From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f69.google.com (mail-lf0-f69.google.com [209.85.215.69]) by kanga.kvack.org (Postfix) with ESMTP id 6B0C26B0038 for ; Mon, 27 Feb 2017 12:53:36 -0500 (EST) Received: by mail-lf0-f69.google.com with SMTP id a6so3176713lfa.1 for ; Mon, 27 Feb 2017 09:53:36 -0800 (PST) Received: from mail.skyhub.de (mail.skyhub.de. [5.9.137.197]) by mx.google.com with ESMTP id n192si9224821lfn.1.2017.02.27.09.53.34 for ; Mon, 27 Feb 2017 09:53:34 -0800 (PST) Date: Mon, 27 Feb 2017 18:52:59 +0100 From: Borislav Petkov Subject: Re: [RFC PATCH v4 19/28] swiotlb: Add warnings for use of bounce buffers with SME Message-ID: <20170227175259.whl75utazbzxp7jo@pd.tnic> References: <20170216154158.19244.66630.stgit@tlendack-t1.amdoffice.net> <20170216154619.19244.76653.stgit@tlendack-t1.amdoffice.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20170216154619.19244.76653.stgit@tlendack-t1.amdoffice.net> Sender: owner-linux-mm@kvack.org List-ID: To: Tom Lendacky Cc: linux-arch@vger.kernel.org, linux-efi@vger.kernel.org, kvm@vger.kernel.org, linux-doc@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-mm@kvack.org, iommu@lists.linux-foundation.org, Rik van Riel , Radim =?utf-8?B?S3LEjW3DocWZ?= , Toshimitsu Kani , Arnd Bergmann , Jonathan Corbet , Matt Fleming , "Michael S. Tsirkin" , Joerg Roedel , Konrad Rzeszutek Wilk , Paolo Bonzini , Brijesh Singh , Ingo Molnar , Alexander Potapenko , Andy Lutomirski , "H. Peter Anvin" , Andrey Ryabinin , Thomas Gleixner , Larry Woodman , Dmitry Vyukov On Thu, Feb 16, 2017 at 09:46:19AM -0600, Tom Lendacky wrote: > Add warnings to let the user know when bounce buffers are being used for > DMA when SME is active. Since the bounce buffers are not in encrypted > memory, these notifications are to allow the user to determine some > appropriate action - if necessary. > > Signed-off-by: Tom Lendacky > --- > arch/x86/include/asm/mem_encrypt.h | 11 +++++++++++ > include/linux/dma-mapping.h | 11 +++++++++++ > include/linux/mem_encrypt.h | 6 ++++++ > lib/swiotlb.c | 3 +++ > 4 files changed, 31 insertions(+) > > diff --git a/arch/x86/include/asm/mem_encrypt.h b/arch/x86/include/asm/mem_encrypt.h > index 87e816f..5a17f1b 100644 > --- a/arch/x86/include/asm/mem_encrypt.h > +++ b/arch/x86/include/asm/mem_encrypt.h > @@ -26,6 +26,11 @@ static inline bool sme_active(void) > return (sme_me_mask) ? true : false; > } > > +static inline u64 sme_dma_mask(void) > +{ > + return ((u64)sme_me_mask << 1) - 1; > +} > + > void __init sme_early_encrypt(resource_size_t paddr, > unsigned long size); > void __init sme_early_decrypt(resource_size_t paddr, > @@ -53,6 +58,12 @@ static inline bool sme_active(void) > { > return false; > } > + > +static inline u64 sme_dma_mask(void) > +{ > + return 0ULL; > +} > + > #endif > > static inline void __init sme_early_encrypt(resource_size_t paddr, > diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h > index 10c5a17..130bef7 100644 > --- a/include/linux/dma-mapping.h > +++ b/include/linux/dma-mapping.h > @@ -10,6 +10,7 @@ > #include > #include > #include > +#include > > /** > * List of possible attributes associated with a DMA mapping. The semantics > @@ -557,6 +558,11 @@ static inline int dma_set_mask(struct device *dev, u64 mask) > > if (!dev->dma_mask || !dma_supported(dev, mask)) > return -EIO; > + > + if (sme_active() && (mask < sme_dma_mask())) > + dev_warn(dev, > + "SME is active, device will require DMA bounce buffers\n"); > + Yes, definitely _once() here. It could be extended later to be per-device if the need arises. Also, a bit above in this function, we test if (ops->set_dma_mask) so device drivers which supply even an empty ->set_dma_mask will circumvent this check. It probably doesn't matter all that much right now because the only driver I see right now defining this method, though, is ethernet/intel/fm10k/fm10k_pf.c and some other arches' functionality which is unrelated here. But still... -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org