From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2583318FC9A; Thu, 8 Aug 2024 15:43:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723131807; cv=none; b=W84e669A1mZDXSiSKBaYKGUZrMx3WJZfyBG8nmVqg3RN4Sz0n1eqvoudYIfGA6VFX+vUsLdDf03pA5ARg6M3D1lwFgRaBLJhF+cqUu8XfdP4WDlmjCg4ppANvTB0E1dadjO5rnvt84nZsxzjiFLn0w8KltVwrJoKU+OZXWK4PFo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723131807; c=relaxed/simple; bh=sBNWmAsl748mI6sZ5oeJJ5R2kmjFzD4s7IW0KxK/il8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=tTGDMlqw/rWhCIlK78xxtR55j/yCINLAPGmA9USnV7N02xqjuSa7SN65J2HI5OL67nl4OdGrqSmWw4ZWKQNgkrhfKFQUxDriPaamFn+5ureqX4KNOSG7oQcqGDFS/nNM5Qd5qIbRBZzYpbliTSkpydPUxaW3IS7lZLztGZPn50A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=O/rg45xc; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="O/rg45xc" Received: by smtp.kernel.org (Postfix) with ESMTPSA id ED8E7C4AF0D; Thu, 8 Aug 2024 15:43:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1723131806; bh=sBNWmAsl748mI6sZ5oeJJ5R2kmjFzD4s7IW0KxK/il8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=O/rg45xcVymZlv8kQrmuAWcZdXcLpQCEKNVRMdK56kisTZWqkeWWKAZAmpOKHV2Ok hZT2msqP0Y474oRflWmHww0wLEY8I02uriCZXR66AL3zThGKbC/cV4cu0NL42sSV8o s2a7TILdETHKw4lz238R3obFSKuXN7gEAPgtklHf4XNxAlrDLB4rqv6aWQFsqyXHF1 LRBs1+CM9cPhPKlgCeXhsGcxmU2vycuHMgaAkN+Me5S3XNTRePhdng4LtjAU7NUUMV BhE/Te2Nv8W583rf+5VK9mUIlgO+oZeSjQnIRM0vubgzLiWK/4SFgrXIjVZjLK+oGQ TYG+y4jUNAA1Q== From: "Alexey Gladkov (Intel)" To: linux-kernel@vger.kernel.org, linux-coco@lists.linux.dev Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , "Kirill A. Shutemov" , Andrew Morton , Yuan Yao , Geert Uytterhoeven , Yuntao Wang , Kai Huang , Baoquan He , Oleg Nesterov , cho@microsoft.com, decui@microsoft.com, John.Starks@microsoft.com Subject: [PATCH v3 6/7] x86/tdx: Add a restriction on access to MMIO address Date: Thu, 8 Aug 2024 17:42:46 +0200 Message-ID: <89033a0cb3ed3ef4c48db7bc712ec2ea3a956524.1723130802.git.legion@kernel.org> X-Mailer: git-send-email 2.45.2 In-Reply-To: <6f989aea155817ef2f8a5fd2240ccff3f74d4edd.1722862355.git.legion@kernel.org> References: <83c9b05e7d359c0486a061f3bd31920ddb5c33a0.camel@intel.com> <6f989aea155817ef2f8a5fd2240ccff3f74d4edd.1722862355.git.legion@kernel.org> Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit In the case of userspace MMIO, if the user instruction + MAX_INSN_SIZE straddles page, then the "fetch" in the kernel could trigger a #VE. In this case the kernel would handle this second #VE as a !user_mode() MMIO. That way, additional address verifications can be avoided. The scenario of accessing userspace MMIO addresses from kernelspace does not seem appropriate under normal circumstances. Until there is a specific usecase for such a scenario it can be disabled. Signed-off-by: Alexey Gladkov (Intel) --- arch/x86/coco/tdx/tdx.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c index dfadb085d2d3..5b3421a89998 100644 --- a/arch/x86/coco/tdx/tdx.c +++ b/arch/x86/coco/tdx/tdx.c @@ -411,6 +411,11 @@ static inline bool is_private_gpa(u64 gpa) return gpa == cc_mkenc(gpa); } +static inline bool is_kernel_addr(unsigned long addr) +{ + return (long)addr < 0; +} + static int get_phys_addr(unsigned long addr, phys_addr_t *phys_addr, bool *writable) { unsigned int level; @@ -641,6 +646,7 @@ static int handle_mmio(struct pt_regs *regs, struct ve_info *ve) unsigned long vaddr; int size, ret; + ret = decode_insn_struct(&insn, regs); if (ret) return ret; @@ -661,6 +667,9 @@ static int handle_mmio(struct pt_regs *regs, struct ve_info *ve) ret = valid_vaddr(ve, mmio, size, vaddr); if (ret) goto unlock; + } else if (!is_kernel_addr(ve->gla)) { + WARN_ONCE(1, "Access to userspace address is not supported"); + return -EINVAL; } /* -- 2.45.2