aug 2018 20:38:54 -0300 [thread overview]
Message-ID: <87o9drxrld.fsf@morokweng.localdomain> (raw)
In-Reply-To: <20180824060055.GB13689@lst.de>
Hello Christoph,
Thanks for your quick review.
Christoph Hellwig <hch@lst.de> writes:
> On Thu, Aug 23, 2018 at 11:59:32PM -0300, Thiago Jung Bauermann wrote:
>> From: Anshuman Khandual <khandual@linux.vnet.ibm.com>
>>
>> SWIOTLB checks range of incoming CPU addresses to be bounced and see if the
>> device can access it through it's DMA window without requiring bouncing. In
>> such cases it just chooses to skip bouncing. But for cases like secure
>> guests on powerpc platform all addresses need to be bounced into the shared
>> pool of memory because the host cannot access it otherwise. Hence the need
>> to do the bouncing is not related to device's DMA window. Hence force the
>> use of bouncing by setting the swiotlb_force variable on secure guests.
>>
>> Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
>> Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
>> ---
>> arch/powerpc/kernel/svm.c | 1 +
>> 1 file changed, 1 insertion(+)
>>
>> diff --git a/arch/powerpc/kernel/svm.c b/arch/powerpc/kernel/svm.c
>> index 1af5caa955f5..f0576ad65cd0 100644
>> --- a/arch/powerpc/kernel/svm.c
>> +++ b/arch/powerpc/kernel/svm.c
>> @@ -17,6 +17,7 @@ static int __init init_svm(void)
>> return 0;
>>
>> ppc_swiotlb_enable = 1;
>> + swiotlb_force = SWIOTLB_FORCE;
>> swiotlb_update_mem_attributes();
>
> This needs a comment.
Good point. Will add one.
If in the new scheme of things (with bus_dma_mask?) dma_capable() on a
virtio device running in a secure guest returns false, then this patch
becomes unnecessary and can be dropped.
--
Thiago Jung Bauermann
IBM Linux Technology Center
next prev parent reply other threads:[~2018-08-24 23:38 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-24 2:59 [RFC PATCH 00/11] Secure Virtual Machine Enablement Thiago Jung Bauermann
2018-08-24 2:59 ` [RFC PATCH 01/11] powerpc/svm: Detect Secure Virtual Machine (SVM) platform Thiago Jung Bauermann
2018-08-24 2:59 ` [RFC PATCH 02/11] powerpc/svm: Select CONFIG_DMA_DIRECT_OPS and CONFIG_SWIOTLB Thiago Jung Bauermann
2018-08-24 2:59 ` [RFC PATCH 03/11] powerpc/svm: Add memory conversion (shared/secure) helper functions Thiago Jung Bauermann
2018-08-24 2:59 ` [RFC PATCH 04/11] powerpc/svm: Convert SWIOTLB buffers to shared memory Thiago Jung Bauermann
2018-08-24 2:59 ` [RFC PATCH 05/11] powerpc/svm: Don't release SWIOTLB buffers on secure guests Thiago Jung Bauermann
2018-08-24 2:59 ` [RFC PATCH 06/11] powerpc/svm: Use SWIOTLB DMA API for all virtio devices Thiago Jung Bauermann
2018-08-24 2:59 ` [RFC PATCH 07/11] powerpc/svm: Use shared memory for Debug Trace Log (DTL) Thiago Jung Bauermann
2018-08-24 2:59 ` [RFC PATCH 08/11] powerpc: Add and use LPPACA_SIZE constant Thiago Jung Bauermann
2018-08-24 2:59 ` [RFC PATCH 09/11] powerpc/svm: Use shared memory for LPPACA structures Thiago Jung Bauermann
2018-08-24 2:59 ` [RFC PATCH 10/11] powerpc/svm: Force the use of bounce buffers Thiago Jung Bauermann
[not found] ` <20180824025933.24319-11-bauerman-tEXmvtCZX7AybS5Ee8rs3A@public.gmane.org>
2018-08-24 6:00 ` Christoph Hellwig
2018-08-24 23:38 ` Thiago Jung Bauermann [this message]
2018-08-24 2:59 ` [RFC PATCH 11/11] powerpc/svm: Increase SWIOTLB buffer size Thiago Jung Bauermann
[not found] ` <20180824025933.24319-12-bauerman-tEXmvtCZX7AybS5Ee8rs3A@public.gmane.org>
2018-08-25 8:55 ` Christoph Hellwig
[not found] ` <20180824025933.24319-1-bauerman-tEXmvtCZX7AybS5Ee8rs3A@public.gmane.org>
2018-08-24 6:00 ` [RFC PATCH 00/11] Secure Virtual Machine Enablement Christoph Hellwig
2018-08-24 16:25 Thiago Jung Bauermann
2018-08-24 16:25 ` [RFC PATCH 10/11] powerpc/svm: Force the use of bounce buffers Thiago Jung Bauermann
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