linux-kernel - [PATCH] x86/sev: Fix operator precedence in GHCB_MSR_VMPL_REQ

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Message-Id: <20250510162726.90681-1-cloudlee1719@gmail.com>
Date: Sun, 11 May 2025 01:27:24 +0900
From: Seongmanlee <cloudlee1719@...il.com>
To: x86@...nel.org
Cc: leonardo-leecaprio <augustus92@...st.ac.kr>,
	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>,
	linux-kernel@...r.kernel.org (open list:X86 ARCHITECTURE (32-BIT AND 64-BIT))
Subject: [PATCH] x86/sev: Fix operator precedence in GHCB_MSR_VMPL_REQ_LEVEL macro

From: leonardo-leecaprio <augustus92@...st.ac.kr>

The GHCB_MSR_VMPL_REQ_LEVEL macro lacked parentheses around the bitmask
expression, causing the shift operation to bind too early. As a result,
when switching to VMPL2 from VMPL1 (e.g., GHCB_MSR_VMPL_REQ_LEVEL(1)),
incorrect values such as 0x000000016 were generated instead of the intended
0x100000016.

This patch fixes the precedence issue by grouping the masked value
before applying the shift.

Signed-off-by: leonardo-leecaprio <augustus92@...st.ac.kr>
---
 arch/x86/include/asm/sev-common.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h
index acb85b934..0020d77a0 100644
--- a/arch/x86/include/asm/sev-common.h
+++ b/arch/x86/include/asm/sev-common.h
@@ -116,7 +116,7 @@ enum psc_op {
 #define GHCB_MSR_VMPL_REQ		0x016
 #define GHCB_MSR_VMPL_REQ_LEVEL(v)			\
 	/* GHCBData[39:32] */				\
-	(((u64)(v) & GENMASK_ULL(7, 0) << 32) |		\
+	((((u64)(v) & GENMASK_ULL(7, 0)) << 32) |	\
 	/* GHCBDdata[11:0] */				\
 	GHCB_MSR_VMPL_REQ)
 
-- 
2.39.5 (Apple Git-154)