From: Arnd Bergmann <arnd@arndb.de>
To: "Paolo Bonzini" <pbonzini@redhat.com>,
"Radim Krčmář" <rkrcmar@redhat.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Ingo Molnar" <mingo@redhat.com>,
"Borislav Petkov" <bp@alien8.de>,
x86@kernel.org
Cc: Arnd Bergmann <arnd@arndb.de>, "H. Peter Anvin" <hpa@zytor.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Roman Kagan <rkagan@virtuozzo.com>,
Liran Alon <liran.alon@oracle.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
clang-built-linux@googlegroups.com
Subject: [PATCH] [v3] x86: kvm: avoid -Wsometimes-uninitized warning
Date: Fri, 12 Jul 2019 16:13:09 +0200 [thread overview]
Message-ID: <20190712141322.1073650-1-arnd@arndb.de> (raw)
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
next reply other threads:[~2019-07-12 14:13 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-12 14:13 Arnd Bergmann [this message]
2019-07-12 16:33 ` [PATCH] [v3] x86: kvm: avoid -Wsometimes-uninitized warning Roman Kagan
2019-07-12 17:44 ` Nathan Chancellor
2019-07-12 17:45 ` Paolo Bonzini
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190712141322.1073650-1-arnd@arndb.de \
--to=arnd@arndb.de \
--cc=bp@alien8.de \
--cc=clang-built-linux@googlegroups.com \
--cc=hpa@zytor.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=liran.alon@oracle.com \
--cc=mingo@redhat.com \
--cc=pbonzini@redhat.com \
--cc=rkagan@virtuozzo.com \
--cc=rkrcmar@redhat.com \
--cc=tglx@linutronix.de \
--cc=vkuznets@redhat.com \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).