[kvm-unit-tests PATCH 0/2] Fix Clang 24 -Wunused-but-set-global warnings

[kvm-unit-tests PATCH 0/2] Fix Clang 24 -Wunused-but-set-global warnings

[Yosry Ahmed]

Building kvm-unit-tests with Clang 24 fails with -Werror due to the new
-Wunused-but-set-global warning flagging static variables that are
written to but never read in lib/chr-testdev.c and lib/x86/desc.c.

Remove both unused variables.

Yosry Ahmed (2):
  chr-testdev: Remove unused in_vq
  x86/desc: Remove unused exception flag

 lib/chr-testdev.c | 3 +--
 lib/x86/desc.c    | 2 --
 2 files changed, 1 insertion(+), 4 deletions(-)


base-commit: 5a221342a025948fa7d84f0c404748f6ba57f3ad
-- 
2.56.0.257.gf7497c7d27-goog

[kvm-unit-tests PATCH 1/2] chr-testdev: Remove unused in_vq

[Yosry Ahmed]

in_vq is assigned in chr_testdev_init() from vqs[0], but kvm-unit-tests
only writes to the character device via out_vq and never consumes input
from the host. Clang 24 warns on this with -Wunused-but-set-global:

  lib/chr-testdev.c:15:26: error: variable 'in_vq' set but not used
  [-Werror,-Wunused-but-set-global]

Remove the unused variable.

Fixes: b412ad0d39a1 ("Introduce chr-testdev")
Co-developed-by: Greg Thelen <gthelen@google.com>
Signed-off-by: Greg Thelen <gthelen@google.com>
Signed-off-by: Yosry Ahmed <yosry@kernel.org>
---
 lib/chr-testdev.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/lib/chr-testdev.c b/lib/chr-testdev.c
index b3c641a833feb..c23fd92a46308 100644
--- a/lib/chr-testdev.c
+++ b/lib/chr-testdev.c
@@ -12,7 +12,7 @@
 #define TESTDEV_NAME "chr-testdev"
 
 static struct virtio_device *vcon;
-static struct virtqueue *in_vq, *out_vq;
+static struct virtqueue *out_vq;
 static struct spinlock lock;
 
 static void __testdev_send(char *buf, unsigned int len)
@@ -65,6 +65,5 @@ void chr_testdev_init(void)
 		return;
 	}
 
-	in_vq = vqs[0];
 	out_vq = vqs[1];
 }
-- 
2.56.0.257.gf7497c7d27-goog

[kvm-unit-tests PATCH 2/2] x86/desc: Remove unused exception flag

[Yosry Ahmed]

exception is set to true in exception_handler() but is never read
because exception recovery redirects regs->rip to
exception_handler_longjmp(). Clang 24 warns on this with
-Wunused-but-set-global:

  lib/x86/desc.c:483:13: error: variable 'exception' set but not used
  [-Werror,-Wunused-but-set-global]

Remove the unused variable.

Fixes: 932ba2d2f530 ("x86: simplify test_for_exception trigger functions")
Co-developed-by: Greg Thelen <gthelen@google.com>
Signed-off-by: Greg Thelen <gthelen@google.com>
Signed-off-by: Yosry Ahmed <yosry@kernel.org>
---
 lib/x86/desc.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/lib/x86/desc.c b/lib/x86/desc.c
index f4cdfbc92c560..b5d4056260a1d 100644
--- a/lib/x86/desc.c
+++ b/lib/x86/desc.c
@@ -480,7 +480,6 @@ void setup_alt_stack(void)
 }
 #endif
 
-static bool exception;
 static jmp_buf *exception_jmpbuf;
 
 static void exception_handler_longjmp(void)
@@ -491,7 +490,6 @@ static void exception_handler_longjmp(void)
 static void exception_handler(struct ex_regs *regs)
 {
 	/* longjmp must happen after iret, so do not do it now.  */
-	exception = true;
 	regs->rip = (unsigned long)&exception_handler_longjmp;
 	regs->cs = read_cs();
 }
-- 
2.56.0.257.gf7497c7d27-goog

Re: [kvm-unit-tests PATCH 1/2] chr-testdev: Remove unused in_vq

[Andrew Jones]

On Thu, Oct 22, 2026 at 08:44:12PM +0000, Yosry Ahmed wrote:
> in_vq is assigned in chr_testdev_init() from vqs[0], but kvm-unit-tests
> only writes to the character device via out_vq and never consumes input
> from the host. Clang 24 warns on this with -Wunused-but-set-global:
> 
>   lib/chr-testdev.c:15:26: error: variable 'in_vq' set but not used
>   [-Werror,-Wunused-but-set-global]
> 
> Remove the unused variable.
> 
> Fixes: b412ad0d39a1 ("Introduce chr-testdev")
> Co-developed-by: Greg Thelen <gthelen@google.com>
> Signed-off-by: Greg Thelen <gthelen@google.com>
> Signed-off-by: Yosry Ahmed <yosry@kernel.org>
> ---
>  lib/chr-testdev.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/lib/chr-testdev.c b/lib/chr-testdev.c
> index b3c641a833feb..c23fd92a46308 100644
> --- a/lib/chr-testdev.c
> +++ b/lib/chr-testdev.c
> @@ -12,7 +12,7 @@
>  #define TESTDEV_NAME "chr-testdev"
>  
>  static struct virtio_device *vcon;
> -static struct virtqueue *in_vq, *out_vq;
> +static struct virtqueue *out_vq;
>  static struct spinlock lock;
>  
>  static void __testdev_send(char *buf, unsigned int len)
> @@ -65,6 +65,5 @@ void chr_testdev_init(void)
>  		return;
>  	}
>  
> -	in_vq = vqs[0];
>  	out_vq = vqs[1];
>  }
> -- 
> 2.56.0.257.gf7497c7d27-goog
>

Reviewed-by: Andrew Jones <andrew.jones@linux.dev>