From 77bd2342d4304bda7896c953d424d15deb314ca3 Mon Sep 17 00:00:00 2001 From: Tom Lendacky Date: Mon, 17 Jul 2017 16:10:19 -0500 Subject: [PATCH] x86/mm: Add support for changing the memory encryption attribute MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add support for changing the memory encryption attribute for one or more memory pages. This will be useful when we have to change the AP trampoline area to not be encrypted. Or when we need to change the SWIOTLB area to not be encrypted in support of devices that can't support the encryption mask range. Signed-off-by: Tom Lendacky Reviewed-by: Thomas Gleixner Reviewed-by: Borislav Petkov Cc: Alexander Potapenko Cc: Andrey Ryabinin Cc: Andy Lutomirski Cc: Arnd Bergmann Cc: Borislav Petkov Cc: Brijesh Singh Cc: Dave Young Cc: Dmitry Vyukov Cc: Jonathan Corbet Cc: Konrad Rzeszutek Wilk Cc: Larry Woodman Cc: Linus Torvalds Cc: Matt Fleming Cc: Michael S. Tsirkin Cc: Paolo Bonzini Cc: Peter Zijlstra Cc: Radim Krčmář Cc: Rik van Riel Cc: Toshimitsu Kani Cc: kasan-dev@googlegroups.com Cc: kvm@vger.kernel.org Cc: linux-arch@vger.kernel.org Cc: linux-doc@vger.kernel.org Cc: linux-efi@vger.kernel.org Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/924ae0d1f6d4c90c5a0e366c291b90a2d86aa79e.1500319216.git.thomas.lendacky@amd.com Signed-off-by: Ingo Molnar --- arch/x86/include/asm/set_memory.h | 3 ++ arch/x86/mm/pageattr.c | 62 +++++++++++++++++++++++++++++++ 2 files changed, 65 insertions(+) diff --git a/arch/x86/include/asm/set_memory.h b/arch/x86/include/asm/set_memory.h index eaec6c364e42..cd71273ec49d 100644 --- a/arch/x86/include/asm/set_memory.h +++ b/arch/x86/include/asm/set_memory.h @@ -11,6 +11,7 @@ * Executability : eXeutable, NoteXecutable * Read/Write : ReadOnly, ReadWrite * Presence : NotPresent + * Encryption : Encrypted, Decrypted * * Within a category, the attributes are mutually exclusive. * @@ -42,6 +43,8 @@ int set_memory_wt(unsigned long addr, int numpages); int set_memory_wb(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 7e2d6c0a64c4..9c8ea129ff5c 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -1775,6 +1775,68 @@ 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 SME is not active */ + if (!sme_active()) + return 0; + + /* Should not be working on unaligned addresses */ + if (WARN_ONCE(addr & ~PAGE_MASK, "misaligned address: %#lx\n", addr)) + addr &= PAGE_MASK; + + 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; + + /* 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); + + 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; +} + +int set_memory_encrypted(unsigned long addr, int numpages) +{ + return __set_memory_enc_dec(addr, numpages, true); +} + +int set_memory_decrypted(unsigned long addr, int numpages) +{ + return __set_memory_enc_dec(addr, numpages, false); +} + int set_pages_uc(struct page *page, int numpages) { unsigned long addr = (unsigned long)page_address(page);