From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A21A6C433E2 for ; Mon, 7 Sep 2020 13:18:51 +0000 (UTC) Received: from silver.osuosl.org (smtp3.osuosl.org [140.211.166.136]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 597D3215A4 for ; Mon, 7 Sep 2020 13:18:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 597D3215A4 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=8bytes.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=virtualization-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by silver.osuosl.org (Postfix) with ESMTP id E195020525; Mon, 7 Sep 2020 13:18:50 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from silver.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id mkku0gZNs6h0; Mon, 7 Sep 2020 13:18:38 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by silver.osuosl.org (Postfix) with ESMTP id 0ADCB2151F; Mon, 7 Sep 2020 13:17:27 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id E7C09C0894; Mon, 7 Sep 2020 13:17:26 +0000 (UTC) Received: from silver.osuosl.org (smtp3.osuosl.org [140.211.166.136]) by lists.linuxfoundation.org (Postfix) with ESMTP id 04FA4C0051 for ; Mon, 7 Sep 2020 13:17:26 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by silver.osuosl.org (Postfix) with ESMTP id ECBB621509 for ; Mon, 7 Sep 2020 13:17:25 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from silver.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id rbB9JvTBNszC for ; Mon, 7 Sep 2020 13:17:12 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from theia.8bytes.org (8bytes.org [81.169.241.247]) by silver.osuosl.org (Postfix) with ESMTPS id 0D25C21515 for ; Mon, 7 Sep 2020 13:16:56 +0000 (UTC) Received: from cap.home.8bytes.org (p549add56.dip0.t-ipconnect.de [84.154.221.86]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (No client certificate requested) by theia.8bytes.org (Postfix) with ESMTPSA id 5F07FF84; Mon, 7 Sep 2020 15:16:53 +0200 (CEST) From: Joerg Roedel To: x86@kernel.org Subject: [PATCH v7 22/72] x86/boot/compressed/64: Add set_page_en/decrypted() helpers Date: Mon, 7 Sep 2020 15:15:23 +0200 Message-Id: <20200907131613.12703-23-joro@8bytes.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200907131613.12703-1-joro@8bytes.org> References: <20200907131613.12703-1-joro@8bytes.org> MIME-Version: 1.0 Cc: Juergen Gross , Tom Lendacky , Joerg Roedel , Mike Stunes , Kees Cook , kvm@vger.kernel.org, Peter Zijlstra , Cfir Cohen , Joerg Roedel , Dave Hansen , linux-kernel@vger.kernel.org, Sean Christopherson , virtualization@lists.linux-foundation.org, Martin Radev , Masami Hiramatsu , Andy Lutomirski , hpa@zytor.com, Erdem Aktas , David Rientjes , Dan Williams , Jiri Slaby X-BeenThere: virtualization@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Linux virtualization List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" From: Joerg Roedel The functions are needed to map the GHCB for SEV-ES guests. The GHCB is used for communication with the hypervisor, so its content must not be encrypted. After the GHCB is not needed anymore it must be mapped encrypted again so that the running kernel image can safely re-use the memory. Signed-off-by: Joerg Roedel --- arch/x86/boot/compressed/ident_map_64.c | 133 ++++++++++++++++++++++++ arch/x86/boot/compressed/misc.h | 2 + 2 files changed, 135 insertions(+) diff --git a/arch/x86/boot/compressed/ident_map_64.c b/arch/x86/boot/compressed/ident_map_64.c index aa91bebc0fe9..05742f641a06 100644 --- a/arch/x86/boot/compressed/ident_map_64.c +++ b/arch/x86/boot/compressed/ident_map_64.c @@ -24,6 +24,7 @@ /* These actually do the work of building the kernel identity maps. */ #include +#include #include #include #include @@ -165,6 +166,138 @@ void finalize_identity_maps(void) write_cr3(top_level_pgt); } +static pte_t *split_large_pmd(struct x86_mapping_info *info, + pmd_t *pmdp, unsigned long __address) +{ + unsigned long page_flags; + unsigned long