Re: [PATCH v3 1/3] hw/misc/iommu-testdev: support PCI MSI test writes

On 7/27/2026 10:28 AM, [email protected] wrote:
>  From 84574de55c0f63f0963b3e5e0d477b18de91cf33 Mon Sep 17 00:00:00 2001
> From: Flavien Solt <[email protected]>
> Date: Sun, 26 Jul 2026 17:51:16 +0800
> Subject: [PATCH v3 1/3] hw/misc/iommu-testdev: support PCI MSI test writes
>
> iommu-testdev writes ITD_DMA_WRITE_VAL with unspecified requester
> attributes. RISC-V MSI remapping tests need to select an interrupt
> identity in the payload. The MSI trap also identifies the device through
> MemTxAttrs.requester_id.
>
> Add a write-value register with the existing constant as its reset
> default. Populate the requester ID from the PCI function. Existing
> translation tests retain their payload while interrupt-remapping tests
> can issue a valid MSI for the test device.
>
> Signed-off-by: Flavien Solt <[email protected]>
> Reviewed-by: Tao Tang <[email protected]>
Reviewed-by: Nutty Liu <[email protected]>

Thanks,
Nutty
> ---
>   hw/misc/iommu-testdev.c         | 14 ++++++++++++--
>   include/hw/misc/iommu-testdev.h |  1 +
>   2 files changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/hw/misc/iommu-testdev.c b/hw/misc/iommu-testdev.c
> index 15eb6de..6428a57 100644
> --- a/hw/misc/iommu-testdev.c
> +++ b/hw/misc/iommu-testdev.c
> @@ -28,6 +28,7 @@ struct IOMMUTestDevState {
>       uint64_t dma_paddr;
>       uint32_t dma_len;
>       uint32_t dma_result;
> +    uint32_t dma_write_val;
>       bool dma_armed; /* armed until a trigger consumes the request */
>
>       AddressSpace *dma_as;   /* IOMMU-mediated DMA AS for this device */
> @@ -80,6 +81,7 @@ static void iommu_testdev_maybe_run_dma(IOMMUTestDevState *s)
>
>       /* Initialize MemTxAttrs from generic register. */
>       attrs.secure = ITD_ATTRS_GET_SECURE(s->dma_attrs_cfg);
> +    attrs.requester_id = pci_requester_id(&s->parent_obj);
>
>       space_valid = ITD_ATTRS_GET_SPACE_VALID(s->dma_attrs_cfg);
>       if (space_valid) {
> @@ -97,12 +99,12 @@ static void
> iommu_testdev_maybe_run_dma(IOMMUTestDevState *s)
>
>       as = s->dma_as;
>
> -    /* Step 1: Write ITD_DMA_WRITE_VAL to DMA address */
> +    /* Step 1: Write the configured test value to DMA address */
>       trace_iommu_testdev_dma_write(s->dma_vaddr, s->dma_len);
>
>       for (int i = 0; i < s->dma_len; i++) {
>           /* Data is written in little-endian order */
> -        write_buf[i] = (ITD_DMA_WRITE_VAL >> ((i % 4) * 8)) & 0xff;
> +        write_buf[i] = (s->dma_write_val >> ((i % 4) * 8)) & 0xff;
>       }
>       write_res = dma_memory_write(as, s->dma_vaddr, write_buf,
>                                    s->dma_len, attrs);
> @@ -186,6 +188,9 @@ static uint64_t iommu_testdev_mmio_read(void
> *opaque, hwaddr addr,
>       case ITD_REG_DMA_ATTRS:
>           value = s->dma_attrs_cfg;
>           break;
> +    case ITD_REG_DMA_WRITE_VAL:
> +        value = s->dma_write_val;
> +        break;
>       default:
>           value = 0;
>           break;
> @@ -240,6 +245,9 @@ static void iommu_testdev_mmio_write(void *opaque,
> hwaddr addr, uint64_t val,
>       case ITD_REG_DMA_ATTRS:
>           s->dma_attrs_cfg = data;
>           break;
> +    case ITD_REG_DMA_WRITE_VAL:
> +        s->dma_write_val = data;
> +        break;
>       default:
>           break;
>       }
> @@ -263,6 +271,7 @@ static void iommu_testdev_realize(PCIDevice *pdev,
> Error **errp)
>       s->dma_paddr = 0;
>       s->dma_len = 0;
>       s->dma_result = ITD_DMA_RESULT_IDLE;
> +    s->dma_write_val = ITD_DMA_WRITE_VAL;
>       s->dma_armed = false;
>       s->dma_attrs_cfg = ITD_ATTRS_SET_SPACE(0, ITD_ATTRS_SPACE_NONSECURE);
>       s->dma_as = pci_device_iommu_address_space(pdev);
> @@ -280,6 +289,7 @@ static void iommu_testdev_reset(DeviceState *dev)
>       s->dma_paddr = 0;
>       s->dma_len = 0;
>       s->dma_result = ITD_DMA_RESULT_IDLE;
> +    s->dma_write_val = ITD_DMA_WRITE_VAL;
>       s->dma_armed = false;
>       s->dma_attrs_cfg = ITD_ATTRS_SET_SPACE(0, ITD_ATTRS_SPACE_NONSECURE);
>   }
> diff --git a/include/hw/misc/iommu-testdev.h b/include/hw/misc/iommu-testdev.h
> index 3383659..2f4e931 100644
> --- a/include/hw/misc/iommu-testdev.h
> +++ b/include/hw/misc/iommu-testdev.h
> @@ -81,6 +81,7 @@ enum {
>       ITD_REG_DMA_ATTRS       = 0x18,
>       ITD_REG_DMA_GPA_LO      = 0x1c,
>       ITD_REG_DMA_GPA_HI      = 0x20,
> +    ITD_REG_DMA_WRITE_VAL   = 0x24,
>       BAR0_SIZE               = 0x1000,
>   };
>