Re: [PATCH v2 1/1] hw/s390x: modularize virtio-gpu-ccw

[Boris Fiuczynski <fiuczy@linux.ibm.com>]

Paolo, Daniel,
I am in general (s390 unrelated) a bit puzzled about the scenario of 
QEMU being modularized.
Libvirt probes QEMU executables for their capabilities and creates a 
capabilities cache of the probed QEMU binary. There are a few triggers 
that invalidate the cache. One is the QEMU binary changing.
Is there one for QEMU modules being installed or uninstalled?
How is that supposed to work?


On 2/22/21 1:55 PM, Halil Pasic wrote:
> Since the virtio-gpu-ccw device depends on the hw-display-virtio-gpu
> module, which provides the type virtio-gpu-device, packaging the
> hw-display-virtio-gpu module as a separate package that may or may not
> be installed along with the qemu package leads to problems. Namely if
> the hw-display-virtio-gpu is absent, qemu continues to advertise
> virtio-gpu-ccw, but it aborts not only when one attempts using
> virtio-gpu-ccw, but also when libvirtd's capability probing tries
> to instantiate the type to introspect it.
> 
> Let us thus introduce a module named hw-s390x-virtio-gpu-ccw that
> is going to provide the virtio-gpu-ccw device. The hw-s390x prefix
> was chosen because it is not a portable device.
> 
> With virtio-gpu-ccw built as a module, the correct way to package a
> modularized qemu is to require that hw-display-virtio-gpu must be
> installed whenever the module hw-s390x-virtio-gpu-ccw.
> 
> The definition S390_ADAPTER_SUPPRESSIBLE was moved to "cpu.h", per
> suggestion of Thomas Huth. From interface design perspective, IMHO, not
> a good thing as it belongs to the public interface of
> css_register_io_adapters(). We did this because CONFIG_KVM requeires
> NEED_CPU_H and Thomas, and other commenters did not like the
> consequences of that.
> 
> Moving the interrupt related declarations to s390_flic.h was suggested
> by Cornelia Huck.
> 
> Introducing type_register_mayfail() was suggested by Gerd Hoffmann.
> 
> Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
> ---
>   hw/s390x/meson.build         |  7 +++++-
>   hw/s390x/virtio-ccw-gpu.c    |  4 ++++
>   include/hw/s390x/css.h       |  7 ------
>   include/hw/s390x/s390_flic.h |  3 +++
>   include/qom/object.h         | 22 +++++++++++++++++++
>   qom/object.c                 | 42 ++++++++++++++++++++++++------------
>   target/s390x/cpu.h           |  9 +++++---
>   util/module.c                |  1 +
>   8 files changed, 70 insertions(+), 25 deletions(-)
> 
> diff --git a/hw/s390x/meson.build b/hw/s390x/meson.build
> index 2a7818d94b..7ac972afcf 100644
> --- a/hw/s390x/meson.build
> +++ b/hw/s390x/meson.build
> @@ -34,7 +34,6 @@ virtio_ss.add(files('virtio-ccw.c'))
>   virtio_ss.add(when: 'CONFIG_VIRTIO_BALLOON', if_true: files('virtio-ccw-balloon.c'))
>   virtio_ss.add(when: 'CONFIG_VIRTIO_BLK', if_true: files('virtio-ccw-blk.c'))
>   virtio_ss.add(when: 'CONFIG_VIRTIO_CRYPTO', if_true: files('virtio-ccw-crypto.c'))
> -virtio_ss.add(when: 'CONFIG_VIRTIO_GPU', if_true: files('virtio-ccw-gpu.c'))
>   virtio_ss.add(when: 'CONFIG_VIRTIO_INPUT', if_true: files('virtio-ccw-input.c'))
>   virtio_ss.add(when: 'CONFIG_VIRTIO_NET', if_true: files('virtio-ccw-net.c'))
