From mboxrd@z Thu Jan 1 00:00:00 1970 From: Borislav Petkov Subject: Re: [PATCH v5 32/32] x86/mm: Add support to make use of Secure Memory Encryption Date: Fri, 19 May 2017 13:27:03 +0200 Message-ID: <20170519112703.voajtn4t7uy6nwa3@pd.tnic> References: <20170418211612.10190.82788.stgit@tlendack-t1.amdoffice.net> <20170418212223.10190.85121.stgit@tlendack-t1.amdoffice.net> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Return-path: Content-Disposition: inline In-Reply-To: <20170418212223.10190.85121.stgit@tlendack-t1.amdoffice.net> Sender: owner-linux-mm@kvack.org 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, kexec@lists.infradead.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 , Larry Woodman , Brijesh Singh , Ingo Molnar , Andy Lutomirski , "H. Peter Anvin" , Andrey Ryabinin , Alexander List-Id: linux-efi@vger.kernel.org On Tue, Apr 18, 2017 at 04:22:23PM -0500, Tom Lendacky wrote: > Add support to check if SME has been enabled and if memory encryption > should be activated (checking of command line option based on the > configuration of the default state). If memory encryption is to be > activated, then the encryption mask is set and the kernel is encrypted > "in place." > > Signed-off-by: Tom Lendacky > --- > arch/x86/kernel/head_64.S | 1 + > arch/x86/mm/mem_encrypt.c | 83 +++++++++++++++++++++++++++++++++++++++++++-- > 2 files changed, 80 insertions(+), 4 deletions(-) ... > +unsigned long __init sme_enable(struct boot_params *bp) > { > + const char *cmdline_ptr, *cmdline_arg, *cmdline_on, *cmdline_off; > + unsigned int eax, ebx, ecx, edx; > + unsigned long me_mask; > + bool active_by_default; > + char buffer[16]; > + u64 msr; > + > + /* Check for the SME support leaf */ > + eax = 0x80000000; > + ecx = 0; > + native_cpuid(&eax, &ebx, &ecx, &edx); > + if (eax < 0x8000001f) > + goto out; > + > + /* > + * Check for the SME feature: > + * CPUID Fn8000_001F[EAX] - Bit 0 > + * Secure Memory Encryption support > + * CPUID Fn8000_001F[EBX] - Bits 5:0 > + * Pagetable bit position used to indicate encryption > + */ > + eax = 0x8000001f; > + ecx = 0; > + native_cpuid(&eax, &ebx, &ecx, &edx); > + if (!(eax & 1)) > + goto out; <---- newline here. > + me_mask = 1UL << (ebx & 0x3f); > + > + /* Check if SME is enabled */ > + msr = __rdmsr(MSR_K8_SYSCFG); > + if (!(msr & MSR_K8_SYSCFG_MEM_ENCRYPT)) > + goto out; > + > + /* > + * Fixups have not been applied to phys_base yet, so we must obtain > + * the address to the SME command line option data in the following > + * way. > + */ > + asm ("lea sme_cmdline_arg(%%rip), %0" > + : "=r" (cmdline_arg) > + : "p" (sme_cmdline_arg)); > + asm ("lea sme_cmdline_on(%%rip), %0" > + : "=r" (cmdline_on) > + : "p" (sme_cmdline_on)); > + asm ("lea sme_cmdline_off(%%rip), %0" > + : "=r" (cmdline_off) > + : "p" (sme_cmdline_off)); > + > + if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT)) > + active_by_default = true; > + else > + active_by_default = false; > + > + cmdline_ptr = (const char *)((u64)bp->hdr.cmd_line_ptr | > + ((u64)bp->ext_cmd_line_ptr << 32)); > + > + cmdline_find_option(cmdline_ptr, cmdline_arg, buffer, sizeof(buffer)); > + > + if (strncmp(buffer, cmdline_on, sizeof(buffer)) == 0) > + sme_me_mask = me_mask; Why doesn't simply if (!strncmp(buffer, "on", 2)) ... work? -- 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