From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f71.google.com (mail-lf0-f71.google.com [209.85.215.71]) by kanga.kvack.org (Postfix) with ESMTP id 6D7786B0038 for ; Wed, 22 Feb 2017 13:52:54 -0500 (EST) Received: by mail-lf0-f71.google.com with SMTP id a198so4897586lfb.6 for ; Wed, 22 Feb 2017 10:52:54 -0800 (PST) Received: from mail.skyhub.de (mail.skyhub.de. [5.9.137.197]) by mx.google.com with ESMTP id t20si1130037lff.308.2017.02.22.10.52.52 for ; Wed, 22 Feb 2017 10:52:52 -0800 (PST) Date: Wed, 22 Feb 2017 19:52:15 +0100 From: Borislav Petkov Subject: Re: [RFC PATCH v4 16/28] x86: Add support for changing memory encryption attribute Message-ID: <20170222185215.atbntnyw7252kkbk@pd.tnic> References: <20170216154158.19244.66630.stgit@tlendack-t1.amdoffice.net> <20170216154535.19244.6294.stgit@tlendack-t1.amdoffice.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20170216154535.19244.6294.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 09:45:35AM -0600, Tom Lendacky wrote: > Add support for changing the memory encryption attribute for one or more > memory pages. "This will be useful when we, ...., for example." > Signed-off-by: Tom Lendacky > --- > arch/x86/include/asm/cacheflush.h | 3 ++ > arch/x86/mm/pageattr.c | 66 +++++++++++++++++++++++++++++++++++++ > 2 files changed, 69 insertions(+) > > diff --git a/arch/x86/include/asm/cacheflush.h b/arch/x86/include/asm/cacheflush.h > index 872877d..33ae60a 100644 > --- a/arch/x86/include/asm/cacheflush.h > +++ b/arch/x86/include/asm/cacheflush.h > @@ -12,6 +12,7 @@ > * Executability : eXeutable, NoteXecutable > * Read/Write : ReadOnly, ReadWrite > * Presence : NotPresent > + * Encryption : Encrypted, Decrypted > * > * Within a category, the attributes are mutually exclusive. > * > @@ -47,6 +48,8 @@ > int set_memory_rw(unsigned long addr, int numpages); > int set_memory_np(unsigned long addr, int numpages); > int set_memory_4k(unsigned long addr, int numpages); > +int set_memory_encrypted(unsigned long addr, int numpages); > +int set_memory_decrypted(unsigned long addr, int numpages); > > int set_memory_array_uc(unsigned long *addr, int addrinarray); > int set_memory_array_wc(unsigned long *addr, int addrinarray); > diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c > index 91c5c63..9710f5c 100644 > --- a/arch/x86/mm/pageattr.c > +++ b/arch/x86/mm/pageattr.c > @@ -1742,6 +1742,72 @@ int set_memory_4k(unsigned long addr, int numpages) > __pgprot(0), 1, 0, NULL); > } > > +static int __set_memory_enc_dec(unsigned long addr, int numpages, bool enc) > +{ > + struct cpa_data cpa; > + unsigned long start; > + int ret; > + > + /* Nothing to do if the _PAGE_ENC attribute is zero */ > + if (_PAGE_ENC == 0) Why not: if (!sme_active()) ? > + return 0; > + > + /* Save original start address since it will be modified */ That's obvious - it is a small-enough function to fit on the screen. No need for the comment. > + start = addr; > + > + memset(&cpa, 0, sizeof(cpa)); > + cpa.vaddr = &addr; > + cpa.numpages = numpages; > + cpa.mask_set = enc ? __pgprot(_PAGE_ENC) : __pgprot(0); > + cpa.mask_clr = enc ? __pgprot(0) : __pgprot(_PAGE_ENC); > + cpa.pgd = init_mm.pgd; > + > + /* Should not be working on unaligned addresses */ > + if (WARN_ONCE(*cpa.vaddr & ~PAGE_MASK, > + "misaligned address: %#lx\n", *cpa.vaddr)) Use addr here so that you don't have to deref. gcc is probably smart enough but the code should look more readable this way too. > + *cpa.vaddr &= PAGE_MASK; I know, you must use cpa.vaddr here but if you move that alignment check over the cpa assignment, you can use addr solely. > + > + /* Must avoid aliasing mappings in the highmem code */ > + kmap_flush_unused(); > + vm_unmap_aliases(); > + > + /* > + * Before changing the encryption attribute, we need to flush caches. > + */ > + if (static_cpu_has(X86_FEATURE_CLFLUSH)) > + cpa_flush_range(start, numpages, 1); > + else > + cpa_flush_all(1); I guess we don't really need the distinction since a SME CPU most definitely implies CLFLUSH support but ok, let's be careful. > + > + ret = __change_page_attr_set_clr(&cpa, 1); > + > + /* > + * After changing the encryption attribute, we need to flush TLBs > + * again in case any speculative TLB caching occurred (but no need > + * to flush caches again). We could just use cpa_flush_all(), but > + * in case TLB flushing gets optimized in the cpa_flush_range() > + * path use the same logic as above. > + */ > + if (static_cpu_has(X86_FEATURE_CLFLUSH)) > + cpa_flush_range(start, numpages, 0); > + else > + cpa_flush_all(0); > + > + return ret; > +} -- 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