address; + pte_t *pte; + pmd_t pmd; + int i; + + pte = (pte_t *)info->alloc_pgt_page(info->context); + if (!pte) + return NULL; + + address = __address & PMD_MASK; + /* No large page - clear PSE flag */ + page_flags = info->page_flag & ~_PAGE_PSE; + + /* Populate the PTEs */ + for (i = 0; i < PTRS_PER_PMD; i++) { + set_pte(&pte[i], __pte(address | page_flags)); + address += PAGE_SIZE; + } + + /* + * Ideally we need to clear the large PMD first and do a TLB + * flush before we write the new PMD. But the 2M range of the + * PMD might contain the code we execute and/or the stack + * we are on, so we can't do that. But that should be safe here + * because we are going from large to small mappings and we are + * also the only user of the page-table, so there is no chance + * of a TLB multihit. + */ + pmd = __pmd((unsigned long)pte | info->kernpg_flag); + set_pmd(pmdp, pmd); + /* Flush TLB to establish the new PMD */ + write_cr3(top_level_pgt); + + return pte + pte_index(__address); +} + +static void clflush_page(unsigned long address) +{ + unsigned int flush_size; + char *cl, *start, *end; + + /* + * Hardcode cl-size to 64 - CPUID can't be used here because that might + * cause another #VC exception and the GHCB is not ready to use yet. + */ + flush_size = 64; + start = (char *)(address & PAGE_MASK); + end = start + PAGE_SIZE; + + /* + * First make sure there are no pending writes on the cache-lines to + * flush. + */ + asm volatile("mfence" : : : "memory"); + + for (cl = start; cl != end; cl += flush_size) + clflush(cl); +} + +static int set_clr_page_flags(struct x86_mapping_info *info, + unsigned long address, + pteval_t set, pteval_t clr) +{ + pgd_t *pgdp = (pgd_t *)top_level_pgt; + p4d_t *p4dp; + pud_t *pudp; + pmd_t *pmdp; + pte_t *ptep, pte; + + /* + * First make sure there is a PMD mapping for 'address'. + * It should already exist, but keep things generic. + * + * To map the page just read from it and fault it in if there is no + * mapping yet. add_identity_map() can't be called here because that + * would unconditionally map the address on PMD level, destroying any + * PTE-level mappings that might already exist. Use assembly here so + * the access won't be optimized away. + */ + asm volatile("mov %[address], %%r9" + :: [address] "g" (*(unsigned long *)address) + : "r9", "memory"); + + /* + * The page is mapped at least with PMD size - so skip checks and walk + * directly to the PMD. + */ + p4dp = p4d_offset(pgdp, address); + pudp = pud_offset(p4dp, address); + pmdp = pmd_offset(pudp, address); + + if (pmd_large(*pmdp)) + ptep = split_large_pmd(info, pmdp, address); + else + ptep = pte_offset_kernel(pmdp, address); + + if (!ptep) + return -ENOMEM; + + /* + * Changing encryption attributes of a page requires to flush it from + * the caches. + */ + if ((set | clr) & _PAGE_ENC) + clflush_page(address); + + /* Update PTE */ + pte = *ptep; + pte = pte_set_flags(pte, set); + pte = pte_clear_flags(pte, clr); + set_pte(ptep, pte); + + /* Flush TLB after changing encryption attribute */ + write_cr3(top_level_pgt); + + return 0; +} + +int set_page_decrypted(unsigned long address) +{ + return set_clr_page_flags(&mapping_info, address, 0, _PAGE_ENC); +} + +int set_page_encrypted(unsigned long address) +{ + return set_clr_page_flags(&mapping_info, address, _PAGE_ENC, 0); +} + static void do_pf_error(const char *msg, unsigned long error_code, unsigned long address, unsigned long ip) { diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h index eaa8b45ebccb..01c0fb3417ca 100644 --- a/arch/x86/boot/compressed/misc.h +++ b/arch/x86/boot/compressed/misc.h @@ -98,6 +98,8 @@ static inline void choose_random_location(unsigned long input, #endif #ifdef CONFIG_X86_64 +extern int set_page_decrypted(unsigned long address); +extern int set_page_encrypted(unsigned long address); extern unsigned char _pgtable[]; #endif -- 2.28.0 _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization