Re: [PATCH v3] block: make BlockConf.*_size properties 32-bit

[Roman Kagan]

On Wed, Apr 29, 2020 at 02:59:31PM +0200, Philippe Mathieu-Daudé wrote:
> On 4/29/20 2:19 PM, Roman Kagan wrote:
> > On Wed, Apr 29, 2020 at 11:41:04AM +0200, Philippe Mathieu-Daudé wrote:
> > > Cc'ing virtio-blk and scsi maintainers.
> > > 
> > > On 4/29/20 11:18 AM, Roman Kagan wrote:
> > > > Devices (virtio-blk, scsi, etc.) and the block layer are happy to use
> > > > 32-bit for logical_block_size, physical_block_size, and min_io_size.
> > > > However, the properties in BlockConf are defined as uint16_t limiting
> > > > the values to 32768.
> > > > 
> > > > This appears unnecessary tight, and we've seen bigger block sizes handy
> > > > at times.
> > > > 
> > > > Make them 32 bit instead and lift the limitation up to 2 MiB which
> > > > appears to be good enough for everybody, and matches the qcow2 cluster
> > > > size limit.
> > > > 
> > > > As the values can now be fairly big and awkward to type, make the
> > > > property setter accept common size suffixes (k, m).
> > > > 
> > > > Signed-off-by: Roman Kagan <address@hidden>
> > > > Reviewed-by: Eric Blake <address@hidden>
> > > > ---
> > > > v2 -> v3:
> > > > - mention qcow2 cluster size limit in the log and comment [Eric]
> > > > 
> > > > v1 -> v2:
> > > > - cap the property at 2 MiB [Eric]
> > > > - accept size suffixes
> > > > 
> > > >    include/hw/block/block.h     |  8 ++++----
> > > >    include/hw/qdev-properties.h |  2 +-
> > > >    hw/core/qdev-properties.c    | 34 ++++++++++++++++++++++++----------
> > > >    3 files changed, 29 insertions(+), 15 deletions(-)
> > > > 
> > > > diff --git a/include/hw/block/block.h b/include/hw/block/block.h
> > > > index d7246f3862..9dd6bba56a 100644
> > > > --- a/include/hw/block/block.h
> > > > +++ b/include/hw/block/block.h
> > > > @@ -18,9 +18,9 @@
> > > >    typedef struct BlockConf {
> > > >        BlockBackend *blk;
> > > > -    uint16_t physical_block_size;
> > > > -    uint16_t logical_block_size;
> > > > -    uint16_t min_io_size;
> > > > +    uint32_t physical_block_size;
> > > > +    uint32_t logical_block_size;
> > > > +    uint32_t min_io_size;
> > > >        uint32_t opt_io_size;
> > > >        int32_t bootindex;
> > > >        uint32_t discard_granularity;
> > > > @@ -51,7 +51,7 @@ static inline unsigned int 
> > > > get_physical_block_exp(BlockConf *conf)
> > > >                              _conf.logical_block_size),                 
> > > >    \
> > > >        DEFINE_PROP_BLOCKSIZE("physical_block_size", _state,             
> > > >    \
> > > >                              _conf.physical_block_size),                
> > > >    \
> > > > -    DEFINE_PROP_UINT16("min_io_size", _state, _conf.min_io_size, 0),   
> > > >  \
> > > > +    DEFINE_PROP_UINT32("min_io_size", _state, _conf.min_io_size, 0),   
> > > >  \
> > > >        DEFINE_PROP_UINT32("opt_io_size", _state, _conf.opt_io_size, 0), 
> > > >    \
> > > >        DEFINE_PROP_UINT32("discard_granularity", _state,                
> > > >    \
> > > >                           _conf.discard_granularity, -1),               
> > > >    \
> > > > diff --git a/include/hw/qdev-properties.h b/include/hw/qdev-properties.h
> > > > index f161604fb6..f9e0f8c041 100644
> > > > --- a/include/hw/qdev-properties.h
> > > > +++ b/include/hw/qdev-properties.h
> > > > @@ -197,7 +197,7 @@ extern const PropertyInfo qdev_prop_pcie_link_width;
> > > >    #define DEFINE_PROP_BIOS_CHS_TRANS(_n, _s, _f, _d) \
> > > >        DEFINE_PROP_SIGNED(_n, _s, _f, _d, qdev_prop_bios_chs_trans, int)
> > > >    #define DEFINE_PROP_BLOCKSIZE(_n, _s, _f) \
> > > > -    DEFINE_PROP_UNSIGNED(_n, _s, _f, 0, qdev_prop_blocksize, uint16_t)
> > > > +    DEFINE_PROP_UNSIGNED(_n, _s, _f, 0, qdev_prop_blocksize, uint32_t)
> > > >    #define DEFINE_PROP_PCI_HOST_DEVADDR(_n, _s, _f) \
> > > >        DEFINE_PROP(_n, _s, _f, qdev_prop_pci_host_devaddr, 
> > > > PCIHostDeviceAddress)
> > > >    #define DEFINE_PROP_OFF_AUTO_PCIBAR(_n, _s, _f, _d) \
> > > > diff --git a/hw/core/qdev-properties.c b/hw/core/qdev-properties.c
> > > > index 2047114fca..e673f3c43f 100644
> > > > --- a/hw/core/qdev-properties.c
> > > > +++ b/hw/core/qdev-properties.c
> > > > @@ -14,6 +14,7 @@
> > > >    #include "qapi/visitor.h"
