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[Qemu-devel] [PATCH RFC] s390/css: handle CCW_FLAG_SKIP

Cornelia Huck posted 1 patch 4 years, 11 months ago
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git fetch https://github.com/patchew-project/qemu tags/patchew/20190506171730.17556-1-cohuck@redhat.com
Maintainers: David Hildenbrand <david@redhat.com>, Cornelia Huck <cohuck@redhat.com>, Halil Pasic <pasic@linux.ibm.com>, Christian Borntraeger <borntraeger@de.ibm.com>, Richard Henderson <rth@twiddle.net>
There is a newer version of this series
hw/s390x/css.c         | 22 ++++++++++++++++++----
include/hw/s390x/css.h |  1 +
2 files changed, 19 insertions(+), 4 deletions(-)
[Qemu-devel] [PATCH RFC] s390/css: handle CCW_FLAG_SKIP
Posted by Cornelia Huck 4 years, 11 months ago 
If a ccw has CCW_FLAG_SKIP set, and the command is of type
read, read backwards, or sense, no data should be written
to the guest for that command.

Signed-off-by: Cornelia Huck <cohuck@redhat.com>
---

Only extremely lightly tested (i.e., can boot a guest.)

---
 hw/s390x/css.c         | 22 ++++++++++++++++++----
 include/hw/s390x/css.h |  1 +
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/hw/s390x/css.c b/hw/s390x/css.c
index 8fc9e35ba5d3..6ee31cc2e08f 100644
--- a/hw/s390x/css.c
+++ b/hw/s390x/css.c
@@ -830,8 +830,12 @@ static int ccw_dstream_rw_noflags(CcwDataStream *cds, void *buff, int len,
     if (op == CDS_OP_A) {
         goto incr;
     }
-    ret = address_space_rw(&address_space_memory, cds->cda,
-                           MEMTXATTRS_UNSPECIFIED, buff, len, op);
+    if (!cds->do_skip) {
+        ret = address_space_rw(&address_space_memory, cds->cda,
+                               MEMTXATTRS_UNSPECIFIED, buff, len, op);
+    } else {
+        ret = 0;
+    }
     if (ret != MEMTX_OK) {
         cds->flags |= CDS_F_STREAM_BROKEN;
         return -EINVAL;
@@ -928,8 +932,13 @@ static int ccw_dstream_rw_ida(CcwDataStream *cds, void *buff, int len,
     do {
         iter_len = MIN(len, cont_left);
         if (op != CDS_OP_A) {
-            ret = address_space_rw(&address_space_memory, cds->cda,
-                                   MEMTXATTRS_UNSPECIFIED, buff, iter_len, op);
+            if (!cds->do_skip) {
+                ret = address_space_rw(&address_space_memory, cds->cda,
+                                       MEMTXATTRS_UNSPECIFIED, buff, iter_len,
+                                       op);
+            } else {
+                ret = 0;
+            }
             if (ret != MEMTX_OK) {
                 /* assume inaccessible address */
                 ret = -EINVAL; /* channel program check */
@@ -968,6 +977,11 @@ void ccw_dstream_init(CcwDataStream *cds, CCW1 const *ccw, ORB const *orb)
 
     cds->count = ccw->count;
     cds->cda_orig = ccw->cda;
+    /* skip is only effective for read, read backwards, or sense commands */
+    cds->do_skip = (ccw->flags & CCW_FLAG_SKIP) &&
+        (ccw->cmd_code & CCW_CMD_BASIC_SENSE ||
+         ccw->cmd_code & 0x02 /* read */ ||
+         ccw->cmd_code & 0x0c /* read backwards */);
     ccw_dstream_rewind(cds);
     if (!(cds->flags & CDS_F_IDA)) {
         cds->op_handler = ccw_dstream_rw_noflags;
diff --git a/include/hw/s390x/css.h b/include/hw/s390x/css.h
index aae19c427229..7cc183ef4366 100644
--- a/include/hw/s390x/css.h
+++ b/include/hw/s390x/css.h
@@ -97,6 +97,7 @@ typedef struct CcwDataStream {
     int (*op_handler)(struct CcwDataStream *cds, void *buff, int len,
                       CcwDataStreamOp op);
     hwaddr cda;
+    bool do_skip;
 } CcwDataStream;
 