>   virtio_ss.add(when: 'CONFIG_VIRTIO_RNG', if_true: files('virtio-ccw-rng.c'))
> @@ -46,3 +45,9 @@ virtio_ss.add(when: 'CONFIG_VHOST_USER_FS', if_true: files('vhost-user-fs-ccw.c'
>   s390x_ss.add_all(when: 'CONFIG_VIRTIO_CCW', if_true: virtio_ss)
>   
>   hw_arch += {'s390x': s390x_ss}
> +
> +hw_s390x_modules = {}
> +virtio_gpu_ccw_ss = ss.source_set()
> +virtio_gpu_ccw_ss.add(when: 'CONFIG_VIRTIO_GPU', if_true: [files('virtio-ccw-gpu.c'), pixman])
> +hw_s390x_modules += {'virtio-gpu-ccw': virtio_gpu_ccw_ss}
> +modules += {'hw-s390x': hw_s390x_modules}
> diff --git a/hw/s390x/virtio-ccw-gpu.c b/hw/s390x/virtio-ccw-gpu.c
> index c301e2586b..5ac9b6b2a6 100644
> --- a/hw/s390x/virtio-ccw-gpu.c
> +++ b/hw/s390x/virtio-ccw-gpu.c
> @@ -62,7 +62,11 @@ static const TypeInfo virtio_ccw_gpu = {
>   
>   static void virtio_ccw_gpu_register(void)
>   {
> +#ifdef CONFIG_MODULES
> +    type_register_static_mayfail(&virtio_ccw_gpu);
> +#else
>       type_register_static(&virtio_ccw_gpu);
> +#endif
>   }
>   
>   type_init(virtio_ccw_gpu_register)
> diff --git a/include/hw/s390x/css.h b/include/hw/s390x/css.h
> index 08c869ab0a..7858666307 100644
> --- a/include/hw/s390x/css.h
> +++ b/include/hw/s390x/css.h
> @@ -12,7 +12,6 @@
>   #ifndef CSS_H
>   #define CSS_H
>   
> -#include "cpu.h"
>   #include "hw/s390x/adapter.h"
>   #include "hw/s390x/s390_flic.h"
>   #include "hw/s390x/ioinst.h"
> @@ -233,12 +232,6 @@ uint32_t css_get_adapter_id(CssIoAdapterType type, uint8_t isc);
>   void css_register_io_adapters(CssIoAdapterType type, bool swap, bool maskable,
>                                 uint8_t flags, Error **errp);
>   
> -#ifndef CONFIG_KVM
> -#define S390_ADAPTER_SUPPRESSIBLE 0x01
> -#else
> -#define S390_ADAPTER_SUPPRESSIBLE KVM_S390_ADAPTER_SUPPRESSIBLE
> -#endif
> -
>   #ifndef CONFIG_USER_ONLY
>   SubchDev *css_find_subch(uint8_t m, uint8_t cssid, uint8_t ssid,
>                            uint16_t schid);
> diff --git a/include/hw/s390x/s390_flic.h b/include/hw/s390x/s390_flic.h
> index e91b15d2d6..3907a13d07 100644
> --- a/include/hw/s390x/s390_flic.h
> +++ b/include/hw/s390x/s390_flic.h
> @@ -134,6 +134,9 @@ void s390_flic_init(void);
>   S390FLICState *s390_get_flic(void);
>   QEMUS390FLICState *s390_get_qemu_flic(S390FLICState *fs);
>   S390FLICStateClass *s390_get_flic_class(S390FLICState *fs);
> +void s390_crw_mchk(void);
> +void s390_io_interrupt(uint16_t subchannel_id, uint16_t subchannel_nr,
> +                       uint32_t io_int_parm, uint32_t io_int_word);
>   bool ais_needed(void *opaque);
>   
>   #endif /* HW_S390_FLIC_H */
> diff --git a/include/qom/object.h b/include/qom/object.h
> index 6721cd312e..3428546d91 100644
> --- a/include/qom/object.h
> +++ b/include/qom/object.h
> @@ -826,6 +826,17 @@ const char *object_get_typename(const Object *obj);
>    */
>   Type type_register_static(const TypeInfo *info);
>   
> +/**
> + * type_register_static_mayfail:
> + * @info: The #TypeInfo of the new type.
> + *
> + * @info and all of the strings it points to should exist for the life time
> + * that the type is registered.
> + *
> + * Returns: the new #Type or NULL if missing a parent type.
