Re: [PATCH 1/2] kvm tools: Add kvm__has_cap() to check whether a cap is available on the host

[Matt Evans <matt@ozlabs.org>]

On 14/12/11 17:37, Sasha Levin wrote:
> Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
> ---
>  tools/kvm/include/kvm/kvm.h |    2 ++
>  tools/kvm/kvm.c             |    5 +++++
>  2 files changed, 7 insertions(+), 0 deletions(-)
> 
> diff --git a/tools/kvm/include/kvm/kvm.h b/tools/kvm/include/kvm/kvm.h
> index 7159952..d24b70a 100644
> --- a/tools/kvm/include/kvm/kvm.h
> +++ b/tools/kvm/include/kvm/kvm.h
> @@ -79,4 +79,6 @@ static inline void *guest_flat_to_host(struct kvm *kvm, unsigned long offset)
>  	return kvm->ram_start + offset;
>  }
>  
> +bool kvm__has_cap(struct kvm *kvm, u32 cap);
> +
>  #endif /* KVM__KVM_H */
> diff --git a/tools/kvm/kvm.c b/tools/kvm/kvm.c
> index 35ca2c5..a2f7a89 100644
> --- a/tools/kvm/kvm.c
> +++ b/tools/kvm/kvm.c
> @@ -517,3 +517,8 @@ void kvm__notify_paused(void)
>  	mutex_lock(&pause_lock);
>  	mutex_unlock(&pause_lock);
>  }
> +
> +bool kvm__has_cap(struct kvm *kvm, u32 cap)
> +{
> +	return ioctl(kvm->sys_fd, KVM_CHECK_EXTENSION, cap) == 0;
> +}
                                                            ^^^^

D'oh, this needs to be != 0, not == 0.


Cheers,


Matt

---

From: Matt Evans <matt@ozlabs.org>
Date: Thu, 15 Dec 2011 15:19:47 +1100
Subject: [PATCH] kvm tools: Fix inverted logic bug in kvm__has_cap

Commit 42efb1abf4ebebeedd14af34c073e673923e2898 compared KVM_CHECK_EXTENSION's
result wrong, stating 'has cap' true if 0.  Invert the comparison.

Signed-off-by: Matt Evans <matt@ozlabs.org>
---
 tools/kvm/kvm.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/tools/kvm/kvm.c b/tools/kvm/kvm.c
index 9583ab2..25f1419 100644
--- a/tools/kvm/kvm.c
+++ b/tools/kvm/kvm.c
@@ -523,5 +523,5 @@ void kvm__notify_paused(void)
 
 bool kvm__has_cap(struct kvm *kvm, u32 cap)
 {
-	return ioctl(kvm->sys_fd, KVM_CHECK_EXTENSION, cap) == 0;
+	return ioctl(kvm->sys_fd, KVM_CHECK_EXTENSION, cap) != 0;
 }
-- 
1.7.0.4