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 C6225C433EF for ; Tue, 5 Oct 2021 02:52:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AB45B6140A for ; Tue, 5 Oct 2021 02:52:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231645AbhJECyk (ORCPT ); Mon, 4 Oct 2021 22:54:40 -0400 Received: from mga01.intel.com ([192.55.52.88]:43315 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231588AbhJECyW (ORCPT ); Mon, 4 Oct 2021 22:54:22 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10127"; a="248894660" X-IronPort-AV: E=Sophos;i="5.85,347,1624345200"; d="scan'208";a="248894660" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Oct 2021 19:52:32 -0700 X-IronPort-AV: E=Sophos;i="5.85,347,1624345200"; d="scan'208";a="483409131" Received: from asaini1-mobl1.amr.corp.intel.com (HELO skuppusw-desk1.amr.corp.intel.com) ([10.251.138.96]) by fmsmga007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Oct 2021 19:52:31 -0700 From: Kuppuswamy Sathyanarayanan To: Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, Paolo Bonzini , David Hildenbrand , Andrea Arcangeli , Josh Poimboeuf , Juergen Gross , Deep Shah , VMware Inc , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel Cc: Peter H Anvin , Dave Hansen , Tony Luck , Dan Williams , Andi Kleen , Kirill Shutemov , Sean Christopherson , Kuppuswamy Sathyanarayanan , linux-kernel@vger.kernel.org Subject: [PATCH v8 09/11] x86/tdx: Add MSR support for TDX guest Date: Mon, 4 Oct 2021 19:52:03 -0700 Message-Id: <20211005025205.1784480-10-sathyanarayanan.kuppuswamy@linux.intel.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20211005025205.1784480-1-sathyanarayanan.kuppuswamy@linux.intel.com> References: <20211005025205.1784480-1-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" Use hypercall to emulate MSR read/write for TDX platform. TDVMCALL[Instruction.RDMSR] and TDVMCALL[Instruction.WRMSR] provide MSR oprations. RDMSR and WRMSR specification details can be found in Guest-Host-Communication Interface (GHCI) for Intel Trust Domain Extensions (Intel TDX) specification, sec titled "TDG.VP. VMCALL" and "TDG.VP.VMCALL". Signed-off-by: Kirill A. Shutemov Reviewed-by: Andi Kleen Reviewed-by: Tony Luck Signed-off-by: Kuppuswamy Sathyanarayanan --- Changes since v7: * Removed tdx_is_context_switched_msr() support (since the list is incomplete). * Added section title to spec reference. Changes since v6: * None Changes since v5: * Renamed "tdg" prefix with "tdx". * Added comments for _tdx_hypercall() usage in MSR read/write functions. Change since v4: * Removed You usage from commit log. Changes since v3: * None arch/x86/kernel/tdx.c | 53 +++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 51 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/tdx.c b/arch/x86/kernel/tdx.c index 3d0416515506..062ac4720434 100644 --- a/arch/x86/kernel/tdx.c +++ b/arch/x86/kernel/tdx.c @@ -110,6 +110,41 @@ static __cpuidle void tdx_safe_halt(void) _tdx_halt(irq_disabled, do_sti); } +static u64 tdx_read_msr_safe(unsigned int msr, int *err) +{ + struct tdx_hypercall_output out = {0}; + u64 ret; + + /* + * Emulate the MSR read via hypercall. More info about ABI + * can be found in TDX Guest-Host-Communication Interface + * (GHCI), sec titled "TDG.VP.VMCALL". + */ + ret = _tdx_hypercall(EXIT_REASON_MSR_READ, msr, 0, 0, 0, &out); + + *err = ret ? -EIO : 0; + + return out.r11; +} + +static int tdx_write_msr_safe(unsigned int msr, unsigned int low, + unsigned int high) +{ + u64 ret; + + WARN_ON_ONCE(tdx_is_context_switched_msr(msr)); + + /* + * Emulate the MSR write via hypercall. More info about ABI + * can be found in TDX Guest-Host-Communication Interface + * (GHCI) sec titled "TDG.VP.VMCALL". + */ + ret = _tdx_hypercall(EXIT_REASON_MSR_WRITE, msr, (u64)high << 32 | low, + 0, 0, NULL); + + return ret ? -EIO : 0; +} + unsigned long tdx_get_ve_info(struct ve_info *ve) { struct tdx_module_output out = {0}; @@ -136,19 +171,33 @@ unsigned long tdx_get_ve_info(struct ve_info *ve) int tdx_handle_virtualization_exception(struct pt_regs *regs, struct ve_info *ve) { + unsigned long val; + int ret = 0; + switch (ve->exit_reason) { case EXIT_REASON_HLT: tdx_halt(); break; + case EXIT_REASON_MSR_READ: + val = tdx_read_msr_safe(regs->cx, (unsigned int *)&ret); + if (!ret) { + regs->ax = (u32)val; + regs->dx = val >> 32; + } + break; + case EXIT_REASON_MSR_WRITE: + ret = tdx_write_msr_safe(regs->cx, regs->ax, regs->dx); + break; default: pr_warn("Unexpected #VE: %lld\n", ve->exit_reason); return -EFAULT; } /* After successful #VE handling, move the IP */ - regs->ip += ve->instr_len; + if (!ret) + regs->ip += ve->instr_len; - return 0; + return ret; } void __init tdx_early_init(void) -- 2.25.1