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From: Tomasz Nowicki <tn@semihalf.com>
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Date: Thu, 13 Jul 2017 14:57:54 +0200
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Subject: Re: [Qemu-devel] [RFC v5 2/8] hw/arm/smmuv3: smmuv3 emulation model
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To: Eric Auger <eric.auger@redhat.com>, eric.auger.pro@gmail.com, peter.maydell@linaro.org, qemu-arm@nongnu.org, qemu-devel@nongnu.org, alex.williamson@redhat.com, prem.mallappa@gmail.com
Cc: drjones@redhat.com, christoffer.dall@linaro.org, Radha.Chintakuntla@cavium.com, Sunil.Goutham@cavium.com, mohun106@gmail.com, tcain@qti.qualcomm.com, bharat.bhushan@nxp.com, mst@redhat.com, will.deacon@arm.com, jean-philippe.brucker@arm.com, robin.murphy@arm.com, peterx@redhat.com, edgar.iglesias@gmail.com

Hi Eric,

On 09.07.2017 22:51, Eric Auger wrote:
> From: Prem Mallappa <prem.mallappa@broadcom.com>
> 
> Introduces the SMMUv3 derived model. This is based on
> System MMUv3 specification (v17).
> 
> Signed-off-by: Prem Mallappa <prem.mallappa@broadcom.com>
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> 
> ---
> v4 -> v5:
> - change smmuv3_translate proto (IOMMUAccessFlags flag)
> - has_stagex replaced by is_ste_stagex
> - smmu_cfg_populate removed
> - added smmuv3_decode_config and reworked error management
> - remwork the naming of IOMMU mrs
> - fix SMMU_CMDQ_CONS offset
> 

[...]

> +
> +static void smmu_update_qreg(SMMUV3State *s, SMMUQueue *q, hwaddr reg,
> +                             uint32_t off, uint64_t val, unsigned size)
> +{
> +   if (size == 8 && off == 0) {
> +        smmu_write64_reg(s, reg, val);

Based on my observation we never get here.

If I read the code correctly, 
memory_region_dispatch_{write|read}()->memory_region_{write|read}_accessor() 
will cut all 8-bytes accesses into 4-bytes slices. However, this makes 
my SMMUv3 register handling happy:

  static const MemoryRegionOps smmu_mem_ops = {
      .read = smmu_read_mmio,
      .write = smmu_write_mmio,
      .endianness = DEVICE_LITTLE_ENDIAN,
      .valid = {
          .min_access_size = 4,
          .max_access_size = 8,
      },
+    .impl = {
+        .min_access_size = 4,
+	.max_access_size = 8,
+    },
  };

Thanks,
Tomasz