[v2,1/2] ivshmem: fix misconfig of not_legacy_32bit

From: ZhuangYanying <ann.zhuangyanying@huawei.com>

After commit 5400c02, ivshmem_64bit renamed to not_legacy_32bit, 
and changed the implementation of this property.
Then use64 = 1, ~PCI_BASE_ADDRESS_MEM_TYPE_64 (default for ivshmem),
the actual use is the legacy model, 
can not support greater than or equal 1G mapping,
which is the opposite of configuration requirements.

Cc: qemu-stable@nongnu.org
Signed-off-by: Zhuang Yanying <ann.zhuangyanying@huawei.com>
Reviewed-by: Gonglei <arei.gonglei@huawei.com>
---
 hw/misc/ivshmem.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Zhuangyanying <ann.zhuangyanying@huawei.com> writes:

> From: ZhuangYanying <ann.zhuangyanying@huawei.com>
>
> After commit 5400c02, ivshmem_64bit renamed to not_legacy_32bit, 
> and changed the implementation of this property.
> Then use64 = 1, ~PCI_BASE_ADDRESS_MEM_TYPE_64 (default for ivshmem),
> the actual use is the legacy model, 
> can not support greater than or equal 1G mapping,
> which is the opposite of configuration requirements.
>
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Zhuang Yanying <ann.zhuangyanying@huawei.com>
> Reviewed-by: Gonglei <arei.gonglei@huawei.com>

I find the commit message hard to understand.  To improve it, let's
figure out what exactly is broken.

The sense of device ivshmem's property use64 is reverted: use64=0
enables the 64 bit memory bar, use64=1 disables it.  Default is 32 bit
unless pc-1.2 or older.  This regressed in commit 5400c02.  Before,
use64 had the correct sense, and the default was 64 bit unless pc-1.2 or
older.

Note that devices ivshmem-plain and ivshmem-doorbell always have a 64
bit memory bar, as intended.

> ---
>  hw/misc/ivshmem.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/hw/misc/ivshmem.c b/hw/misc/ivshmem.c
> index 230e51b..b897685 100644
> --- a/hw/misc/ivshmem.c
> +++ b/hw/misc/ivshmem.c
> @@ -858,7 +858,7 @@ static void ivshmem_common_realize(PCIDevice *dev, Error **errp)
>      pci_register_bar(dev, 0, PCI_BASE_ADDRESS_SPACE_MEMORY,
>                       &s->ivshmem_mmio);
>  
> -    if (!s->not_legacy_32bit) {
> +    if (s->not_legacy_32bit) {
>          attr |= PCI_BASE_ADDRESS_MEM_TYPE_64;
>      }

Thanks a lot for catching my mistake!

However, this breaks ivshmem-plain and ivshmem-doorbell.  You fix that
in the next patch, but that's no good, the two need to be squashed into
a single commit.

Suggested commit message for the squashed commit:

    ivshmem: Fix 64 bit memory bar configuration

    Device ivshmem property use64=0 is designed to make the device
    expose a 32 bit shared memory BAR instead of 64 bit one.  The
    default is a 64 bit BAR, except pc-1.2 and older retain a 32 bit
    BAR.  A 32 bit BAR can support only up to 1 GiB of shared memory.

    This worked as designed until commit 5400c02 accidentally flipped
    its sense: since then, we misinterpret use64=0 as use64=1 and vice
    versa.  Worse, the default got flipped as well.  Devices
    ivshmem-plain and ivshmem-doorbell are not affected.

    Fix by restoring the test of IVShmemState member not_legacy_32bit
    that got messed up in commit 5400c02.  Also update its
    initialization for devices ivhsmem-plain and ivshmem-doorbell.
    Without that, they'd regress to 32 bit BARs.

    Cc: qemu-stable@nongnu.org

Would that work for you?