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Date: Mon, 7 Sep 2020 15:16:09 +0200 From: Joerg Roedel <joro@...tes.org> To: x86@...nel.org Cc: Joerg Roedel <joro@...tes.org>, Joerg Roedel <jroedel@...e.de>, Kees Cook <keescook@...omium.org>, hpa@...or.com, Andy Lutomirski <luto@...nel.org>, Dave Hansen <dave.hansen@...ux.intel.com>, Peter Zijlstra <peterz@...radead.org>, Jiri Slaby <jslaby@...e.cz>, Dan Williams <dan.j.williams@...el.com>, Tom Lendacky <thomas.lendacky@....com>, Juergen Gross <jgross@...e.com>, David Rientjes <rientjes@...gle.com>, Cfir Cohen <cfir@...gle.com>, Erdem Aktas <erdemaktas@...gle.com>, Masami Hiramatsu <mhiramat@...nel.org>, Mike Stunes <mstunes@...are.com>, Sean Christopherson <sean.j.christopherson@...el.com>, Martin Radev <martin.b.radev@...il.com>, linux-kernel@...r.kernel.org, kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org Subject: [PATCH v7 68/72] x86/head/64: Don't call verify_cpu() on starting APs From: Joerg Roedel <jroedel@...e.de> The APs are not ready to handle exceptions when verify_cpu() is called in secondary_startup_64. Signed-off-by: Joerg Roedel <jroedel@...e.de> Reviewed-by: Kees Cook <keescook@...omium.org> --- arch/x86/include/asm/realmode.h | 1 + arch/x86/kernel/head_64.S | 12 ++++++++++++ arch/x86/realmode/init.c | 6 ++++++ 3 files changed, 19 insertions(+) diff --git a/arch/x86/include/asm/realmode.h b/arch/x86/include/asm/realmode.h index 4d4d853f6841..5db5d083c873 100644 --- a/arch/x86/include/asm/realmode.h +++ b/arch/x86/include/asm/realmode.h @@ -72,6 +72,7 @@ extern unsigned char startup_32_smp[]; extern unsigned char boot_gdt[]; #else extern unsigned char secondary_startup_64[]; +extern unsigned char secondary_startup_64_no_verify[]; #endif static inline size_t real_mode_size_needed(void) diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index 41057ff79284..d976a9e6fcba 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -125,6 +125,18 @@ SYM_CODE_START(secondary_startup_64) /* Sanitize CPU configuration */ call verify_cpu + /* + * The secondary_startup_64_no_verify entry point is only used by + * SEV-ES guests. In those guests the call to verify_cpu() would cause + * #VC exceptions which can not be handled at this stage of secondary + * CPU bringup. + * + * All non SEV-ES systems, especially Intel systems, need to execute + * verify_cpu() above to make sure NX is enabled. + */ +SYM_INNER_LABEL(secondary_startup_64_no_verify, SYM_L_GLOBAL) + UNWIND_HINT_EMPTY + /* * Retrieve the modifier (SME encryption mask if SME is active) to be * added to the initial pgdir entry that will be programmed into CR3. diff --git a/arch/x86/realmode/init.c b/arch/x86/realmode/init.c index 3fb9b60be07a..22fda7d99159 100644 --- a/arch/x86/realmode/init.c +++ b/arch/x86/realmode/init.c @@ -46,6 +46,12 @@ static void sme_sev_setup_real_mode(struct trampoline_header *th) th->flags |= TH_FLAGS_SME_ACTIVE; if (sev_es_active()) { + /* + * Skip the call to verify_cpu() in secondary_startup_64 as it + * will cause #VC exceptions when the AP can't handle them yet. + */ + th->start = (u64) secondary_startup_64_no_verify; + if (sev_es_setup_ap_jump_table(real_mode_header)) panic("Failed to get/update SEV-ES AP Jump Table"); } -- 2.28.0
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