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=-13.0 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=unavailable 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 57AB8C433E5 for ; Fri, 24 Jul 2020 16:05:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 38EFA2065E for ; Fri, 24 Jul 2020 16:05:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728320AbgGXQFC (ORCPT ); Fri, 24 Jul 2020 12:05:02 -0400 Received: from 8bytes.org ([81.169.241.247]:33000 "EHLO theia.8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728195AbgGXQEr (ORCPT ); Fri, 24 Jul 2020 12:04:47 -0400 Received: from cap.home.8bytes.org (p5b006776.dip0.t-ipconnect.de [91.0.103.118]) (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 5391CFF2; Fri, 24 Jul 2020 18:04:40 +0200 (CEST) From: Joerg Roedel To: x86@kernel.org Cc: Joerg Roedel , Joerg Roedel , Tom Lendacky , hpa@zytor.com, Andy Lutomirski , Dave Hansen , Peter Zijlstra , Jiri Slaby , Dan Williams , Juergen Gross , Kees Cook , David Rientjes , Cfir Cohen , Erdem Aktas , Masami Hiramatsu , Mike Stunes , Sean Christopherson , Martin Radev , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org Subject: [PATCH v5 74/75] x86/efi: Add GHCB mappings when SEV-ES is active Date: Fri, 24 Jul 2020 18:03:35 +0200 Message-Id: <20200724160336.5435-75-joro@8bytes.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200724160336.5435-1-joro@8bytes.org> References: <20200724160336.5435-1-joro@8bytes.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Tom Lendacky Calling down to EFI runtime services can result in the firmware performing VMGEXIT calls. The firmware is likely to use the GHCB of the OS (e.g., for setting EFI variables), so each GHCB in the system needs to be identity mapped in the EFI page tables, as unencrypted, to avoid page faults. Signed-off-by: Tom Lendacky [ jroedel@suse.de: Moved GHCB mapping loop to sev-es.c ] Signed-off-by: Joerg Roedel --- arch/x86/boot/compressed/sev-es.c | 1 + arch/x86/include/asm/sev-es.h | 2 ++ arch/x86/kernel/sev-es.c | 30 ++++++++++++++++++++++++++++++ arch/x86/platform/efi/efi_64.c | 10 ++++++++++ 4 files changed, 43 insertions(+) diff --git a/arch/x86/boot/compressed/sev-es.c b/arch/x86/boot/compressed/sev-es.c index 1ce144e0ddc3..b522c18c0588 100644 --- a/arch/x86/boot/compressed/sev-es.c +++ b/arch/x86/boot/compressed/sev-es.c @@ -12,6 +12,7 @@ */ #include "misc.h" +#include #include #include #include diff --git a/arch/x86/include/asm/sev-es.h b/arch/x86/include/asm/sev-es.h index 21fdee11ac83..f22c4531624c 100644 --- a/arch/x86/include/asm/sev-es.h +++ b/arch/x86/include/asm/sev-es.h @@ -101,11 +101,13 @@ static __always_inline void sev_es_nmi_complete(void) if (static_branch_unlikely(&sev_es_enable_key)) __sev_es_nmi_complete(); } +extern int __init sev_es_efi_map_ghcbs(pgd_t *pgd); #else static inline void sev_es_ist_enter(struct pt_regs *regs) { } static inline void sev_es_ist_exit(void) { } static inline int sev_es_setup_ap_jump_table(struct real_mode_header *rmh) { return 0; } static inline void sev_es_nmi_complete(void) { } +static inline int sev_es_efi_map_ghcbs(pgd_t *pgd) { return 0; } #endif #endif diff --git a/arch/x86/kernel/sev-es.c b/arch/x86/kernel/sev-es.c index 6db343bd0117..c5e0ceb099c2 100644 --- a/arch/x86/kernel/sev-es.c +++ b/arch/x86/kernel/sev-es.c @@ -495,6 +495,36 @@ int sev_es_setup_ap_jump_table(struct real_mode_header *rmh) return 0; } +/* + * This is needed by the OVMF UEFI firmware which will use whatever it finds in + * the GHCB MSR as its GHCB to talk to the hypervisor. So make sure the per-cpu + * runtime GHCBs used by the kernel are also mapped in the EFI page-table. + */ +int __init sev_es_efi_map_ghcbs(pgd_t *pgd) +{ + struct sev_es_runtime_data *data; + unsigned long address, pflags; + int cpu; + u64 pfn; + + if (!sev_es_active()) + return 0; + + pflags = _PAGE_NX | _PAGE_RW; + + for_each_possible_cpu(cpu) { + data = per_cpu(runtime_data, cpu); + + address = __pa(&data->ghcb_page); + pfn = address >> PAGE_SHIFT; + + if (kernel_map_pages_in_pgd(pgd, pfn, address, 1, pflags)) + return 1; + } + + return 0; +} + static enum es_result vc_handle_msr(struct ghcb *ghcb, struct es_em_ctxt *ctxt) { struct pt_regs *regs = ctxt->regs; diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c index 413583f904a6..bcf979c4aa10 100644 --- a/arch/x86/platform/efi/efi_64.c +++ b/arch/x86/platform/efi/efi_64.c @@ -47,6 +47,7 @@ #include #include #include +#include /* * We allocate runtime services regions top-down, starting from -4G, i.e. @@ -229,6 +230,15 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages) return 1; } + /* + * When SEV-ES is active, the GHCB as set by the kernel will be used + * by firmware. Create a 1:1 unencrypted mapping for each GHCB. + */ + if (sev_es_efi_map_ghcbs(pgd)) { + pr_err("Failed to create 1:1 mapping for the GHCBs!\n"); + return 1; + } + /* * When making calls to the firmware everything needs to be 1:1 * mapped and addressable with 32-bit pointers. Map the kernel -- 2.27.0