 /*
-- 
2.20.1
Re: [Qemu-devel] [PATCH RFC] s390/css: handle CCW_FLAG_SKIP
Posted by Eric Farman 4 years, 11 months ago 

On 5/6/19 1:17 PM, Cornelia Huck wrote:
> If a ccw has CCW_FLAG_SKIP set, and the command is of type
> read, read backwards, or sense, no data should be written
> to the guest for that command.
> 
> Signed-off-by: Cornelia Huck <cohuck@redhat.com>
> ---
> 
> Only extremely lightly tested (i.e., can boot a guest.)
> 
> ---
>   hw/s390x/css.c         | 22 ++++++++++++++++++----
>   include/hw/s390x/css.h |  1 +
>   2 files changed, 19 insertions(+), 4 deletions(-)
> 
> diff --git a/hw/s390x/css.c b/hw/s390x/css.c
> index 8fc9e35ba5d3..6ee31cc2e08f 100644
> --- a/hw/s390x/css.c
> +++ b/hw/s390x/css.c
> @@ -830,8 +830,12 @@ static int ccw_dstream_rw_noflags(CcwDataStream *cds, void *buff, int len,
>       if (op == CDS_OP_A) {
>           goto incr;
>       }
> -    ret = address_space_rw(&address_space_memory, cds->cda,
> -                           MEMTXATTRS_UNSPECIFIED, buff, len, op);
> +    if (!cds->do_skip) {
> +        ret = address_space_rw(&address_space_memory, cds->cda,
> +                               MEMTXATTRS_UNSPECIFIED, buff, len, op);
> +    } else {
> +        ret = 0;
> +    }
>       if (ret != MEMTX_OK) {
>           cds->flags |= CDS_F_STREAM_BROKEN;
>           return -EINVAL;
> @@ -928,8 +932,13 @@ static int ccw_dstream_rw_ida(CcwDataStream *cds, void *buff, int len,
>       do {
>           iter_len = MIN(len, cont_left);
>           if (op != CDS_OP_A) {
> -            ret = address_space_rw(&address_space_memory, cds->cda,
> -                                   MEMTXATTRS_UNSPECIFIED, buff, iter_len, op);
> +            if (!cds->do_skip) {
> +                ret = address_space_rw(&address_space_memory, cds->cda,
> +                                       MEMTXATTRS_UNSPECIFIED, buff, iter_len,
> +                                       op);
> +            } else {
> +                ret = 0;
> +            }
>               if (ret != MEMTX_OK) {
>                   /* assume inaccessible address */
>                   ret = -EINVAL; /* channel program check */
> @@ -968,6 +977,11 @@ void ccw_dstream_init(CcwDataStream *cds, CCW1 const *ccw, ORB const *orb)
>   
>       cds->count = ccw->count;
>       cds->cda_orig = ccw->cda;
> +    /* skip is only effective for read, read backwards, or sense commands */
> +    cds->do_skip = (ccw->flags & CCW_FLAG_SKIP) &&
> +        (ccw->cmd_code & CCW_CMD_BASIC_SENSE ||
> +         ccw->cmd_code & 0x02 /* read */ ||
> +         ccw->cmd_code & 0x0c /* read backwards */);

I wish so badly that these checks work, since it'd simplify the vfio-ccw 
code, but I don't think this lets you tell the difference between a READ 
(x02) and a NOP (x03) or any other control-type CCW.  Ditto 
read-backward versus TIC.  :-(

>       ccw_dstream_rewind(cds);
>       if (!(cds->flags & CDS_F_IDA)) {
>           cds->op_handler = ccw_dstream_rw_noflags;
> diff --git a/include/hw/s390x/css.h b/include/hw/s390x/css.h
> index aae19c427229..7cc183ef4366 100644
> --- a/include/hw/s390x/css.h
> +++ b/include/hw/s390x/css.h
> @@ -97,6 +97,7 @@ typedef struct CcwDataStream {
>       int (*op_handler)(struct CcwDataStream *cds, void *buff, int len,
>                         CcwDataStreamOp op);
>       hwaddr cda;
> +    bool do_skip;
>   } CcwDataStream;
>   
>   /*
>
Re: [Qemu-devel] [PATCH RFC] s390/css: handle CCW_FLAG_SKIP
Posted by Cornelia Huck 4 years, 11 months ago 
On Mon, 6 May 2019 16:58:03 -0400
Eric Farman <farman@linux.ibm.com> wrote:

