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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, 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 37199C4332D for ; Thu, 19 Mar 2020 09:14:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0BD8420740 for ; Thu, 19 Mar 2020 09:14:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727407AbgCSJOj (ORCPT ); Thu, 19 Mar 2020 05:14:39 -0400 Received: from 8bytes.org ([81.169.241.247]:51930 "EHLO theia.8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727380AbgCSJOi (ORCPT ); Thu, 19 Mar 2020 05:14:38 -0400 Received: by theia.8bytes.org (Postfix, from userid 1000) id 9D5BD768; Thu, 19 Mar 2020 10:14:23 +0100 (CET) From: Joerg Roedel To: x86@kernel.org Cc: hpa@zytor.com, Andy Lutomirski , Dave Hansen , Peter Zijlstra , Thomas Hellstrom , Jiri Slaby , Dan Williams , Tom Lendacky , Juergen Gross , Kees Cook , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, Joerg Roedel , Joerg Roedel Subject: [PATCH 39/70] x86/sev-es: Setup GHCB based boot #VC handler Date: Thu, 19 Mar 2020 10:13:36 +0100 Message-Id: <20200319091407.1481-40-joro@8bytes.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200319091407.1481-1-joro@8bytes.org> References: <20200319091407.1481-1-joro@8bytes.org> Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: Joerg Roedel Add the infrastructure to handle #VC exceptions when the kernel runs on virtual addresses and has a GHCB mapped. This handler will be used until the runtime #VC handler takes over. Signed-off-by: Joerg Roedel --- arch/x86/include/asm/segment.h | 2 +- arch/x86/include/asm/sev-es.h | 1 + arch/x86/kernel/head64.c | 6 ++ arch/x86/kernel/sev-es-shared.c | 14 ++-- arch/x86/kernel/sev-es.c | 116 ++++++++++++++++++++++++++++++++ arch/x86/mm/extable.c | 1 + 6 files changed, 132 insertions(+), 8 deletions(-) diff --git a/arch/x86/include/asm/segment.h b/arch/x86/include/asm/segment.h index 6669164abadc..5b648066504c 100644 --- a/arch/x86/include/asm/segment.h +++ b/arch/x86/include/asm/segment.h @@ -230,7 +230,7 @@ #define NUM_EXCEPTION_VECTORS 32 /* Bitmask of exception vectors which push an error code on the stack: */ -#define EXCEPTION_ERRCODE_MASK 0x00027d00 +#define EXCEPTION_ERRCODE_MASK 0x20027d00 #define GDT_SIZE (GDT_ENTRIES*8) #define GDT_ENTRY_TLS_ENTRIES 3 diff --git a/arch/x86/include/asm/sev-es.h b/arch/x86/include/asm/sev-es.h index caa29f75ce41..122b3e71a788 100644 --- a/arch/x86/include/asm/sev-es.h +++ b/arch/x86/include/asm/sev-es.h @@ -76,5 +76,6 @@ static inline u64 copy_lower_bits(u64 out, u64 in, unsigned int bits) } extern void early_vc_handler(void); +extern bool boot_vc_exception(struct pt_regs *regs); #endif diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index b8613fc0a364..850c435b9fa5 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -386,6 +386,12 @@ void __init early_exception(struct pt_regs *regs, int trapnr) early_make_pgtable(native_read_cr2())) return; +#ifdef CONFIG_AMD_MEM_ENCRYPT + if (trapnr == X86_TRAP_VC && + boot_vc_exception(regs)) + return; +#endif + early_fixup_exception(regs, trapnr); } diff --git a/arch/x86/kernel/sev-es-shared.c b/arch/x86/kernel/sev-es-shared.c index 7a6e4db669f0..b178a2db61a7 100644 --- a/arch/x86/kernel/sev-es-shared.c +++ b/arch/x86/kernel/sev-es-shared.c @@ -9,7 +9,7 @@ * and is included directly into both code-bases. */ -static void __maybe_unused sev_es_terminate(unsigned int reason) +static void sev_es_terminate(unsigned int reason) { /* Request Guest Termination from Hypvervisor */ sev_es_wr_ghcb_msr(GHCB_SEV_TERMINATE); @@ -19,7 +19,7 @@ static void __maybe_unused sev_es_terminate(unsigned int reason) asm volatile("hlt\n" : : : "memory"); } -static bool __maybe_unused sev_es_negotiate_protocol(void) +static bool sev_es_negotiate_protocol(void) { u64 val; @@ -38,7 +38,7 @@ static bool __maybe_unused sev_es_negotiate_protocol(void) return true; } -static void __maybe_unused vc_ghcb_invalidate(struct ghcb *ghcb) +static void vc_ghcb_invalidate(struct ghcb *ghcb) { memset(ghcb->save.valid_bitmap, 0, sizeof(ghcb->save.valid_bitmap)); } @@ -50,9 +50,9 @@ static bool vc_decoding_needed(unsigned