Re: [PATCH] vfio/type1: Initialize resv_msi_base

[Cornelia Huck]

On Tue, 15 Oct 2019 17:16:50 +0200
Joerg Roedel <joro@xxxxxxxxxx> wrote:

> From: Joerg Roedel <jroedel@xxxxxxx>
> 
> After enabling CONFIG_IOMMU_DMA on X86 a new warning appears when
> compiling vfio:
> 
> drivers/vfio/vfio_iommu_type1.c: In function âvfio_iommu_type1_attach_groupâ:
> drivers/vfio/vfio_iommu_type1.c:1827:7: warning: âresv_msi_baseâ may be used uninitialized in this function [-Wmaybe-uninitialized]
>    ret = iommu_get_msi_cookie(domain->domain, resv_msi_base);
>    ~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> The warning is a false positive, because the call to iommu_get_msi_cookie()
> only happens when vfio_iommu_has_sw_msi() returned true. And that only
> happens when it also set resv_msi_base.
> 
> But initialize the variable anyway to get rid of the warning.
> 
> Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>
> ---
>  drivers/vfio/vfio_iommu_type1.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index 96fddc1dafc3..d864277ea16f 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -1658,7 +1658,7 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
>  	struct bus_type *bus = NULL;
>  	int ret;
>  	bool resv_msi, msi_remap;
> -	phys_addr_t resv_msi_base;
> +	phys_addr_t resv_msi_base = 0;
>  	struct iommu_domain_geometry geo;
>  	LIST_HEAD(iova_copy);
>  	LIST_HEAD(group_resv_regions);

Reviewed-by: Cornelia Huck <cohuck@xxxxxxxxxx>