Messages in this thread | | | Date | Fri, 24 Aug 2018 08:00:55 +0200 | From | Christoph Hellwig <> | Subject | Re: [RFC PATCH 10/11] powerpc/svm: Force the use of bounce buffers |
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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.
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