Re: [PATCH v3 2/3] hw/riscv/riscv-iommu.c: always send MRIF notice MSI

[Chao Liu <chao.liu@processmission.com>]

On Sun, Jul 26, 2026 at 07:28:21PM +0800, flavien.solt97@gmail.com wrote:
> From 42f759d7e7f4eca064638622d52aa38be11b956b Mon Sep 17 00:00:00 2001
> From: Flavien Solt <flavien.solt97@gmail.com>
> Date: Sun, 26 Jul 2026 17:52:03 +0800
> Subject: [PATCH v3 2/3] hw/riscv/riscv-iommu.c: always send MRIF notice MSI
> 
> The AIA specification requires an IOMMU to send the configured notice
> MSI after storing an MSI to an MRIF, even when the corresponding
> interrupt-enable bit is clear.
> 
> riscv_iommu_msi_write() currently reads the MRIF interrupt-enable
> doubleword and suppresses the notice MSI when the matching bit is zero.
> This makes notice delivery depend on a bit that AIA requires the IOMMU
> to ignore.
> 
> Remove the enable-word read and send the notice MSI unconditionally
> after updating the MRIF pending bit.
> 
> Fixes: 0c54acb8243d ("hw/riscv: add RISC-V IOMMU base emulation")
> Cc: qemu-stable@nongnu.org
> Reviewed-by: Andrew Jones <andrew.jones@oss.qualcomm.com>
> Signed-off-by: Flavien Solt <flavien.solt97@gmail.com>
Reviewed-by: Chao Liu <chao.liu@processmission.com>

Thanks,
Chao

> ---
>  hw/riscv/riscv-iommu.c | 13 -------------
>  1 file changed, 13 deletions(-)
> 
> diff --git a/hw/riscv/riscv-iommu.c b/hw/riscv/riscv-iommu.c
> index f6865d1..2bbac30 100644
> --- a/hw/riscv/riscv-iommu.c
> +++ b/hw/riscv/riscv-iommu.c
> @@ -788,19 +788,6 @@ static MemTxResult
> riscv_iommu_msi_write(RISCVIOMMUState *s,
>          goto err;
>      }
> 
> -    /* Get MRIF enable bits */
> -    addr = addr + sizeof(intn);
> -    res = dma_memory_read(s->target_as, addr, &intn, sizeof(intn), attrs);
> -    if (res != MEMTX_OK) {
> -        cause = RISCV_IOMMU_FQ_CAUSE_MSI_LOAD_FAULT;
> -        goto err;
> -    }
> -
> -    if (!(intn & data)) {
> -        /* notification disabled, MRIF update completed. */
> -        return MEMTX_OK;
> -    }
> -
>      /* Send notification message */
>      addr = PPN_PHYS(get_field(pte[1], RISCV_IOMMU_MSI_MRIF_NPPN));
>      n190 = get_field(pte[1], RISCV_IOMMU_MSI_MRIF_NID) |
> -- 
> 2.54.0