> + */
> +Type type_register_static_mayfail(const TypeInfo *info);
> +
>   /**
>    * type_register:
>    * @info: The #TypeInfo of the new type
> @@ -837,6 +848,17 @@ Type type_register_static(const TypeInfo *info);
>    */
>   Type type_register(const TypeInfo *info);
>   
> +/**
> + * type_register_mayfail:
> + * @info: The #TypeInfo of the new type
> + *
> + * Unlike type_register_static(), this call does not require @info or its
> + * string members to continue to exist after the call returns.
> + *
> + * Returns: the new #Type or NULL if missing a parent type.
> + */
> +Type type_register_mayfail(const TypeInfo *info);
> +
>   /**
>    * type_register_static_array:
>    * @infos: The array of the new type #TypeInfo structures.
> diff --git a/qom/object.c b/qom/object.c
> index 491823db4a..ed217cbfb0 100644
> --- a/qom/object.c
> +++ b/qom/object.c
> @@ -135,7 +135,7 @@ static TypeImpl *type_new(const TypeInfo *info)
>       return ti;
>   }
>   
> -static TypeImpl *type_register_internal(const TypeInfo *info)
> +static TypeImpl *type_register_internal(const TypeInfo *info, bool mayfail)
>   {
>       TypeImpl *ti;
>       ti = type_new(info);
> @@ -147,7 +147,13 @@ static TypeImpl *type_register_internal(const TypeInfo *info)
>   TypeImpl *type_register(const TypeInfo *info)
>   {
>       assert(info->parent);
> -    return type_register_internal(info);
> +    return type_register_internal(info, false);
> +}
> +
> +TypeImpl *type_register_mayfail(const TypeInfo *info)
> +{
> +    assert(info->parent);
> +    return type_register_internal(info, true);
>   }
>   
>   TypeImpl *type_register_static(const TypeInfo *info)
> @@ -155,6 +161,11 @@ TypeImpl *type_register_static(const TypeInfo *info)
>       return type_register(info);
>   }
>   
> +TypeImpl *type_register_static_mayfail(const TypeInfo *info)
> +{
> +    return type_register_mayfail(info);
> +}
> +
>   void type_register_static_array(const TypeInfo *infos, int nr_infos)
>   {
>       int i;
> @@ -173,13 +184,16 @@ static TypeImpl *type_get_by_name(const char *name)
>       return type_table_lookup(name);
>   }
>   
> -static TypeImpl *type_get_parent(TypeImpl *type)
> +static TypeImpl *type_get_parent(TypeImpl *type, bool mayfail)
>   {
>       if (!type->parent_type && type->parent) {
>           type->parent_type = type_get_by_name(type->parent);
>           if (!type->parent_type) {
>               fprintf(stderr, "Type '%s' is missing its parent '%s'\n",
>                       type->name, type->parent);
> +            if (mayfail) {
> +                return NULL;
> +            }
>               abort();
>           }
>       }
> @@ -199,7 +213,7 @@ static size_t type_class_get_size(TypeImpl *ti)
>       }
>   
>       if (type_has_parent(ti)) {
> -        return type_class_get_size(type_get_parent(ti));
> +        return type_class_get_size(type_get_parent(ti, false));
>       }
>   
>       return sizeof(ObjectClass);
> @@ -212,7 +226,7 @@ static size_t type_object_get_size(TypeImpl *ti)
>       }
>   
>       if (type_has_parent(ti)) {
> -        return type_object_get_size(type_get_parent(ti));
> +        return type_object_get_size(type_get_parent(ti, false));
>       }
>   
>       return 0;
> @@ -236,7 +250,7 @@ static bool type_is_ancestor(TypeImpl *type, TypeImpl *target_type)
>               return true;
>           }
>   
> -        type = type_get_parent(type);
> +        type = type_get_parent(type, false);
>       }
>   
>       return false;
> @@ -307,7 +321,7 @@ static void type_initialize(TypeImpl *ti)
>       }
>       ti->class = g_malloc0(ti->class_size);
>   
> -    parent = type_get_parent(ti);
> +    parent = type_get_parent(ti, false);
>       if (parent) {
>           type_initialize(parent);