> > > >    #include "chardev/char.h"
> > > >    #include "qemu/uuid.h"
> > > > +#include "qemu/units.h"
> > > >    void qdev_prop_set_after_realize(DeviceState *dev, const char *name,
> > > >                                      Error **errp)
> > > > @@ -729,30 +730,42 @@ const PropertyInfo qdev_prop_pci_devfn = {
> > > >    /* --- blocksize --- */
> > > > +/* lower limit is sector size */
> > > > +#define MIN_BLOCK_SIZE          512
> > > > +#define MIN_BLOCK_SIZE_STR      "512 B"
> > > > +/*
> > > > + * upper limit is arbitrary, 2 MiB looks sufficient for all sensible 
> > > > uses, and
> > > > + * matches qcow2 cluster size limit
> > > > + */
> > > > +#define MAX_BLOCK_SIZE          (2 * MiB)
> > > > +#define MAX_BLOCK_SIZE_STR      "2 MiB"
> > > > +
> > > >    static void set_blocksize(Object *obj, Visitor *v, const char *name,
> > > >                              void *opaque, Error **errp)
> > > >    {
> > > >        DeviceState *dev = DEVICE(obj);
> > > >        Property *prop = opaque;
> > > > -    uint16_t value, *ptr = qdev_get_prop_ptr(dev, prop);
> > > > +    uint32_t *ptr = qdev_get_prop_ptr(dev, prop);
> > > > +    uint64_t value;
> > > >        Error *local_err = NULL;
> > > > -    const int64_t min = 512;
> > > > -    const int64_t max = 32768;
> > > >        if (dev->realized) {
> > > >            qdev_prop_set_after_realize(dev, name, errp);
> > > >            return;
> > > >        }
> > > > -    visit_type_uint16(v, name, &value, &local_err);
> > > > +    visit_type_size(v, name, &value, &local_err);
> > > >        if (local_err) {
> > > >            error_propagate(errp, local_err);
> > > >            return;
> > > >        }
> > > >        /* value of 0 means "unset" */
> > > > -    if (value && (value < min || value > max)) {
> > > > -        error_setg(errp, QERR_PROPERTY_VALUE_OUT_OF_RANGE,
> > > > -                   dev->id ? : "", name, (int64_t)value, min, max);
> > > > +    if (value && (value < MIN_BLOCK_SIZE || value > MAX_BLOCK_SIZE)) {
> > > > +        error_setg(errp,
> > > > +                   "Property %s.%s doesn't take value %" PRIu64
> > > > +                   " (minimum: " MIN_BLOCK_SIZE_STR
> > > > +                   ", maximum: " MAX_BLOCK_SIZE_STR ")",
> > > > +                   dev->id ? : "", name, value);
> > > >            return;
> > > >        }
> > > > @@ -768,9 +781,10 @@ static void set_blocksize(Object *obj, Visitor *v, 
> > > > const char *name,
> > > >    }
> > > >    const PropertyInfo qdev_prop_blocksize = {
> > > > -    .name  = "uint16",
> > > > -    .description = "A power of two between 512 and 32768",
> > > > -    .get   = get_uint16,
> > > > +    .name  = "size",
> > > > +    .description = "A power of two between " MIN_BLOCK_SIZE_STR
> > > > +                   " and " MAX_BLOCK_SIZE_STR,
> > > > +    .get   = get_uint32,
> > > >        .set   = set_blocksize,
> > > >        .set_default_value = set_default_value_uint,
> > > >    };
> > > > 
> > > 
> > > 1/ Don't you need to update SCSIBlockLimits too?
> > 
> > I guess you mean SCSIBlockLimits.min_io_size which is the only uint16_t
> > field there, do you?
> 
> Yes.
> 
> > 
> > > 2/ It seems hw/block/virtio-blk.c can get underflow now.
> > 
> > Both SCSIBlockLimits.min_io_size and virtio_blk_config.min_io_size are
> > expressed in logical blocks so there appears to be no problem here.
> > 
> > > Maybe you miss this change:
> > > 
> > > -- >8 --
> > > diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
> > > --- a/hw/block/virtio-blk.c
> > > +++ b/hw/block/virtio-blk.c
> > > @@ -917,7 +917,7 @@ static void virtio_blk_update_config(VirtIODevice 
> > > *vdev,
> > > uint8_t *config)
> > >                    s->conf.seg_max_adjust ? s->conf.queue_size - 2 : 128 -
> > > 2);
> > >       virtio_stw_p(vdev, &blkcfg.geometry.cylinders, conf->cyls);
> > >       virtio_stl_p(vdev, &blkcfg.blk_size, blk_size);
> > > -    virtio_stw_p(vdev, &blkcfg.min_io_size, conf->min_io_size / 
> > > blk_size);
> > > +    virtio_stl_p(vdev, &blkcfg.min_io_size, conf->min_io_size / 
> > > blk_size);
> > 
> > The width of this field in the device's config space is defined in the
> > spec and can't be changed.
> > 
> > Nor is there any need due to this patch.
> 
> OK, thanks :)

May I count this as an r-b? :)

Thanks,
Roman.