linux-kernel - [PATCH v3 05/10] x86/tdx: Avoid crossing the page boundary

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Message-ID: <b6281bb223a69ae082d0f31c531ef991e0a077ee.1723807851.git.legion@kernel.org>
Date: Fri, 16 Aug 2024 15:43:55 +0200
From: Alexey Gladkov <legion@...nel.org>
To: linux-kernel@...r.kernel.org,
	linux-coco@...ts.linux.dev
Cc: "Alexey Gladkov (Intel)" <legion@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Yuan Yao <yuan.yao@...el.com>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Yuntao Wang <ytcoode@...il.com>,
	Kai Huang <kai.huang@...el.com>,
	Baoquan He <bhe@...hat.com>,
	Oleg Nesterov <oleg@...hat.com>,
	cho@...rosoft.com,
	decui@...rosoft.com,
	John.Starks@...rosoft.com
Subject: [PATCH v3 05/10] x86/tdx: Avoid crossing the page boundary

From: "Alexey Gladkov (Intel)" <legion@...nel.org>

Try to avoid crossing the page boundary to avoid side effects if the
next page belongs to another VMA.

Signed-off-by: Alexey Gladkov (Intel) <legion@...nel.org>
---
 arch/x86/coco/tdx/tdx.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c
index 254d5293d25a..e3d692342603 100644
--- a/arch/x86/coco/tdx/tdx.c
+++ b/arch/x86/coco/tdx/tdx.c
@@ -489,13 +489,10 @@ static int decode_insn_struct(struct insn *insn, struct pt_regs *regs)
 	char buffer[MAX_INSN_SIZE];
 
 	if (user_mode(regs)) {
-		int nr_copied = insn_fetch_from_user(regs, buffer);
+		int ret = insn_fetch_decode_from_user(insn, regs);
 
-		if (nr_copied <= 0)
-			return -EFAULT;
-
-		if (!insn_decode_from_regs(insn, regs, buffer, nr_copied))
-			return -EINVAL;
+		if (ret)
+			return ret;
 	} else {
 		if (copy_from_kernel_nofault(buffer, (void *)regs->ip, MAX_INSN_SIZE))
 			return -EFAULT;
-- 
2.45.2