Re: [Qemu-devel] [PATCH v3 1/3] s390x/sclp: proper support of larger send and receive masks

[Claudio Imbrenda]

On Fri, 23 Feb 2018 15:27:02 +0100
Christian Borntraeger  wrote:

[...]

> > +/* copy up to dst_len bytes and fill the rest of dst with zeroes
> > */  
> 
> you just moved this function but shouldnt it be
> 
>   src_len bytes and fill will zeroes until dst_len?

true, will fix


[...]

> > @@ -356,6 +369,34 @@ static void command_handler(SCLPEventFacility
> > *ef, SCCB *sccb, uint64_t code) }
> >  }
> > 
> > +static bool vmstate_event_facility_mask_length_needed(void *opaque)
> > +{
> > +SCLPEventFacility *ef = opaque;
> > +
> > +return ef->allow_all_mask_sizes;
> > +}
> > +
> > +static int vmstate_event_facility_mask_length_pre_load(void
> > *opaque) +{
> > +SCLPEventFacility *ef = opaque;
> > +
> > +ef->allow_all_mask_sizes = false;
> > +return 0;
> > +}  
> 
> why do we need this? Shouldnt the value be set solely by the machine
> version?

will fix

> > +
> > +static const VMStateDescription vmstate_event_facility_mask_length
> > = {
> > +.name = "vmstate-event-facility/mask_length",
> > +.version_id = 0,
> > +.minimum_version_id = 0,
> > +.needed = vmstate_event_facility_mask_length_needed,
> > +.pre_load = vmstate_event_facility_mask_length_pre_load,
> > +.fields = (VMStateField[]) {
> > +VMSTATE_BOOL(allow_all_mask_sizes, SCLPEventFacility),  
> 
> same here. Do we really need to migrate "allow_all_mask_sizes" ?
> Shouldnt that only depend on machine <= 2.11?

will fix

> > +VMSTATE_UINT16(mask_length, SCLPEventFacility),
> > +VMSTATE_END_OF_LIST()
> > + }
> > +};
> > +
> >  static const VMStateDescription vmstate_event_facility = {
> >  .name = "vmstate-event-facility",
> >  .version_id = 0,
> > @@ -363,15 +404,39 @@ static const VMStateDescription
> > vmstate_event_facility = { .fields = (VMStateField[]) {
> >  VMSTATE_UINT32(receive_mask, SCLPEventFacility),
> >  VMSTATE_END_OF_LIST()
> > + },
> > +.subsections = (const VMStateDescription * []) {
> > +_event_facility_mask_length,
> > +NULL
> >   }
> >  };
> > 
> > +static void sclp_event_set_allow_all_mask_sizes(Object *obj, bool
> > value,
> > +   Error
> > **errp) +{
> > +SCLPEventFacility *ef = (SCLPEventFacility *)obj;
> > +
> > +ef->allow_all_mask_sizes = value;
> > +}
> > +
> > +static bool sclp_event_get_allow_all_mask_sizes(Object *obj, Error
> > **e) +{
> > +SCLPEventFacility *ef = (SCLPEventFacility *)obj;
> > +
> > +return ef->allow_all_mask_sizes;
> > +}
> > +
> >  static void init_event_facility(Object *obj)
> >  {
> >  SCLPEventFacility *event_facility = EVENT_FACILITY(obj);
> >  DeviceState *sdev = DEVICE(obj);
> >  Object *new;
> > 
> > +event_facility->mask_length = 4;
> > +event_facility->allow_all_mask_sizes = true;
> > +object_property_add_bool(obj, "allow_all_mask_sizes",
> > + sclp_event_get_allow_all_mask_sizes,
> > + sclp_event_set_allow_all_mask_sizes,
> > NULL); /* Spawn a new bus for SCLP events */
> >  qbus_create_inplace(_facility->sbus,
> > sizeof(event_facility->sbus), TYPE_SCLP_EVENTS_BUS, sdev, NULL);
> > diff --git a/hw/s390x/s390-virtio-ccw.c b/hw/s390x/s390-virtio-ccw.c
> > index 8b3053f..e9309fd 100644
> > --- a/hw/s390x/s390-virtio-ccw.c
> > +++ b/hw/s390x/s390-virtio-ccw.c
> > @@ -29,6 +29,7 @@
> >  #include "s390-pci-bus.h"
> >  #include "hw/s390x/storage-keys.h"
> >  #include "hw/s390x/storage-attributes.h"
> > +#include "hw/s390x/event-facility.h"
> >  #include "hw/compat.h"
> >  #include "ipl.h"
> >  #include "hw/s390x/s390-virtio-ccw.h"
> > @@ -671,7 +672,12 @@ bool css_migration_enabled(void)
> >  type_init(ccw_machine_register_##suffix)
> > 
> >  #define CCW_COMPAT_2_11 \
> > -HW_COMPAT_2_11
> > +HW_COMPAT_2_11 \
> > +{\
> > +.driver   = TYPE_SCLP_EVENT_FACILITY,\
> > +.property = "allow_all_mask_sizes",\
> > +.value= "off",\
> > +},
> > 
> >  #define CCW_COMPAT_2_10 \
> >  HW_COMPAT_2_10
> >   
> 
> Otherwise looks good.