>           GSList *e;
> @@ -357,7 +371,7 @@ static void type_initialize(TypeImpl *ti)
>           if (parent->class_base_init) {
>               parent->class_base_init(ti->class, ti->class_data);
>           }
> -        parent = type_get_parent(parent);
> +        parent = type_get_parent(parent, false);
>       }
>   
>       if (ti->class_init) {
> @@ -368,7 +382,7 @@ static void type_initialize(TypeImpl *ti)
>   static void object_init_with_type(Object *obj, TypeImpl *ti)
>   {
>       if (type_has_parent(ti)) {
> -        object_init_with_type(obj, type_get_parent(ti));
> +        object_init_with_type(obj, type_get_parent(ti, false));
>       }
>   
>       if (ti->instance_init) {
> @@ -383,7 +397,7 @@ static void object_post_init_with_type(Object *obj, TypeImpl *ti)
>       }
>   
>       if (type_has_parent(ti)) {
> -        object_post_init_with_type(obj, type_get_parent(ti));
> +        object_post_init_with_type(obj, type_get_parent(ti, false));
>       }
>   }
>   
> @@ -674,7 +688,7 @@ static void object_deinit(Object *obj, TypeImpl *type)
>       }
>   
>       if (type_has_parent(type)) {
> -        object_deinit(obj, type_get_parent(type));
> +        object_deinit(obj, type_get_parent(type, false));
>       }
>   }
>   
> @@ -1040,7 +1054,7 @@ ObjectClass *module_object_class_by_name(const char *typename)
>   
>   ObjectClass *object_class_get_parent(ObjectClass *class)
>   {
> -    TypeImpl *type = type_get_parent(class->type);
> +    TypeImpl *type = type_get_parent(class->type, false);
>   
>       if (!type) {
>           return NULL;
> @@ -2791,8 +2805,8 @@ static void register_types(void)
>           .abstract = true,
>       };
>   
> -    type_interface = type_register_internal(&interface_info);
> -    type_register_internal(&object_info);
> +    type_interface = type_register_internal(&interface_info, false);
> +    type_register_internal(&object_info, false);
>   }
>   
>   type_init(register_types)
> diff --git a/target/s390x/cpu.h b/target/s390x/cpu.h
> index 60d434d5ed..b434b905c0 100644
> --- a/target/s390x/cpu.h
> +++ b/target/s390x/cpu.h
> @@ -40,6 +40,12 @@
>   
>   #define S390_MAX_CPUS 248
>   
> +#ifndef CONFIG_KVM
> +#define S390_ADAPTER_SUPPRESSIBLE 0x01
> +#else
> +#define S390_ADAPTER_SUPPRESSIBLE KVM_S390_ADAPTER_SUPPRESSIBLE
> +#endif
> +
>   typedef struct PSW {
>       uint64_t mask;
>       uint64_t addr;
> @@ -806,9 +812,6 @@ int cpu_s390x_signal_handler(int host_signum, void *pinfo, void *puc);
>   
>   
>   /* interrupt.c */
> -void s390_crw_mchk(void);
> -void s390_io_interrupt(uint16_t subchannel_id, uint16_t subchannel_nr,
> -                       uint32_t io_int_parm, uint32_t io_int_word);
>   #define RA_IGNORED                  0
>   void s390_program_interrupt(CPUS390XState *env, uint32_t code, uintptr_t ra);
>   /* service interrupts are floating therefore we must not pass an cpustate */
> diff --git a/util/module.c b/util/module.c
> index c65060c167..cbe89fede6 100644
> --- a/util/module.c
> +++ b/util/module.c
> @@ -304,6 +304,7 @@ static struct {
>       { "virtio-gpu-pci-base",   "hw-", "display-virtio-gpu-pci" },
>       { "virtio-gpu-pci",        "hw-", "display-virtio-gpu-pci" },
>       { "vhost-user-gpu-pci",    "hw-", "display-virtio-gpu-pci" },
> +    { "virtio-gpu-ccw",        "hw-", "s390x-virtio-gpu-ccw"   },
>       { "virtio-vga-base",       "hw-", "display-virtio-vga"    },
>       { "virtio-vga",            "hw-", "display-virtio-vga"    },
>       { "vhost-user-vga",        "hw-", "display-virtio-vga"    },
> 
> base-commit: 1af5629673bb5c1592d993f9fb6119a62845f576
> 


-- 
Mit freundlichen Grüßen/Kind regards
    Boris Fiuczynski

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