[libvirt] [PATCH 2/2] conf: Move VFIO AP validation from post parse to QEMU validation code

[Boris Fiuczynski]

On 11/12/18 1:14 PM, Erik Skultety wrote:
> Even though commit 11708641 claims that a domain is allowed have a
> single VFIO AP hostdev only, this is a limitation posed by the platform
> vendor on purely virtual devices. Generally, post parse should only be
I am little confused by the term "purely virtual devices".
If you are talking about the mediated device itself "purely virtual" 
sounds okay but if you also consider what it represents within a guest 
than that is no longer "purely virtual" since a vfio-ap hostdev 
represents a bunch of "real crypto hardware" that is passed through to 
the guest.

> used to populate some default values if missing or at least fail
> gracefully with VIR_DOMAIN_DEF_PARSE_ALLOW_POST_PARSE_FAIL).
> 
> This patch more of an attempt to follow the guidelines for adding new
> features rather than a precaution measure, since even if vfio-ap
> supported multiple devices, one would have to downgrade libvirt for a
> machine to vanish from the list or in terms of future device migration
> to slightly older libvirt, there would be most probably a driver mismatch
> that would render the migration impossible anyway.

I agree that this is the correct place for the checking. Thanks for 
catching and fixing it. I successfully ran some tests with these changes 
with regard to vfio-ap. Looks good to me so far.

> 
> Signed-off-by: Erik Skultety <eskultet at redhat.com>
> ---
>   src/conf/domain_conf.c | 28 ----------------------------
>   src/qemu/qemu_domain.c | 28 +++++++++++++++++++++++++++-
>   2 files changed, 27 insertions(+), 29 deletions(-)
> 
> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
> index 237540bccc..e8e0adc819 100644
> --- a/src/conf/domain_conf.c
> +++ b/src/conf/domain_conf.c
> @@ -4275,31 +4275,6 @@ virDomainDefPostParseGraphics(virDomainDef *def)
>   }
>   
>   
> -static int
> -virDomainDefPostParseHostdev(virDomainDefPtr def)
> -{
> -    size_t i;
> -    bool vfioap_found = false;
> -
> -    /* verify settings of hostdevs vfio-ap */
> -    for (i = 0; i < def->nhostdevs; i++) {
> -        virDomainHostdevDefPtr hostdev = def->hostdevs[i];
> -
> -        if (virHostdevIsMdevDevice(hostdev) &&
> -            hostdev->source.subsys.u.mdev.model == VIR_MDEV_MODEL_TYPE_VFIO_AP) {
> -            if (vfioap_found) {
> -                virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
> -                               _("Only one hostdev of model vfio-ap is "
> -                                 "supported"));
> -                return -1;
> -            }
> -            vfioap_found = true;
> -        }
> -    }
> -    return 0;
> -}
> -
> -
>   /**
>    * virDomainDriveAddressIsUsedByDisk:
>    * @def: domain definition containing the disks to check
> @@ -5210,9 +5185,6 @@ virDomainDefPostParseCommon(virDomainDefPtr def,
>   
>       virDomainDefPostParseGraphics(def);
>   
> -    if (virDomainDefPostParseHostdev(def) < 0)
> -        return -1;
> -
>       if (virDomainDefPostParseCPU(def) < 0)
>           return -1;
>   
> diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
> index 17d207513d..90253ae867 100644
> --- a/src/qemu/qemu_domain.c
> +++ b/src/qemu/qemu_domain.c
> @@ -4599,6 +4599,32 @@ qemuDomainMdevDefVFIOPCIValidate(const virDomainHostdevSubsysMediatedDev *dev,
>   }
>   
>   
> +static int
> +qemuDomainMdevDefVFIOAPValidate(const virDomainDef *def)
> +{
> +    size_t i;
> +    bool vfioap_found = false;
> +
> +    /* currently, VFIO-AP is restricted to a single device only */
Well, even so it is just on mdev device it defines the complete set of 
crypto devices consisting of adapters, domains and controldomains on the 
AP bus of the guest. The ap architecture allows only one such 
configuration.
So I suggest to remove "currently," and instead of "single device" to 
write "single mediated device".

Besides that
Reviewed-by: Boris Fiuczynski <fiuczy at linux.ibm.com>


> +    for (i = 0; i < def->nhostdevs; i++) {
> +        virDomainHostdevDefPtr hostdev = def->hostdevs[i];
> +
> +        if (virHostdevIsMdevDevice(hostdev) &&
> +            hostdev->source.subsys.u.mdev.model == VIR_MDEV_MODEL_TYPE_VFIO_AP) {
> +            if (vfioap_found) {
> +                virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
> +                               _("Only one hostdev of model vfio-ap is "
> +                                 "supported"));
> +                return -1;
> +            }
> +            vfioap_found = true;
> +        }
> +    }
> +
> +    return 0;
> +}
> +
> +
>   static int
>   qemuDomainMdevDefValidate(const virDomainHostdevSubsysMediatedDev *mdevsrc,
>                             const virDomainDef *def,
> @@ -4609,7 +4635,7 @@ qemuDomainMdevDefValidate(const virDomainHostdevSubsysMediatedDev *mdevsrc,
>       case VIR_MDEV_MODEL_TYPE_VFIO_PCI:
>           return qemuDomainMdevDefVFIOPCIValidate(mdevsrc, def, qemuCaps);
>       case VIR_MDEV_MODEL_TYPE_VFIO_AP:
> -        break;
> +        return qemuDomainMdevDefVFIOAPValidate(def);
>       case VIR_MDEV_MODEL_TYPE_VFIO_CCW:
>           break;
>       case VIR_MDEV_MODEL_TYPE_LAST:
> 


-- 
Mit freundlichen Grüßen/Kind regards
    Boris Fiuczynski

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