From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tom Lendacky Subject: Re: [RFC PATCH v2 07/20] x86: Provide general kernel support for memory encryption Date: Wed, 7 Sep 2016 09:30:54 -0500 Message-ID: References: <20160822223529.29880.50884.stgit@tlendack-t1.amdoffice.net> <20160822223646.29880.28794.stgit@tlendack-t1.amdoffice.net> <20160906093113.GA18319@pd.tnic> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20160906093113.GA18319-fF5Pk5pvG8Y@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Borislav Petkov Cc: linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kvm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Matt Fleming , x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, Alexander Potapenko , "H. Peter Anvin" , linux-arch-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Jonathan Corbet , linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kasan-dev-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org, Ingo Molnar , Andrey Ryabinin , Arnd Bergmann , Andy Lutomirski , Thomas Gleixner , Dmitry Vyukov , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, Paolo Bonzini List-Id: linux-efi@vger.kernel.org On 09/06/2016 04:31 AM, Borislav Petkov wrote: > On Mon, Aug 22, 2016 at 05:36:46PM -0500, Tom Lendacky wrote: >> Adding general kernel support for memory encryption includes: >> - Modify and create some page table macros to include the Secure Memory >> Encryption (SME) memory encryption mask >> - Update kernel boot support to call an SME routine that checks for and >> sets the SME capability (the SME routine will grow later and for now >> is just a stub routine) >> - Update kernel boot support to call an SME routine that encrypts the >> kernel (the SME routine will grow later and for now is just a stub >> routine) >> - Provide an SME initialization routine to update the protection map with >> the memory encryption mask so that it is used by default >> >> Signed-off-by: Tom Lendacky > > ... > >> diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c >> index 54a2372..88c7bae 100644 >> --- a/arch/x86/kernel/head64.c >> +++ b/arch/x86/kernel/head64.c >> @@ -28,6 +28,7 @@ >> #include >> #include >> #include >> +#include >> >> /* >> * Manage page tables very early on. >> @@ -42,7 +43,7 @@ static void __init reset_early_page_tables(void) >> { >> memset(early_level4_pgt, 0, sizeof(pgd_t)*(PTRS_PER_PGD-1)); >> next_early_pgt = 0; >> - write_cr3(__pa_nodebug(early_level4_pgt)); >> + write_cr3(__sme_pa_nodebug(early_level4_pgt)); >> } >> >> /* Create a new PMD entry */ >> @@ -54,7 +55,7 @@ int __init early_make_pgtable(unsigned long address) >> pmdval_t pmd, *pmd_p; >> >> /* Invalid address or early pgt is done ? */ >> - if (physaddr >= MAXMEM || read_cr3() != __pa_nodebug(early_level4_pgt)) >> + if (physaddr >= MAXMEM || read_cr3() != __sme_pa_nodebug(early_level4_pgt)) >> return -1; >> >> again: >> @@ -157,6 +158,11 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data) >> >> clear_page(init_level4_pgt); >> >> + /* Update the early_pmd_flags with the memory encryption mask */ >> + early_pmd_flags |= _PAGE_ENC; >> + >> + sme_early_init(); >> + > > So maybe this comes later but you're setting _PAGE_ENC unconditionally > *before* sme_early_init(). > > I think you should set it in sme_early_init() and iff SME is enabled. _PAGE_ENC is #defined as sme_me_mask and sme_me_mask has already been set (or not set) at this point - so it will be the mask if SME is active or 0 if SME is not active. sme_early_init() is merely propagating the mask to other structures. Since early_pmd_flags is mainly used in this file (one line in head_64.S is the other place) I felt it best to modify it here. But it can always be moved if you feel that is best. Thanks, Tom >