linux-kernel - [PATCH] x86/cpu/vmware: use the full form of inl in VMWARE

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Message-Id: <20191007192129.104336-1-samitolvanen@google.com>
Date:   Mon,  7 Oct 2019 12:21:29 -0700
From:   Sami Tolvanen <samitolvanen@...gle.com>
To:     Thomas Hellstrom <thellstrom@...are.com>, pv-drivers@...are.com,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>
Cc:     hpa@...or.com, Kees Cook <keescook@...omium.org>, x86@...nel.org,
        virtualization@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, clang-built-linux@...glegroups.com,
        Sami Tolvanen <samitolvanen@...gle.com>
Subject: [PATCH] x86/cpu/vmware: use the full form of inl in VMWARE_PORT

LLVM's assembler doesn't accept the short form inl (%%dx) instruction,
but instead insists on the output register to be explicitly specified:

  <inline asm>:1:7: error: invalid operand for instruction
          inl (%dx)
             ^
  LLVM ERROR: Error parsing inline asm

Use the full form of the instruction to fix the build.

Signed-off-by: Sami Tolvanen <samitolvanen@...gle.com>
---
 arch/x86/kernel/cpu/vmware.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/vmware.c b/arch/x86/kernel/cpu/vmware.c
index 9735139cfdf8..46d732696c1c 100644
--- a/arch/x86/kernel/cpu/vmware.c
+++ b/arch/x86/kernel/cpu/vmware.c
@@ -49,7 +49,7 @@
 #define VMWARE_CMD_VCPU_RESERVED 31
 
 #define VMWARE_PORT(cmd, eax, ebx, ecx, edx)				\
-	__asm__("inl (%%dx)" :						\
+	__asm__("inl (%%dx), %%eax" :					\
 		"=a"(eax), "=c"(ecx), "=d"(edx), "=b"(ebx) :		\
 		"a"(VMWARE_HYPERVISOR_MAGIC),				\
 		"c"(VMWARE_CMD_##cmd),					\
-- 
2.23.0.581.g78d2f28ef7-goog