From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it0-f71.google.com (mail-it0-f71.google.com [209.85.214.71]) by kanga.kvack.org (Postfix) with ESMTP id 5D07B44060D for ; Fri, 17 Feb 2017 11:01:03 -0500 (EST) Received: by mail-it0-f71.google.com with SMTP id h10so30972243ith.2 for ; Fri, 17 Feb 2017 08:01:03 -0800 (PST) Received: from userp1040.oracle.com (userp1040.oracle.com. [156.151.31.81]) by mx.google.com with ESMTPS id s67si1668356itb.40.2017.02.17.08.00.42 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 17 Feb 2017 08:00:42 -0800 (PST) Date: Fri, 17 Feb 2017 10:59:55 -0500 From: Konrad Rzeszutek Wilk Subject: Re: [RFC PATCH v4 19/28] swiotlb: Add warnings for use of bounce buffers with SME Message-ID: <20170217155955.GK30272@char.us.ORACLE.com> 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=us-ascii 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 , Paolo Bonzini , Brijesh Singh , Ingo Molnar , Alexander Potapenko , Andy Lutomirski , "H. Peter Anvin" , Borislav Petkov , 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"); You can make it one line. But I am wondering if you should use printk_ratelimit as this may fill the console up. > + > *dev->dma_mask = mask; > return 0; > } > @@ -576,6 +582,11 @@ static inline int dma_set_coherent_mask(struct device *dev, u64 mask) > { > if (!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"); Ditto. > + > dev->coherent_dma_mask = mask; > return 0; > } > diff --git a/include/linux/mem_encrypt.h b/include/linux/mem_encrypt.h > index 14a7b9f..6829ff1 100644 > --- a/include/linux/mem_encrypt.h > +++ b/include/linux/mem_encrypt.h > @@ -28,6 +28,12 @@ static inline bool sme_active(void) > { > return false; > } > + > +static inline u64 sme_dma_mask(void) > +{ > + return 0ULL; > +} > + > #endif > > #endif /* CONFIG_AMD_MEM_ENCRYPT */ > diff --git a/lib/swiotlb.c b/lib/swiotlb.c > index c463067..aff9353 100644 > --- a/lib/swiotlb.c > +++ b/lib/swiotlb.c > @@ -509,6 +509,9 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev, > if (no_iotlb_memory) > panic("Can not allocate SWIOTLB buffer earlier and can't now provide you with the DMA bounce buffer"); > > + WARN_ONCE(sme_active(), > + "SME is active and system is using DMA bounce buffers\n"); How does that help? As in what can the user do with this? > + > mask = dma_get_seg_boundary(hwdev); > > tbl_dma_addr &= mask; > -- 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