From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thiago Jung Bauermann Subject: [RFC PATCH 10/11] powerpc/svm: Force the use of bounce buffers Date: Thu, 23 Aug 2018 23:59:32 -0300 Message-ID: <20180824025933.24319-11-bauerman@linux.ibm.com> References: <20180824025933.24319-1-bauerman@linux.ibm.com> Return-path: In-Reply-To: <20180824025933.24319-1-bauerman@linux.ibm.com> Sender: linux-kernel-owner@vger.kernel.org To: linuxppc-dev@lists.ozlabs.org Cc: iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Alexey Kardashevskiy , Anshuman Khandual , Benjamin Herrenschmidt , Christoph Hellwig , Michael Ellerman , Mike Anderson , Paul Mackerras , Ram Pai , Anshuman Khandual , Thiago Jung Bauermann List-Id: iommu@lists.linux-foundation.org From: Anshuman Khandual 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 Signed-off-by: Thiago Jung Bauermann --- 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(); return 0;