[libvirt] [PATCH v4 1/3] qemu: hostdev: Move parts of qemuHostdevHostSupportsPassthroughVFIO() into separate function

[Michal Privoznik]

On 06/01/2018 10:15 AM, Filip Alac wrote:
> Signed-off-by: Filip Alac <filipalac at gmail.com>
> ---
>  src/libvirt_private.syms |  1 +
>  src/qemu/qemu_hostdev.c  | 29 ++++-------------------------
>  src/util/virutil.c       | 28 ++++++++++++++++++++++++++++
>  src/util/virutil.h       |  2 ++
>  4 files changed, 35 insertions(+), 25 deletions(-)
> 
> diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
> index 6001635916..dacaf9d94b 100644
> --- a/src/libvirt_private.syms
> +++ b/src/libvirt_private.syms
> @@ -3073,6 +3073,7 @@ virGetUserName;
>  virGetUserRuntimeDirectory;
>  virGetUserShell;
>  virHexToBin;
> +virHostHasIOMMU;
>  virIndexToDiskName;
>  virIsDevMapperDevice;
>  virIsSUID;
> diff --git a/src/qemu/qemu_hostdev.c b/src/qemu/qemu_hostdev.c
> index 955b5df1a3..25e2dcf868 100644
> --- a/src/qemu/qemu_hostdev.c
> +++ b/src/qemu/qemu_hostdev.c
> @@ -23,7 +23,6 @@
>  
>  #include <config.h>
>  
> -#include <dirent.h>
>  #include <fcntl.h>
>  #include <sys/ioctl.h>
>  #include <errno.h>
> @@ -124,33 +123,13 @@ qemuHostdevUpdateActiveDomainDevices(virQEMUDriverPtr driver,
>  bool
>  qemuHostdevHostSupportsPassthroughVFIO(void)
>  {
> -    DIR *iommuDir = NULL;
> -    struct dirent *iommuGroup = NULL;
> -    bool ret = false;
> -    int direrr;
> -
> -    /* condition 1 - /sys/kernel/iommu_groups/ contains entries */

Thos comment should stay in here. I mean, whether host supports VFIO
passthrough depends on two conditions. Removing comments that say does
not increase code readability.

> -    if (virDirOpenQuiet(&iommuDir, "/sys/kernel/iommu_groups/") < 0)
> -        goto cleanup;
> -
> -    while ((direrr = virDirRead(iommuDir, &iommuGroup, NULL)) > 0) {
> -        /* assume we found a group */
> -        break;
> -    }
> -
> -    if (direrr < 0 || !iommuGroup)
> -        goto cleanup;
> -    /* okay, iommu is on and recognizes groups */
> +    if (!virHostHasIOMMU())
> +        return false;
>  
> -    /* condition 2 - /dev/vfio/vfio exists */
>      if (!virFileExists("/dev/vfio/vfio"))
> -        goto cleanup;
> -
> -    ret = true;
> +        return false;
>  
> - cleanup:
> -    VIR_DIR_CLOSE(iommuDir);
> -    return ret;
> +    return true;
>  }
>  
>  
> diff --git a/src/util/virutil.c b/src/util/virutil.c
> index bb4474acd5..7edcda0ee7 100644
> --- a/src/util/virutil.c
> +++ b/src/util/virutil.c
> @@ -2090,3 +2090,31 @@ virMemoryMaxValue(bool capped)
>      else
>          return LLONG_MAX;
>  }
> +

See how other functions are separated by two empty lines? Might be worth
to honour the consistency.

> +bool
> +virHostHasIOMMU(void)
> +{
> +    DIR *iommuDir = NULL;
> +    struct dirent *iommuGroup = NULL;
> +    bool ret = false;
> +    int direrr;
> +
> +    /* condition 1 - /sys/kernel/iommu_groups/ contains entries */

Huh, this comment does not belong here. It doesn't make much sense here.
You need to keep it in the original function.

> +    if (virDirOpenQuiet(&iommuDir, "/sys/kernel/iommu_groups/") < 0)
> +        goto cleanup;
> +
> +    while ((direrr = virDirRead(iommuDir, &iommuGroup, NULL)) > 0) {
> +        /* assume we found a group */
> +        break;
> +    }
> +
> +    if (direrr < 0 || !iommuGroup)
> +        goto cleanup;
> +    /* okay, iommu is on and recognizes groups */
> +
> +    ret = true;
> +
> + cleanup:
> +    VIR_DIR_CLOSE(iommuDir);
> +    return ret;
> +}
> diff --git a/src/util/virutil.h b/src/util/virutil.h
> index be0f6b0ea8..1ba9635bd9 100644
> --- a/src/util/virutil.h
> +++ b/src/util/virutil.h
> @@ -216,6 +216,8 @@ unsigned long long virMemoryLimitTruncate(unsigned long long value);
>  bool virMemoryLimitIsSet(unsigned long long value);
>  unsigned long long virMemoryMaxValue(bool ulong) ATTRIBUTE_NOINLINE;
>  
> +bool virHostHasIOMMU(void);
> +
>  /**
>   * VIR_ASSIGN_IS_OVERFLOW:
>   * @rvalue: value that is checked (evaluated twice)
> 

Michal