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x86: kvm: avoid -Wsometimes-uninitized warning

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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>
This commit is contained in:
Arnd Bergmann 2019-07-12 16:13:09 +02:00 committed by Paolo Bonzini
parent 0b77462951
commit f4e4805e4b
1 changed files with 9 additions and 11 deletions
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20
arch/x86/kvm/hyperv.c
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@ -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);