long exit_code) exit_code <= SVM_EXIT_LAST_EXCP); } -static enum es_result __maybe_unused vc_init_em_ctxt(struct es_em_ctxt *ctxt, - struct pt_regs *regs, - unsigned long exit_code) +static enum es_result vc_init_em_ctxt(struct es_em_ctxt *ctxt, + struct pt_regs *regs, + unsigned long exit_code) { enum es_result ret = ES_OK; @@ -65,7 +65,7 @@ static enum es_result __maybe_unused vc_init_em_ctxt(struct es_em_ctxt *ctxt, return ret; } -static void __maybe_unused vc_finish_insn(struct es_em_ctxt *ctxt) +static void vc_finish_insn(struct es_em_ctxt *ctxt) { ctxt->regs->ip += ctxt->insn.length; } diff --git a/arch/x86/kernel/sev-es.c b/arch/x86/kernel/sev-es.c index 27fdef6b3700..c17980e8db78 100644 --- a/arch/x86/kernel/sev-es.c +++ b/arch/x86/kernel/sev-es.c @@ -7,7 +7,9 @@ * Author: Joerg Roedel */ +#include /* For show_regs() */ #include +#include #include #include @@ -15,8 +17,21 @@ #include #include #include +#include #include +/* For early boot hypervisor communication in SEV-ES enabled guests */ +struct ghcb boot_ghcb_page __bss_decrypted __aligned(PAGE_SIZE); + +/* + * Needs to be in the .data section because we need it NULL before bss is + * cleared + */ +struct ghcb __initdata *boot_ghcb; + +/* Needed in vc_early_vc_forward_exception */ +extern void early_exception(struct pt_regs *regs, int trapnr); + static inline u64 sev_es_rd_ghcb_msr(void) { return native_read_msr(MSR_AMD64_SEV_ES_GHCB); @@ -160,3 +175,104 @@ static enum es_result vc_read_mem(struct es_em_ctxt *ctxt, /* Include code shared with pre-decompression boot stage */ #include "sev-es-shared.c" + +/* + * This function runs on the first #VC exception after the kernel + * switched to virtual addresses. + */ +static bool __init sev_es_setup_ghcb(void) +{ + /* First make sure the hypervisor talks a supported protocol. */ + if (!sev_es_negotiate_protocol()) + return false; + /* + * Clear the boot_ghcb. The first exception comes in before the bss + * section is cleared. + */ + memset(&boot_ghcb_page, 0, PAGE_SIZE); + + /* Alright - Make the boot-ghcb public */ + boot_ghcb = &boot_ghcb_page; + + return true; +} + +static void __init vc_early_vc_forward_exception(struct es_em_ctxt *ctxt) +{ + int trapnr = ctxt->fi.vector; + + if (trapnr == X86_TRAP_PF) + native_write_cr2(ctxt->fi.cr2); + + ctxt->regs->orig_ax = ctxt->fi.error_code; + early_exception(ctxt->regs, trapnr); +} + +static enum es_result vc_handle_exitcode(struct es_em_ctxt *ctxt, + struct ghcb *ghcb, + unsigned long exit_code) +{ + enum es_result result; + + switch (exit_code) { + default: + /* + * Unexpected #VC exception + */ + result = ES_UNSUPPORTED; + } + + return result; +} + +bool __init boot_vc_exception(struct pt_regs *regs) +{ + unsigned long exit_code = regs->orig_ax; + struct es_em_ctxt ctxt; + enum es_result result; + + /* Do initial setup or terminate the guest */ + if (unlikely(boot_ghcb == NULL && !sev_es_setup_ghcb())) + sev_es_terminate(GHCB_SEV_ES_REASON_GENERAL_REQUEST); + + vc_ghcb_invalidate(boot_ghcb); + result = vc_init_em_ctxt(&ctxt, regs, exit_code); + + if (result == ES_OK) + result = vc_handle_exitcode(&ctxt, boot_ghcb, exit_code); + + /* Done - now check the result */ + switch (result) { + case ES_OK: + vc_finish_insn(&ctxt); + break; + case ES_UNSUPPORTED: + early_printk("PANIC: Unsupported exit-code 0x%02lx in early #VC exception (IP: 0x%lx)\n", + exit_code, regs->ip); + goto fail; + case ES_VMM_ERROR: + early_printk("PANIC: Failure in communication with VMM (exit-code 0x%02lx IP: 0x%lx)\n", + exit_code, regs->ip); + goto fail; + case ES_DECODE_FAILED: + early_printk("PANIC: Failed to decode instruction (exit-code 0x%02lx IP: 0x%lx)\n", + exit_code, regs->ip); + goto fail; + case ES_EXCEPTION: + vc_early_vc_forward_exception(&ctxt); + break; + case ES_RETRY: + /* Nothing to do */ + break; + default: + BUG(); + } + + return true; + +fail: + show_regs(regs); + + while (true) + halt(); +} diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c index 30bb0bd3b1b8..cd440a9cf422 100644 --- a/arch/x86/mm/extable.c +++ b/arch/x86/mm/extable.c @@ -5,6 +5,7 @@ #include #include +#include #include #include -- 2.17.1