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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1CE91C433EF for ; Fri, 18 Feb 2022 16:19:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237884AbiBRQTQ (ORCPT ); Fri, 18 Feb 2022 11:19:16 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:42904 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237639AbiBRQR4 (ORCPT ); Fri, 18 Feb 2022 11:17:56 -0500 Received: from mga06.intel.com (mga06.intel.com [134.134.136.31]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 885283969B for ; Fri, 18 Feb 2022 08:17:26 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1645201046; x=1676737046; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=hz/kh0uvaCIxwsvfeV4VXQp/Vpt7YUdFG5ImQMhC4rQ=; b=PGJ+XaNv+fYDZnz2bYEu8QkDArB89IhQMMfUYDO19QzJDg4cr2y6bXgj ttyZPGZ0mdFrfV6KtyA5u38eHjk+ixFvKnsuulSXUiYn+lUiE8LyqZOSF mTlvsoXMjN5FhIW3/vrKAA8vX2DrBvFIh78oVRrKXm7mSNAkqt3dRFybc ffbImfvKoh/4xcLd3cACHfrEysK5YFq/TPpdk2VYSw1ER1VnqDE97BQvH 553JqT42bJ6v2XQY+0ONxpkwObdGYAsUdqB1qULolrT/sPoEZRWKCAJIC pCdF+DIEbVR0gdSqrDwq0sKcNXjJ1kCSqUiT7FB+2evL3umnWs9bUe2vg Q==; X-IronPort-AV: E=McAfee;i="6200,9189,10261"; a="311897901" X-IronPort-AV: E=Sophos;i="5.88,379,1635231600"; d="scan'208";a="311897901" Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Feb 2022 08:17:26 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.88,379,1635231600"; d="scan'208";a="775328282" Received: from black.fi.intel.com ([10.237.72.28]) by fmsmga006.fm.intel.com with ESMTP; 18 Feb 2022 08:17:20 -0800 Received: by black.fi.intel.com (Postfix, from userid 1000) id E123CAFD; Fri, 18 Feb 2022 18:17:22 +0200 (EET) From: "Kirill A. Shutemov" To: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@intel.com, luto@kernel.org, peterz@infradead.org Cc: sathyanarayanan.kuppuswamy@linux.intel.com, aarcange@redhat.com, ak@linux.intel.com, dan.j.williams@intel.com, david@redhat.com, hpa@zytor.com, jgross@suse.com, jmattson@google.com, joro@8bytes.org, jpoimboe@redhat.com, knsathya@kernel.org, pbonzini@redhat.com, sdeep@vmware.com, seanjc@google.com, tony.luck@intel.com, vkuznets@redhat.com, wanpengli@tencent.com, x86@kernel.org, linux-kernel@vger.kernel.org, "Kirill A . Shutemov" Subject: [PATCHv3 18/32] x86/tdx: Add port I/O emulation Date: Fri, 18 Feb 2022 19:17:04 +0300 Message-Id: <20220218161718.67148-19-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220218161718.67148-1-kirill.shutemov@linux.intel.com> References: <20220218161718.67148-1-kirill.shutemov@linux.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Kuppuswamy Sathyanarayanan TDX hypervisors cannot emulate instructions directly. This includes port I/O which is normally emulated in the hypervisor. All port I/O instructions inside TDX trigger the #VE exception in the guest and would be normally emulated there. Use a hypercall to emulate port I/O. Extend the tdx_handle_virt_exception() and add support to handle the #VE due to port I/O instructions. String I/O operations are not supported in TDX. Unroll them by declaring CC_ATTR_GUEST_UNROLL_STRING_IO confidential computing attribute. Signed-off-by: Kuppuswamy Sathyanarayanan Reviewed-by: Andi Kleen Reviewed-by: Dan Williams Signed-off-by: Kirill A. Shutemov --- arch/x86/coco/tdx.c | 54 +++++++++++++++++++++++++++++++++++ arch/x86/kernel/cc_platform.c | 7 ++++- 2 files changed, 60 insertions(+), 1 deletion(-) diff --git a/arch/x86/coco/tdx.c b/arch/x86/coco/tdx.c index 74ab7c5a767d..e3693d0494a7 100644 --- a/arch/x86/coco/tdx.c +++ b/arch/x86/coco/tdx.c @@ -19,6 +19,12 @@ #define EPT_READ 0 #define EPT_WRITE 1 +/* See Exit Qualification for I/O Instructions in VMX documentation */ +#define VE_IS_IO_IN(e) ((e) & BIT(3)) +#define VE_GET_IO_SIZE(e) (((e) & GENMASK(2, 0)) + 1) +#define VE_GET_PORT_NUM(e) ((e) >> 16) +#define VE_IS_IO_STRING(e) ((e) & BIT(4)) + static struct { unsigned int gpa_width; unsigned long attributes; @@ -292,6 +298,52 @@ static bool handle_mmio(struct pt_regs *regs, struct ve_info *ve) return true; } +/* + * Emulate I/O using hypercall. + * + * Assumes the IO instruction was using ax, which is enforced + * by the standard io.h macros. + * + * Return True on success or False on failure. + */ +static bool handle_io(struct pt_regs *regs, u32 exit_qual) +{ + struct tdx_hypercall_args args = { + .r10 = TDX_HYPERCALL_STANDARD, + .r11 = EXIT_REASON_IO_INSTRUCTION, + }; + int size, port; + u64 mask; + bool in, ret; + + if (VE_IS_IO_STRING(exit_qual)) + return false; + + in = VE_IS_IO_IN(exit_qual); + size = VE_GET_IO_SIZE(exit_qual); + port = VE_GET_PORT_NUM(exit_qual); + mask = GENMASK(BITS_PER_BYTE * size, 0); + + args.r12 = size; + args.r13 = !in; + args.r14 = port; + args.r15 = in ? 0 : regs->ax; + + /* + * Emulate the I/O read/write via hypercall. More info about + * ABI can be found in TDX Guest-Host-Communication Interface + * (GHCI) section titled "TDG.VP.VMCALL". + */ + ret = !__tdx_hypercall(&args, in ? TDX_HCALL_HAS_OUTPUT : 0); + if (!ret || !in) + return ret; + + regs->ax &= ~mask; + regs->ax |= ret ? args.r11 & mask : UINT_MAX; + + return ret; +} + void tdx_get_ve_info(struct ve_info *ve) { struct tdx_module_output out; @@ -347,6 +399,8 @@ static bool virt_exception_kernel(struct pt_regs *regs, struct ve_info *ve) return handle_cpuid(regs); case EXIT_REASON_EPT_VIOLATION: return handle_mmio(regs, ve); + case EXIT_REASON_IO_INSTRUCTION: + return handle_io(regs, ve->exit_qual); default: pr_warn("Unexpected #VE: %lld\n", ve->exit_reason); return false; diff --git a/arch/x86/kernel/cc_platform.c b/arch/x86/kernel/cc_platform.c index dba713c444ab..55128de5e27c 100644 --- a/arch/x86/kernel/cc_platform.c +++ b/arch/x86/kernel/cc_platform.c @@ -18,7 +18,12 @@ static enum cc_vendor cc_vendor; static bool intel_cc_platform_has(enum cc_attr attr) { - return false; + switch (attr) { + case CC_ATTR_GUEST_UNROLL_STRING_IO: + return true; + default: + return false; + } } /* -- 2.34.1