From 3dc548051be33059fd29e90662944a606235acbf Mon Sep 17 00:00:00 2001
From: Alexander Potapenko <glider@google.com>
Date: Mon, 8 Oct 2018 10:53:24 +0200
Subject: [PATCH] kmsan: suppress false positives in KVM

KMSAN doesn't see writes from inline asm directives and considers some
locals uninitialized.
---
 arch/x86/include/asm/msr.h |  3 ++-
 arch/x86/kvm/vmx.c         | 15 ++++++++++-----
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/arch/x86/include/asm/msr.h b/arch/x86/include/asm/msr.h
index 04addd6e0a4a2..c09a277d28423 100644
--- a/arch/x86/include/asm/msr.h
+++ b/arch/x86/include/asm/msr.h
@@ -124,7 +124,8 @@ do {							\
 
 static inline unsigned long long native_read_msr(unsigned int msr)
 {
-	unsigned long long val;
+	// TODO(glider): suppressing a false positive.
+	unsigned long long val = 0;
 
 	val = __rdmsr(msr);
 
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index e665aa7167cf9..362da1ccb94bf 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2084,7 +2084,8 @@ static inline void __invvpid(int ext, u16 vpid, gva_t gva)
 	u64 rsvd : 48;
 	u64 gva;
     } operand = { vpid, 0, gva };
-    bool error;
+    // TODO(glider): suppressing a false positive.
+    bool error = false;
 
     asm volatile (__ex(ASM_VMX_INVVPID) CC_SET(na)
 		  : CC_OUT(na) (error) : "a"(&operand), "c"(ext)
@@ -2097,7 +2098,8 @@ static inline void __invept(int ext, u64 eptp, gpa_t gpa)
 	struct {
 		u64 eptp, gpa;
 	} operand = {eptp, gpa};
-	bool error;
+	// TODO(glider): suppressing a false positive.
+	bool error = false;
 
 	asm volatile (__ex(ASM_VMX_INVEPT) CC_SET(na)
 		      : CC_OUT(na) (error) : "a" (&operand), "c" (ext)
@@ -2118,7 +2120,8 @@ static struct shared_msr_entry *find_msr_entry(struct vcpu_vmx *vmx, u32 msr)
 static void vmcs_clear(struct vmcs *vmcs)
 {
 	u64 phys_addr = __pa(vmcs);
-	bool error;
+	// TODO(glider): suppressing a false positive.
+	bool error = false;
 
 	asm volatile (__ex(ASM_VMX_VMCLEAR_RAX) CC_SET(na)
 		      : CC_OUT(na) (error) : "a"(&phys_addr), "m"(phys_addr)
@@ -2140,7 +2143,8 @@ static inline void loaded_vmcs_init(struct loaded_vmcs *loaded_vmcs)
 static void vmcs_load(struct vmcs *vmcs)
 {
 	u64 phys_addr = __pa(vmcs);
-	bool error;
+	// TODO(glider): suppressing a false positive.
+	bool error = false;
 
 	if (static_branch_unlikely(&enable_evmcs))
 		return evmcs_load(phys_addr);
@@ -2373,7 +2377,8 @@ static noinline void vmwrite_error(unsigned long field, unsigned long value)
 
 static __always_inline void __vmcs_writel(unsigned long field, unsigned long value)
 {
-	bool error;
+	// TODO(glider): suppressing a false positive.
+	bool error = false;
 
 	asm volatile (__ex(ASM_VMX_VMWRITE_RAX_RDX) CC_SET(na)
 		      : CC_OUT(na) (error) : "a"(value), "d"(field));