[1/2] s390: Add a hypercall registration interface.

Allow virtio machines to register for different diag500 function
codes and convert s390-virtio to use it.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
---
 hw/s390-virtio.c             | 94 ++++++++++++++++++++++++--------------------
 hw/s390-virtio.h             | 23 +++++++++++
 hw/s390x/Makefile.objs       |  1 +
 hw/s390x/s390-virtio-hcall.c | 33 ++++++++++++++++
 target-s390x/cpu.h           |  2 +-
 target-s390x/kvm.c           |  2 +-
 target-s390x/misc_helper.c   |  2 +-
 7 files changed, 112 insertions(+), 45 deletions(-)
 create mode 100644 hw/s390-virtio.h
 create mode 100644 hw/s390x/s390-virtio-hcall.c

On 16.01.2013, at 12:57, Cornelia Huck wrote:

> Allow virtio machines to register for different diag500 function
> codes and convert s390-virtio to use it.
> 
> Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>

Nice cleanup :). One minor nitpick below

> ---
> hw/s390-virtio.c             | 94 ++++++++++++++++++++++++--------------------
> hw/s390-virtio.h             | 23 +++++++++++
> hw/s390x/Makefile.objs       |  1 +
> hw/s390x/s390-virtio-hcall.c | 33 ++++++++++++++++
> target-s390x/cpu.h           |  2 +-
> target-s390x/kvm.c           |  2 +-
> target-s390x/misc_helper.c   |  2 +-
> 7 files changed, 112 insertions(+), 45 deletions(-)
> create mode 100644 hw/s390-virtio.h
> create mode 100644 hw/s390x/s390-virtio-hcall.c
> 
> diff --git a/hw/s390-virtio.c b/hw/s390-virtio.c
> index 0e93cc3..91ad43b 100644
> --- a/hw/s390-virtio.c
> +++ b/hw/s390-virtio.c
> @@ -33,6 +33,7 @@
> 
> #include "hw/s390-virtio-bus.h"
> #include "hw/s390x/sclp.h"
> +#include "hw/s390-virtio.h"
> 
> //#define DEBUG_S390
> 
> @@ -44,10 +45,6 @@
>     do { } while (0)
> #endif
> 
> -#define KVM_S390_VIRTIO_NOTIFY          0
> -#define KVM_S390_VIRTIO_RESET           1
> -#define KVM_S390_VIRTIO_SET_STATUS      2
> -
> #define KERN_IMAGE_START                0x010000UL
> #define KERN_PARM_AREA                  0x010480UL
> #define INITRD_START                    0x800000UL
> @@ -73,56 +70,67 @@ S390CPU *s390_cpu_addr2state(uint16_t cpu_addr)
>     return ipi_states[cpu_addr];
> }
> 
> -int s390_virtio_hypercall(CPUS390XState *env, uint64_t mem, uint64_t hypercall)
> +static int s390_virtio_hcall_notify(uint64_t reg2, uint64_t reg3, uint64_t reg4,
> +                                    uint64_t reg5, uint64_t reg6, uint64_t reg7)
> {
> +    uint64_t mem = reg2;
>     int r = 0, i;
> 
> -    dprintf("KVM hypercall: %ld\n", hypercall);
> -    switch (hypercall) {
> -    case KVM_S390_VIRTIO_NOTIFY:
> -        if (mem > ram_size) {
> -            VirtIOS390Device *dev = s390_virtio_bus_find_vring(s390_bus,
> -                                                               mem, &i);
> -            if (dev) {
> -                virtio_queue_notify(dev->vdev, i);
> -            } else {
> -                r = -EINVAL;
> -            }
> -        } else {
> -            /* Early printk */
> -        }
> -        break;
> -    case KVM_S390_VIRTIO_RESET:
> -    {
> -        VirtIOS390Device *dev;
> -
> -        dev = s390_virtio_bus_find_mem(s390_bus, mem);
> -        virtio_reset(dev->vdev);
> -        stb_phys(dev->dev_offs + VIRTIO_DEV_OFFS_STATUS, 0);
> -        s390_virtio_device_sync(dev);
> -        s390_virtio_reset_idx(dev);
> -        break;
> -    }
> -    case KVM_S390_VIRTIO_SET_STATUS:
> -    {
> -        VirtIOS390Device *dev;
> -
> -        dev = s390_virtio_bus_find_mem(s390_bus, mem);
> +    if (mem > ram_size) {
> +        VirtIOS390Device *dev = s390_virtio_bus_find_vring(s390_bus, mem, &i);
>         if (dev) {
> -            s390_virtio_device_update_status(dev);
> +            virtio_queue_notify(dev->vdev, i);
>         } else {
>             r = -EINVAL;
>         }
> -        break;
> +    } else {
> +        /* Early printk */
>     }
> -    default:
> +    return r;
> +}
> +
> +static int s390_virtio_hcall_reset(uint64_t reg2, uint64_t reg3, uint64_t reg4,
> +                                   uint64_t reg5, uint64_t reg6, uint64_t reg7)
> +{
> +    uint64_t mem = reg2;
> +    VirtIOS390Device *dev;
> +
> +    dev = s390_virtio_bus_find_mem(s390_bus, mem);
> +    virtio_reset(dev->vdev);
> +    stb_phys(dev->dev_offs + VIRTIO_DEV_OFFS_STATUS, 0);
> +    s390_virtio_device_sync(dev);
> +    s390_virtio_reset_idx(dev);
> +
> +    return 0;
> +}
> +
> +static int s390_virtio_hcall_set_status(uint64_t reg2, uint64_t reg3,
> +                                        uint64_t reg4, uint64_t reg5,
> +                                        uint64_t reg6, uint64_t reg7)
> +{
> +    uint64_t mem = reg2;
> +    int r = 0;
> +    VirtIOS390Device *dev;
> +
> +    dev = s390_virtio_bus_find_mem(s390_bus, mem);
> +    if (dev) {
> +        s390_virtio_device_update_status(dev);
> +    } else {
>         r = -EINVAL;
> -        break;
>     }
> -
>     return r;
> }
> 
> +static void s390_virtio_register_hcalls(void)
> +{
> +    s390_register_virtio_hypercall(KVM_S390_VIRTIO_NOTIFY,
> +                                   s390_virtio_hcall_notify);
> +    s390_register_virtio_hypercall(KVM_S390_VIRTIO_RESET,
> +                                   s390_virtio_hcall_reset);
> +    s390_register_virtio_hypercall(KVM_S390_VIRTIO_SET_STATUS,
> +                                   s390_virtio_hcall_set_status);
> +}
> +
> /*
>  * The number of running CPUs. On s390 a shutdown is the state of all CPUs
>  * being either stopped or disabled (for interrupts) waiting. We have to
> @@ -186,6 +194,9 @@ static void s390_init(QEMUMachineInitArgs *args)
>     s390_bus = s390_virtio_bus_init(&my_ram_size);
>     s390_sclp_init();
> 
> +    /* register hypercalls */
> +    s390_virtio_register_hcalls();
> +
>     /* allocate RAM */
>     memory_region_init_ram(ram, "s390.ram", my_ram_size);
>     vmstate_register_ram_global(ram);
> @@ -339,4 +350,3 @@ static void s390_machine_init(void)
> }
> 
> machine_init(s390_machine_init);
> -
> diff --git a/hw/s390-virtio.h b/hw/s390-virtio.h
> new file mode 100644
> index 0000000..cd88179
> --- /dev/null
> +++ b/hw/s390-virtio.h
> @@ -0,0 +1,23 @@
> +/*
> + * Virtio interfaces for s390
> + *
> + * Copyright 2012 IBM Corp.
> + * Author(s): Cornelia Huck <cornelia.huck@de.ibm.com>
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or (at
> + * your option) any later version. See the COPYING file in the top-level
> + * directory.
> + */
> +
> +#ifndef HW_S390_VIRTIO_H
> +#define HW_S390_VIRTIO_H 1
> +
> +#define KVM_S390_VIRTIO_NOTIFY          0
> +#define KVM_S390_VIRTIO_RESET           1
> +#define KVM_S390_VIRTIO_SET_STATUS      2
> +
> +typedef int (*s390_virtio_fn)(uint64_t reg2, uint64_t reg3, uint64_t reg4,
> +                              uint64_t reg5, uint64_t reg6, uint64_t reg7);

