2022-03-22 19:22:53

by Nathan Chancellor

Subject: [PATCH] KVM: x86: Fix clang -Wimplicit-fallthrough in do_host_cpuid()

Clang warns:

arch/x86/kvm/cpuid.c:739:2: error: unannotated fall-through between switch labels [-Werror,-Wimplicit-fallthrough]
default:
^
arch/x86/kvm/cpuid.c:739:2: note: insert 'break;' to avoid fall-through
default:
^
break;
1 error generated.

Clang is a little more pedantic than GCC, which does not warn when
falling through to a case that is just break or return. Clang's version
is more in line with the kernel's own stance in deprecated.rst, which
states that all switch/case blocks must end in either break,
fallthrough, continue, goto, or return. Add the missing break to silence
the warning.

Fixes: f144c49e8c39 ("KVM: x86: synthesize CPUID leaf 0x80000021h if useful")
Reported-by: kernel test robot <[email protected]>
Signed-off-by: Nathan Chancellor <[email protected]>
---
arch/x86/kvm/cpuid.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 58b0b4e0263c..a3c87d2882ad 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -735,6 +735,7 @@ static struct kvm_cpuid_entry2 *do_host_cpuid(struct kvm_cpuid_array *array,
if (function > READ_ONCE(max_cpuid_80000000))
return entry;
}
+ break;

default:
break;

base-commit: c9b8fecddb5bb4b67e351bbaeaa648a6f7456912
--
2.35.1

2022-03-25 18:17:19

by Paolo Bonzini

Subject: Re: [PATCH] KVM: x86: Fix clang -Wimplicit-fallthrough in do_host_cpuid()

Queued, thanks.

Paolo