x86: kvm: avoid -Wsometimes-uninitized warning

Clang notices a code path in which some variables are never
initialized, but fails to figure out that this can never happen
on i386 because is_64_bit_mode() always returns false.

arch/x86/kvm/hyperv.c:1610:6: error: variable 'ingpa' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
        if (!longmode) {
            ^~~~~~~~~
arch/x86/kvm/hyperv.c:1632:55: note: uninitialized use occurs here
        trace_kvm_hv_hypercall(code, fast, rep_cnt, rep_idx, ingpa, outgpa);
                                                             ^~~~~
arch/x86/kvm/hyperv.c:1610:2: note: remove the 'if' if its condition is always true
        if (!longmode) {
        ^~~~~~~~~~~~~~~
arch/x86/kvm/hyperv.c:1595:18: note: initialize the variable 'ingpa' to silence this warning
        u64 param, ingpa, outgpa, ret = HV_STATUS_SUCCESS;
                        ^
                         = 0
arch/x86/kvm/hyperv.c:1610:6: error: variable 'outgpa' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
arch/x86/kvm/hyperv.c:1610:6: error: variable 'param' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]

Flip the condition around to avoid the conditional execution on i386.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index a39e38f13029164246f5b4a9136dd6cb6e2a6229..c10a8b10b203b706ce2b84b28e45fa0042bb1d77 100644 (file)
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -1594,7 +1594,7 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
 {
        u64 param, ingpa, outgpa, ret = HV_STATUS_SUCCESS;
        uint16_t code, rep_idx, rep_cnt;
-       bool fast, longmode, rep;
+       bool fast, rep;
 
        /*
         * hypercall generates UD from non zero cpl and real mode
@@ -1605,9 +1605,14 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
                return 1;
        }
 
-       longmode = is_64_bit_mode(vcpu);
-
-       if (!longmode) {
+#ifdef CONFIG_X86_64
+       if (is_64_bit_mode(vcpu)) {
+               param = kvm_rcx_read(vcpu);
+               ingpa = kvm_rdx_read(vcpu);
+               outgpa = kvm_r8_read(vcpu);
+       } else
+#endif
+       {
                param = ((u64)kvm_rdx_read(vcpu) << 32) |
                        (kvm_rax_read(vcpu) & 0xffffffff);
                ingpa = ((u64)kvm_rbx_read(vcpu) << 32) |
@@ -1615,13 +1620,6 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
                outgpa = ((u64)kvm_rdi_read(vcpu) << 32) |
                        (kvm_rsi_read(vcpu) & 0xffffffff);
        }
-#ifdef CONFIG_X86_64
-       else {
-               param = kvm_rcx_read(vcpu);
-               ingpa = kvm_rdx_read(vcpu);
-               outgpa = kvm_r8_read(vcpu);
-       }
-#endif
 
        code = param & 0xffff;
        fast = !!(param & HV_HYPERCALL_FAST_BIT);