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

[Flavien Solt]

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. The problem is that riscv_iommu_msi_write() currently reads the MRIF 
interrupt-enable doubleword and suppresses the notice MSI when the bit is zero.

This patch removes the enable-word read and always sends the notice MSI after 
updating the MRIF pending bit.

Fixes: 0c54acb8243d ("hw/riscv: add RISC-V IOMMU base emulation")
Cc: qemu-sta...@nongnu.org
Signed-off-by: Flavien Solt <flav...@nus.edu.sg>
---
Tested with a deterministic qtest using qemu-system-riscv64.

After this patch we get:
  enable=0: pending=0x20 notice=0x12d
  enable=1: pending=0x20 notice=0x12d

 hw/riscv/riscv-iommu.c | 15 +--------------
 1 file changed, 1 insertion(+), 14 deletions(-)

diff --git a/hw/riscv/riscv-iommu.c b/hw/riscv/riscv-iommu.c
index f6865d1..9627cab 100644
--- a/hw/riscv/riscv-iommu.c
+++ b/hw/riscv/riscv-iommu.c
@@ -788,20 +788,7 @@ 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) |
           (get_field(pte[1], RISCV_IOMMU_MSI_MRIF_NID_MSB) << 10);

base-commit: 499039798cdad7d86b787fec0eaf1da4151c0f05
--
2.54.0


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