* [PATCH] [v3] x86: kvm: avoid -Wsometimes-uninitized warning
@ 2019-07-12 14:13 Arnd Bergmann
2019-07-12 16:33 ` Roman Kagan
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: Arnd Bergmann @ 2019-07-12 14:13 UTC (permalink / raw)
To: Paolo Bonzini, Radim Krčmář,
Thomas Gleixner, Ingo Molnar, Borislav Petkov, x86
Cc: Arnd Bergmann, H. Peter Anvin, Vitaly Kuznetsov, Roman Kagan,
Liran Alon, kvm, linux-kernel, clang-built-linux
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>
---
v3: reword commit log, simplify patch again
v2: make the change inside of is_64_bit_mode().
---
arch/x86/kvm/hyperv.c | 20 +++++++++-----------
1 file changed, 9 insertions(+), 11 deletions(-)
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index a39e38f13029..c10a8b10b203 100644
--- 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);
--
2.20.0
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] [v3] x86: kvm: avoid -Wsometimes-uninitized warning
2019-07-12 14:13 [PATCH] [v3] x86: kvm: avoid -Wsometimes-uninitized warning Arnd Bergmann
@ 2019-07-12 16:33 ` Roman Kagan
2019-07-12 17:44 ` Nathan Chancellor
2019-07-12 17:45 ` Paolo Bonzini
2 siblings, 0 replies; 4+ messages in thread
From: Roman Kagan @ 2019-07-12 16:33 UTC (permalink / raw)
To: Arnd Bergmann
Cc: Paolo Bonzini, Radim Krčmář,
Thomas Gleixner, Ingo Molnar, Borislav Petkov, x86,
H. Peter Anvin, Vitaly Kuznetsov, Liran Alon, kvm, linux-kernel,
clang-built-linux
On Fri, Jul 12, 2019 at 04:13:09PM +0200, Arnd Bergmann wrote:
> 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>
> ---
> v3: reword commit log, simplify patch again
> v2: make the change inside of is_64_bit_mode().
> ---
> arch/x86/kvm/hyperv.c | 20 +++++++++-----------
> 1 file changed, 9 insertions(+), 11 deletions(-)
Reviewed-by: Roman Kagan <rkagan@virtuozzo.com>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] [v3] x86: kvm: avoid -Wsometimes-uninitized warning
2019-07-12 14:13 [PATCH] [v3] x86: kvm: avoid -Wsometimes-uninitized warning Arnd Bergmann
2019-07-12 16:33 ` Roman Kagan
@ 2019-07-12 17:44 ` Nathan Chancellor
2019-07-12 17:45 ` Paolo Bonzini
2 siblings, 0 replies; 4+ messages in thread
From: Nathan Chancellor @ 2019-07-12 17:44 UTC (permalink / raw)
To: Arnd Bergmann
Cc: Paolo Bonzini, Radim Krčmář,
Thomas Gleixner, Ingo Molnar, Borislav Petkov, x86,
H. Peter Anvin, Vitaly Kuznetsov, Roman Kagan, Liran Alon, kvm,
linux-kernel, clang-built-linux
On Fri, Jul 12, 2019 at 04:13:09PM +0200, Arnd Bergmann wrote:
> 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>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] [v3] x86: kvm: avoid -Wsometimes-uninitized warning
2019-07-12 14:13 [PATCH] [v3] x86: kvm: avoid -Wsometimes-uninitized warning Arnd Bergmann
2019-07-12 16:33 ` Roman Kagan
2019-07-12 17:44 ` Nathan Chancellor
@ 2019-07-12 17:45 ` Paolo Bonzini
2 siblings, 0 replies; 4+ messages in thread
From: Paolo Bonzini @ 2019-07-12 17:45 UTC (permalink / raw)
To: Arnd Bergmann, Radim Krčmář,
Thomas Gleixner, Ingo Molnar, Borislav Petkov, x86
Cc: H. Peter Anvin, Vitaly Kuznetsov, Roman Kagan, Liran Alon, kvm,
linux-kernel, clang-built-linux
On 12/07/19 16:13, Arnd Bergmann wrote:
> 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>
> ---
> v3: reword commit log, simplify patch again
> v2: make the change inside of is_64_bit_mode().
> ---
> arch/x86/kvm/hyperv.c | 20 +++++++++-----------
> 1 file changed, 9 insertions(+), 11 deletions(-)
>
> diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
> index a39e38f13029..c10a8b10b203 100644
> --- 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);
>
Queued, thanks.
Paolo
^ permalink raw reply [flat|nested] 4+ messages in thread
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2019-07-12 14:13 [PATCH] [v3] x86: kvm: avoid -Wsometimes-uninitized warning Arnd Bergmann
2019-07-12 16:33 ` Roman Kagan
2019-07-12 17:44 ` Nathan Chancellor
2019-07-12 17:45 ` Paolo Bonzini
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