const uint64_t *args

> +void s390_register_virtio_hypercall(uint64_t code, s390_virtio_fn fn);
> +
> +#endif
> diff --git a/hw/s390x/Makefile.objs b/hw/s390x/Makefile.objs
> index 096dfcd..ae87a12 100644
> --- a/hw/s390x/Makefile.objs
> +++ b/hw/s390x/Makefile.objs
> @@ -1,6 +1,7 @@
> obj-y = s390-virtio-bus.o s390-virtio.o
> 
> obj-y := $(addprefix ../,$(obj-y))
> +obj-y += s390-virtio-hcall.o
> obj-y += sclp.o
> obj-y += event-facility.o
> obj-y += sclpquiesce.o sclpconsole.o
> diff --git a/hw/s390x/s390-virtio-hcall.c b/hw/s390x/s390-virtio-hcall.c
> new file mode 100644
> index 0000000..cc5f47f
> --- /dev/null
> +++ b/hw/s390x/s390-virtio-hcall.c
> @@ -0,0 +1,33 @@
> +/*
> + * Support for virtio hypercalls on s390
> + *
> + * Copyright 2012 IBM Corp.
> + * Author(s): Cornelia Huck <cornelia.huck@de.ibm.com>
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or (at
> + * your option) any later version. See the COPYING file in the top-level
> + * directory.
> + */
> +
> +#include "cpu.h"
> +#include "hw/s390-virtio.h"
> +
> +#define MAX_DIAG_SUBCODES 255
> +
> +static s390_virtio_fn s390_diag500_table[MAX_DIAG_SUBCODES];
> +
> +void s390_register_virtio_hypercall(uint64_t code, s390_virtio_fn fn)
> +{
> +    assert(code < MAX_DIAG_SUBCODES);
> +    assert(!s390_diag500_table[code]);
> +
> +    s390_diag500_table[code] = fn;
> +}
> +
> +int s390_virtio_hypercall(CPUS390XState *env)
> +{
> +    s390_virtio_fn fn = s390_diag500_table[env->regs[1]];
> +
> +    return fn ? fn(env->regs[2], env->regs[3], env->regs[4], env->regs[5],
> +                   env->regs[6], env->regs[7]) : -EINVAL;

