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

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 4/30/20 11:25 AM, Roman Kagan wrote:
> 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 <rvkagan@yandex-team.ru>
>>>>> Reviewed-by: Eric Blake <eblake@redhat.com>
>>>>> ---
>>>>> 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? :)

Unfortunately no, because my comments proved I don't know this code 
enough :/

> 
> Thanks,
> Roman.
>