From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: [PATCH v4 75/75] x86/sev-es: Check required CPU features for SEV-ES Date: Tue, 14 Jul 2020 14:09:17 +0200 Message-ID: <20200714120917.11253-76-joro@8bytes.org> References: <20200714120917.11253-1-joro@8bytes.org> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20200714120917.11253-1-joro@8bytes.org> Sender: linux-kernel-owner@vger.kernel.org To: x86@kernel.org Cc: Joerg Roedel , Joerg Roedel , Martin Radev , hpa@zytor.com, Andy Lutomirski , Dave Hansen , Peter Zijlstra , Jiri Slaby , Dan Williams , Tom Lendacky , Juergen Gross , Kees Cook , David Rientjes , Cfir Cohen , Erdem Aktas , Masami Hiramatsu , Mike Stunes , Sean Christopherson , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org List-Id: virtualization@lists.linuxfoundation.org From: Martin Radev Make sure the machine supports RDRAND, otherwise there is no trusted source of of randomness in the system. Signed-off-by: Martin Radev Signed-off-by: Joerg Roedel --- arch/x86/boot/compressed/sev-es.c | 3 +++ arch/x86/kernel/sev-es-shared.c | 15 +++++++++++++++ arch/x86/kernel/sev-es.c | 3 +++ 3 files changed, 21 insertions(+) diff --git a/arch/x86/boot/compressed/sev-es.c b/arch/x86/boot/compressed/sev-es.c index b522c18c0588..eb1a8b5cc753 100644 --- a/arch/x86/boot/compressed/sev-es.c +++ b/arch/x86/boot/compressed/sev-es.c @@ -145,6 +145,9 @@ void sev_es_shutdown_ghcb(void) if (!boot_ghcb) return; + if (!sev_es_check_cpu_features()) + error("SEV-ES CPU Features missing."); + /* * GHCB Page must be flushed from the cache and mapped encrypted again. * Otherwise the running kernel will see strange cache effects when diff --git a/arch/x86/kernel/sev-es-shared.c b/arch/x86/kernel/sev-es-shared.c index 608f76d0d088..56de70cb80d8 100644 --- a/arch/x86/kernel/sev-es-shared.c +++ b/arch/x86/kernel/sev-es-shared.c @@ -9,6 +9,21 @@ * and is included directly into both code-bases. */ +#ifndef __BOOT_COMPRESSED +#define error(v) pr_err(v) +#define has_cpuflag(f) boot_cpu_has(f) +#endif + +static bool __init sev_es_check_cpu_features(void) +{ + if (!has_cpuflag(X86_FEATURE_RDRAND)) { + error("RDRAND instruction not supported - no trusted source of randomness available\n"); + return false; + } + + return true; +} + static void sev_es_terminate(unsigned int reason) { u64 val = GHCB_SEV_TERMINATE; diff --git a/arch/x86/kernel/sev-es.c b/arch/x86/kernel/sev-es.c index 61308f9c8138..481ea00c58b6 100644 --- a/arch/x86/kernel/sev-es.c +++ b/arch/x86/kernel/sev-es.c @@ -682,6 +682,9 @@ void __init sev_es_init_vc_handling(void) if (!sev_es_active()) return; + if (!sev_es_check_cpu_features()) + panic("SEV-ES CPU Features missing"); + /* Initialize per-cpu GHCB pages */ for_each_possible_cpu(cpu) { sev_es_alloc_runtime_data(cpu); -- 2.27.0