if (!fn) {
    return -EINVAL;
}

return fn(&env->regs[2]);

That way the hypercall handling function can determine itself which registers it really needs to access.


> +}
> diff --git a/target-s390x/cpu.h b/target-s390x/cpu.h
> index bc3fab2..6700fe9 100644
> --- a/target-s390x/cpu.h
> +++ b/target-s390x/cpu.h
> @@ -302,7 +302,7 @@ int cpu_s390x_handle_mmu_fault (CPUS390XState *env, target_ulong address, int rw
> void s390x_tod_timer(void *opaque);
> void s390x_cpu_timer(void *opaque);
> 
> -int s390_virtio_hypercall(CPUS390XState *env, uint64_t mem, uint64_t hypercall);
> +int s390_virtio_hypercall(CPUS390XState *env);
> 
> #ifdef CONFIG_KVM
> void kvm_s390_interrupt(S390CPU *cpu, int type, uint32_t code);
> diff --git a/target-s390x/kvm.c b/target-s390x/kvm.c
> index 6ec5e6d..ae6ae07 100644
> --- a/target-s390x/kvm.c
> +++ b/target-s390x/kvm.c
> @@ -386,7 +386,7 @@ static int handle_priv(S390CPU *cpu, struct kvm_run *run, uint8_t ipa1)
> static int handle_hypercall(CPUS390XState *env, struct kvm_run *run)
> {
>     cpu_synchronize_state(env);
> -    env->regs[2] = s390_virtio_hypercall(env, env->regs[2], env->regs[1]);
> +    env->regs[2] = s390_virtio_hypercall(env);

Just thinking out loud here. With synchronized registers, we have full access to the GPRs already without copying them to env. So if instead we would call

    s390_virtio_hypercall(env->regs);

we could in case we support synchronized registers call

    s390_virtio_hypercall(kvm_run->s.regs.gprs);

which would completely remove the need for cpu_synchronize_state() for normal hypercalls.

This is outside of the scope of this patch, but might be a useful thing to do :). As a nice side effect, the global s390_virtio_hypercall function wouldn't have to know anything about CPUState either.


Alex

On Wed, 16 Jan 2013 13:17:34 +0100
Alexander Graf <agraf@suse.de> wrote:

> 
> On 16.01.2013, at 12:57, Cornelia Huck wrote:
> 
> > Allow virtio machines to register for different diag500 function
> > codes and convert s390-virtio to use it.
> > 
> > Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
> 
> Nice cleanup :). One minor nitpick below

> > +int s390_virtio_hypercall(CPUS390XState *env)
> > +{
> > +    s390_virtio_fn fn = s390_diag500_table[env->regs[1]];
> > +
> > +    return fn ? fn(env->regs[2], env->regs[3], env->regs[4], env->regs[5],
> > +                   env->regs[6], env->regs[7]) : -EINVAL;
> 
> if (!fn) {
>     return -EINVAL;
> }
> 
> return fn(&env->regs[2]);
> 
> That way the hypercall handling function can determine itself which registers it really needs to access.

Yes, this looks a bit nicer. v2 is on the way.

> 
> 
> > +}

> > static int handle_hypercall(CPUS390XState *env, struct kvm_run *run)
> > {
> >     cpu_synchronize_state(env);
> > -    env->regs[2] = s390_virtio_hypercall(env, env->regs[2], env->regs[1]);
> > +    env->regs[2] = s390_virtio_hypercall(env);
> 
> Just thinking out loud here. With synchronized registers, we have full access to the GPRs already without copying them to env. So if instead we would call
> 
>     s390_virtio_hypercall(env->regs);
> 
> we could in case we support synchronized registers call
> 
>     s390_virtio_hypercall(kvm_run->s.regs.gprs);
> 
> which would completely remove the need for cpu_synchronize_state() for normal hypercalls.
> 
> This is outside of the scope of this patch, but might be a useful thing to do :). As a nice side effect, the global s390_virtio_hypercall function wouldn't have to know anything about CPUState either.

Sounds like a good future improvement.