> On 5/6/19 1:17 PM, Cornelia Huck wrote:
> > If a ccw has CCW_FLAG_SKIP set, and the command is of type
> > read, read backwards, or sense, no data should be written
> > to the guest for that command.
> > 
> > Signed-off-by: Cornelia Huck <cohuck@redhat.com>
> > ---
> > 
> > Only extremely lightly tested (i.e., can boot a guest.)
> > 
> > ---
> >   hw/s390x/css.c         | 22 ++++++++++++++++++----
> >   include/hw/s390x/css.h |  1 +
> >   2 files changed, 19 insertions(+), 4 deletions(-)
> > 
> > diff --git a/hw/s390x/css.c b/hw/s390x/css.c
> > index 8fc9e35ba5d3..6ee31cc2e08f 100644
> > --- a/hw/s390x/css.c
> > +++ b/hw/s390x/css.c
> > @@ -830,8 +830,12 @@ static int ccw_dstream_rw_noflags(CcwDataStream *cds, void *buff, int len,
> >       if (op == CDS_OP_A) {
> >           goto incr;
> >       }
> > -    ret = address_space_rw(&address_space_memory, cds->cda,
> > -                           MEMTXATTRS_UNSPECIFIED, buff, len, op);
> > +    if (!cds->do_skip) {
> > +        ret = address_space_rw(&address_space_memory, cds->cda,
> > +                               MEMTXATTRS_UNSPECIFIED, buff, len, op);
> > +    } else {
> > +        ret = 0;
> > +    }
> >       if (ret != MEMTX_OK) {
> >           cds->flags |= CDS_F_STREAM_BROKEN;
> >           return -EINVAL;
> > @@ -928,8 +932,13 @@ static int ccw_dstream_rw_ida(CcwDataStream *cds, void *buff, int len,
> >       do {
> >           iter_len = MIN(len, cont_left);
> >           if (op != CDS_OP_A) {
> > -            ret = address_space_rw(&address_space_memory, cds->cda,
> > -                                   MEMTXATTRS_UNSPECIFIED, buff, iter_len, op);
> > +            if (!cds->do_skip) {
> > +                ret = address_space_rw(&address_space_memory, cds->cda,
> > +                                       MEMTXATTRS_UNSPECIFIED, buff, iter_len,
> > +                                       op);
> > +            } else {
> > +                ret = 0;
> > +            }
> >               if (ret != MEMTX_OK) {
> >                   /* assume inaccessible address */
> >                   ret = -EINVAL; /* channel program check */
> > @@ -968,6 +977,11 @@ void ccw_dstream_init(CcwDataStream *cds, CCW1 const *ccw, ORB const *orb)
> >   
> >       cds->count = ccw->count;
> >       cds->cda_orig = ccw->cda;
> > +    /* skip is only effective for read, read backwards, or sense commands */
> > +    cds->do_skip = (ccw->flags & CCW_FLAG_SKIP) &&
> > +        (ccw->cmd_code & CCW_CMD_BASIC_SENSE ||
> > +         ccw->cmd_code & 0x02 /* read */ ||
> > +         ccw->cmd_code & 0x0c /* read backwards */);  
> 
> I wish so badly that these checks work, since it'd simplify the vfio-ccw 
> code, but I don't think this lets you tell the difference between a READ 
> (x02) and a NOP (x03) or any other control-type CCW.  Ditto 
> read-backward versus TIC.  :-(

Drat, why is that never easy... I'll rework this check.

> 
> >       ccw_dstream_rewind(cds);
> >       if (!(cds->flags & CDS_F_IDA)) {
> >           cds->op_handler = ccw_dstream_rw_noflags;
> > diff --git a/include/hw/s390x/css.h b/include/hw/s390x/css.h
> > index aae19c427229..7cc183ef4366 100644
> > --- a/include/hw/s390x/css.h
> > +++ b/include/hw/s390x/css.h
> > @@ -97,6 +97,7 @@ typedef struct CcwDataStream {
> >       int (*op_handler)(struct CcwDataStream *cds, void *buff, int len,
> >                         CcwDataStreamOp op);
> >       hwaddr cda;
> > +    bool do_skip;
> >   } CcwDataStream;
> >   
> >   /*
> >   
>

Patchew 2.1-devel-0870f84

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