Commit f4e4805e authored by Arnd Bergmann's avatar Arnd Bergmann Committed by Paolo Bonzini
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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: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 0b774629

arch/x86/kvm/hyperv.c

+9 −11
Original line number Diff line number Diff line
@@ -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);