Re: [Qemu-devel] [PATCH v3 1/3] s390x/sclp: proper support of larger send and receive masks

[Christian Borntraeger]

On 02/23/2018 01:51 PM, Claudio Imbrenda wrote:
> Until 67915de9f0383ccf4a ("s390x/event-facility: variable-length event masks")
> we only supported sclp event masks with a size of exactly 4 bytes, even
> though the architecture allows the guests to set up sclp event masks
> from 1 to 1021 bytes in length.
> After that patch, the behaviour was almost compliant, but some issues
> were still remaining, in particular regarding the handling of selective
> reads and migration.
> 
> When setting the sclp event mask, a mask size is also specified. Until
> now we only considered the size in order to decide which bits to save
> in the internal state. On the other hand, when a guest performs a
> selective read, it sends a mask, but it does not specify a size; the
> implied size is the size of the last mask that has been set.
> 
> Specifying bits in the mask of selective read that are not available in
> the internal mask should return an error, and bits past the end of the
> mask should obviously be ignored. This can only be achieved by keeping
> track of the lenght of the mask.
> 
> The mask length is thus now part of the internal state that needs to be
> migrated.
> 
> This patch fixes the handling of selective reads, whose size will now
> match the length of the event mask, as per architecture.
> 
> While the default behaviour is to be compliant with the architecture,
> when using older machine models the old broken behaviour is selected
> (allowing only masks of size exactly 4), in order to be able to migrate
> toward older versions.
> 
> Fixes: 67915de9f0383ccf4a ("s390x/event-facility: variable-length event 
> masks")
> Signed-off-by: Claudio Imbrenda 
> ---
>  hw/s390x/event-facility.c  | 91 
> +++---
>  hw/s390x/s390-virtio-ccw.c |  8 +++-
>  2 files changed, 85 insertions(+), 14 deletions(-)
> 
> diff --git a/hw/s390x/event-facility.c b/hw/s390x/event-facility.c
> index 155a694..b7cd075 100644
> --- a/hw/s390x/event-facility.c
> +++ b/hw/s390x/event-facility.c
> @@ -31,6 +31,15 @@ struct SCLPEventFacility {
>  SCLPEventsBus sbus;
>  /* guest' receive mask */
>  unsigned int receive_mask;
> +/*
> + * when false, we keep the same broken, backwards compatible behaviour as
> + * before, allowing only masks of size exactly 4; when true, we implement
> + * the architecture correctly, allowing all valid mask sizes. Needed for
> + * migration toward older versions.
> + */
> +bool allow_all_mask_sizes;
> +/* length of the receive mask */
> +uint16_t mask_length;
>  };
> 
>  /* return true if any child has event pending set */
> @@ -220,6 +229,17 @@ static uint16_t 
> handle_sccb_read_events(SCLPEventFacility *ef, SCCB *sccb,
>  return rc;
>  }
> 
> +/* copy up to dst_len bytes and fill the rest of dst with zeroes */

you just moved this function but shouldnt it be

src_len bytes and fill will zeroes until dst_len?

> +static void copy_mask(uint8_t *dst, uint8_t *src, uint16_t dst_len,
> +  uint16_t src_len)
> +{
> +int i;
> +
> +for (i = 0; i < dst_len; i++) {
> +dst[i] = i < src_len ? src[i] : 0;
> +}
> +}
> +
>  static void read_event_data(SCLPEventFacility *ef, SCCB *sccb)
>  {
>  unsigned int sclp_active_selection_mask;
> @@ -240,7 +260,9 @@ static void read_event_data(SCLPEventFacility *ef, SCCB 
> *sccb)
>  sclp_active_selection_mask = sclp_cp_receive_mask;
>  break;
>  case SCLP_SELECTIVE_READ:
> -sclp_active_selection_mask = be32_to_cpu(red->mask);
> +copy_mask((uint8_t *)_active_selection_mask, (uint8_t 
> *)>mask,
> +  sizeof(sclp_active_selection_mask), ef->mask_length);
> +sclp_active_selection_mask = be32_to_cpu(sclp_active_selection_mask);
>  if (!sclp_cp_receive_mask ||
>  (sclp_active_selection_mask & ~sclp_cp_receive_mask)) {
>  sccb->h.response_code =
> @@ -259,24 +281,14 @@ out:
>  return;
>  }
> 
> -/* copy up to dst_len bytes and fill the rest of dst with zeroes */
> -static void copy_mask(uint8_t *dst, uint8_t *src, uint16_t dst_len,
> -  uint16_t src_len)
> -{
> -int i;
> -
> -for (i = 0; i < dst_len; i++) {
> -dst[i] = i < src_len ? src[i] : 0;
> -}
> -}
> -
>  static void write_event_mask(SCLPEventFacility *ef, SCCB *sccb)
>  {
>  WriteEventMask *we_mask = (WriteEventMask *) sccb;
>  uint16_t mask_length = be16_to_cpu(we_mask->mask_length);
>  uint32_t tmp_mask;
> 
> -if (!mask_length || (mask_length > SCLP_EVENT_MASK_LEN_MAX)) {
> +if (!mask_length || (mask_length > SCLP_EVENT_MASK_LEN_MAX) ||
> +((mask_length != 4) && !ef->allow_all_mask_sizes)) {
>  sccb->h.response_code = cpu_to_be16(SCLP_RC_INVALID_MASK_LENGTH);
>  goto out;
>  }
> @@ -301,6 +313,7 @@ static void write_event_mask(SCLPEventFacility *ef, SCCB 
> *sccb)
>