Re: [Qemu-devel] [PATCH 2/3] s390: Virtual channel subsystem support.

[Alexander Graf]

On 31.10.2012, at 17:24, Cornelia Huck wrote:

> Provide a mechanism for qemu to provide fully virtual subchannels to
> the guest. In the KVM case, this relies on the kernel's css support
> for I/O and machine check interrupt handling. The !KVM case handles
> interrupts on its own.
> 
> Signed-off-by: Cornelia Huck <address@hidden>
> ---
> hw/s390x/Makefile.objs     |    1 +
> hw/s390x/css.c             | 1209 ++++++++++++++++++++++++++++++++++++++++++++
> hw/s390x/css.h             |   90 ++++
> target-s390x/Makefile.objs |    2 +-
> target-s390x/cpu.h         |  232 +++++++++
> target-s390x/helper.c      |  146 ++++++
> target-s390x/ioinst.c      |  737 +++++++++++++++++++++++++++
> target-s390x/ioinst.h      |  213 ++++++++
> target-s390x/kvm.c         |  251 ++++++++-
> target-s390x/misc_helper.c |    6 +-
> 10 files changed, 2872 insertions(+), 15 deletions(-)
> create mode 100644 hw/s390x/css.c
> create mode 100644 hw/s390x/css.h
> create mode 100644 target-s390x/ioinst.c
> create mode 100644 target-s390x/ioinst.h
> 
> diff --git a/hw/s390x/Makefile.objs b/hw/s390x/Makefile.objs
> index 096dfcd..378b099 100644
> --- a/hw/s390x/Makefile.objs
> +++ b/hw/s390x/Makefile.objs
> @@ -4,3 +4,4 @@ obj-y := $(addprefix ../,$(obj-y))
> obj-y += sclp.o
> obj-y += event-facility.o
> obj-y += sclpquiesce.o sclpconsole.o
> +obj-y += css.o
> diff --git a/hw/s390x/css.c b/hw/s390x/css.c
> new file mode 100644
> index 0000000..9adffb3
> --- /dev/null
> +++ b/hw/s390x/css.c
> @@ -0,0 +1,1209 @@
> +/*
> + * Channel subsystem base support.
> + *
> + * Copyright 2012 IBM Corp.
> + * Author(s): Cornelia Huck <address@hidden>
> + *
> + * 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 "qemu-thread.h"
> +#include "qemu-queue.h"
> +#include <hw/qdev.h>
> +#include "bitops.h"
> +#include "kvm.h"
> +#include "cpu.h"
> +#include "ioinst.h"
> +#include "css.h"
> +#include "virtio-ccw.h"
> +
> +typedef struct CrwContainer {
> +    CRW crw;
> +    QTAILQ_ENTRY(CrwContainer) sibling;
> +} CrwContainer;
> +
> +typedef struct ChpInfo {
> +    uint8_t in_use;
> +    uint8_t type;
> +    uint8_t is_virtual;
> +} ChpInfo;
> +
> +typedef struct SubchSet {
> +    SubchDev *sch[MAX_SCHID + 1];
> +    unsigned long schids_used[BITS_TO_LONGS(MAX_SCHID + 1)];
> +    unsigned long devnos_used[BITS_TO_LONGS(MAX_SCHID + 1)];
> +} SubchSet;
> +
> +typedef struct CssImage {
> +    SubchSet *sch_set[MAX_SSID + 1];
> +    ChpInfo chpids[MAX_CHPID + 1];
> +} CssImage;
> +
> +typedef struct ChannelSubSys {
> +    QTAILQ_HEAD(, CrwContainer) pending_crws;
> +    bool do_crw_mchk;
> +    bool crws_lost;
> +    uint8_t max_cssid;
> +    uint8_t max_ssid;
> +    bool chnmon_active;
> +    uint64_t chnmon_area;
> +    CssImage *css[MAX_CSSID + 1];
> +    uint8_t default_cssid;
> +} ChannelSubSys;
> +
> +static ChannelSubSys *channel_subsys;
> +
> +int css_create_css_image(uint8_t cssid, bool default_image)
> +{
> +    if (cssid > MAX_CSSID) {
> +        return -EINVAL;
> +    }
> +    if (channel_subsys->css[cssid]) {
> +        return -EBUSY;
> +    }
> +    channel_subsys->css[cssid] = g_try_malloc0(sizeof(CssImage));
> +    if (!channel_subsys->css[cssid]) {
> +        return -ENOMEM;
> +    }
> +    if (default_image) {
> +        channel_subsys->default_cssid = cssid;
> +    }
> +    return 0;
> +}
> +
> +static void css_write_phys_pmcw(uint64_t addr, PMCW *pmcw)
> +{
> +    int i;
> +    uint32_t offset = 0;
> +    struct copy_pmcw {
> +        uint32_t intparm;
> +        uint16_t flags;
> +        uint16_t devno;
> +        uint8_t lpm;
> +        uint8_t pnom;
> +        uint8_t lpum;
> +        uint8_t pim;
> +        uint16_t mbi;
> +        uint8_t pom;
> +        uint8_t pam;
> +        uint8_t chpid[8];
> +        uint32_t chars;
> +    } *copy;

This needs to be packed. Also, it might be a good idea to separate the struct 
definition from the actual code ;).

> +
> +    copy = (struct copy_pmcw *)pmcw;

This will break on any system that doesn't coincidently stick to the same 
bitfield order as s390x. Please drop any usage of bitfields in QEMU source code 
:).

> +    stl_phys(addr + offset, copy->intparm);
> +    offset += sizeof(copy->intparm);

Can't you just use cpu_physical_memory_map() and assign things left and right 
as you see fit? Or prepare the target endianness struct on the stack and 
cpu_physical_memory_read/write it from/to guest memory.

Also, please split this patch into smaller patches :). As it is now it's very 
hard to review. However, apart from the above issues (which may happen in other 
places of the code further down, I just didn't comment then) I couldn't see 
major problems so far. But please split it nevertheless so that I have an 
easier time reviewing it :)


Alex