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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6F960C433F5 for ; Tue, 5 Oct 2021 20:42:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4E86D610C8 for ; Tue, 5 Oct 2021 20:42:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236474AbhJEUoL (ORCPT ); Tue, 5 Oct 2021 16:44:11 -0400 Received: from mga07.intel.com ([134.134.136.100]:11170 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230019AbhJEUny (ORCPT ); Tue, 5 Oct 2021 16:43:54 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10128"; a="289354605" X-IronPort-AV: E=Sophos;i="5.85,349,1624345200"; d="scan'208";a="289354605" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Oct 2021 13:42:02 -0700 X-IronPort-AV: E=Sophos;i="5.85,349,1624345200"; d="scan'208";a="523979583" Received: from alyee-mobl.amr.corp.intel.com (HELO skuppusw-desk1.amr.corp.intel.com) ([10.254.5.222]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Oct 2021 13:42:01 -0700 From: Kuppuswamy Sathyanarayanan To: Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, Paolo Bonzini , David Hildenbrand , Andrea Arcangeli , Josh Poimboeuf , "H . Peter Anvin" Cc: Dave Hansen , Tony Luck , Dan Williams , Andi Kleen , Kirill Shutemov , Sean Christopherson , Kuppuswamy Sathyanarayanan , linux-kernel@vger.kernel.org Subject: [PATCH v7 07/10] x86/insn-eval: Introduce insn_decode_mmio() Date: Tue, 5 Oct 2021 13:41:33 -0700 Message-Id: <20211005204136.1812078-8-sathyanarayanan.kuppuswamy@linux.intel.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20211005204136.1812078-1-sathyanarayanan.kuppuswamy@linux.intel.com> References: <20211005204136.1812078-1-sathyanarayanan.kuppuswamy@linux.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Kirill A. Shutemov" In preparation for sharing MMIO instruction decode between SEV-ES and TDX, factor out the common decode into a new insn_decode_mmio() helper. For regular virtual machine, MMIO is handled by the VMM and KVM emulates instructions that caused MMIO. But, this model doesn't work for a secure VMs (like SEV or TDX) as VMM doesn't have access to the guest memory and register state. So, for TDX or SEV VMM needs assistance in handling MMIO. It induces exception in the guest. Guest has to decode the instruction and handle it on its own. The code is based on the current SEV MMIO implementation. Signed-off-by: Kirill A. Shutemov Reviewed-by: Andi Kleen Reviewed-by: Tony Luck Signed-off-by: Kuppuswamy Sathyanarayanan --- Changes since v6: * None Changes since v5: * None Changes since v4: * None Changes since v3: * None Changes since v2: * None arch/x86/include/asm/insn-eval.h | 12 +++++ arch/x86/lib/insn-eval.c | 82 ++++++++++++++++++++++++++++++++ 2 files changed, 94 insertions(+) diff --git a/arch/x86/include/asm/insn-eval.h b/arch/x86/include/asm/insn-eval.h index 041f399153b9..4a4ca7e7be66 100644 --- a/arch/x86/include/asm/insn-eval.h +++ b/arch/x86/include/asm/insn-eval.h @@ -29,4 +29,16 @@ int insn_fetch_from_user_inatomic(struct pt_regs *regs, bool insn_decode_from_regs(struct insn *insn, struct pt_regs *regs, unsigned char buf[MAX_INSN_SIZE], int buf_size); +enum mmio_type { + MMIO_DECODE_FAILED, + MMIO_WRITE, + MMIO_WRITE_IMM, + MMIO_READ, + MMIO_READ_ZERO_EXTEND, + MMIO_READ_SIGN_EXTEND, + MMIO_MOVS, +}; + +enum mmio_type insn_decode_mmio(struct insn *insn, int *bytes); + #endif /* _ASM_X86_INSN_EVAL_H */ diff --git a/arch/x86/lib/insn-eval.c b/arch/x86/lib/insn-eval.c index fbaa3fa24bde..2ab29d8d6731 100644 --- a/arch/x86/lib/insn-eval.c +++ b/arch/x86/lib/insn-eval.c @@ -1559,3 +1559,85 @@ bool insn_decode_from_regs(struct insn *insn, struct pt_regs *regs, return true; } + +/** + * insn_decode_mmio() - Decode a MMIO instruction + * @insn: Structure to store decoded instruction + * @bytes: Returns size of memory operand + * + * Decodes instruction that used for Memory-mapped I/O. + * + * Returns: + * + * Type of the instruction. Size of the memory operand is stored in + * @bytes. If decode failed, MMIO_DECODE_FAILED returned. + */ +enum mmio_type insn_decode_mmio(struct insn *insn, int *bytes) +{ + int type = MMIO_DECODE_FAILED; + + *bytes = 0; + + insn_get_opcode(insn); + switch (insn->opcode.bytes[0]) { + case 0x88: /* MOV m8,r8 */ + *bytes = 1; + fallthrough; + case 0x89: /* MOV m16/m32/m64, r16/m32/m64 */ + if (!*bytes) + *bytes = insn->opnd_bytes; + type = MMIO_WRITE; + break; + + case 0xc6: /* MOV m8, imm8 */ + *bytes = 1; + fallthrough; + case 0xc7: /* MOV m16/m32/m64, imm16/imm32/imm64 */ + if (!*bytes) + *bytes = insn->opnd_bytes; + type = MMIO_WRITE_IMM; + break; + + case 0x8a: /* MOV r8, m8 */ + *bytes = 1; + fallthrough; + case 0x8b: /* MOV r16/r32/r64, m16/m32/m64 */ + if (!*bytes) + *bytes = insn->opnd_bytes; + type = MMIO_READ; + break; + + case 0xa4: /* MOVS m8, m8 */ + *bytes = 1; + fallthrough; + case 0xa5: /* MOVS m16/m32/m64, m16/m32/m64 */ + if (!*bytes) + *bytes = insn->opnd_bytes; + type = MMIO_MOVS; + break; + + case 0x0f: /* Two-byte instruction */ + switch (insn->opcode.bytes[1]) { + case 0xb6: /* MOVZX r16/r32/r64, m8 */ + *bytes = 1; + fallthrough; + case 0xb7: /* MOVZX r32/r64, m16 */ + if (!*bytes) + *bytes = 2; + type = MMIO_READ_ZERO_EXTEND; + break; + + case 0xbe: /* MOVSX r16/r32/r64, m8 */ + *bytes = 1; + fallthrough; + case 0xbf: /* MOVSX r32/r64, m16 */ + if (!*bytes) + *bytes = 2; + type = MMIO_READ_SIGN_EXTEND; + break; + } + break; + } + + return type; +} -- 2.25.1