From: Fangyu Yu Date: Fri, 27 Feb 2026 11:26:40 +0000 (+0800) Subject: iommu/riscv: Stop polling when CQCSR reports an error X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b2e5684558edf3e9bbe18d0e0043854994eab1be;p=thirdparty%2Flinux.git iommu/riscv: Stop polling when CQCSR reports an error The cmdq wait loop busy-polls the consumer index until it advances or the software timeout expires. If the IOMMU has already signaled a command queue failure in CQCSR, continuing to poll for progress is pointless. Make riscv_iommu_queue_wait() also terminate the poll when any of these CQCSR error bits are observed. This helps the caller return earlier in failure cases and avoids spinning until the full timeout interval when the hardware has already reported an error. On single-core systems in particular, the current busy-wait can delay servicing the command-timeout interrupt until the software timeout expires (90s by default). Fixes: 856c0cfe5c5f ("iommu/riscv: Command and fault queue support") Signed-off-by: Fangyu Yu Signed-off-by: Joerg Roedel --- diff --git a/drivers/iommu/riscv/iommu.c b/drivers/iommu/riscv/iommu.c index aadfbc181138f..6ac7e3edef8aa 100644 --- a/drivers/iommu/riscv/iommu.c +++ b/drivers/iommu/riscv/iommu.c @@ -368,6 +368,8 @@ static int riscv_iommu_queue_wait(struct riscv_iommu_queue *queue, unsigned int timeout_us) { unsigned int cons = atomic_read(&queue->head); + unsigned int flags = RISCV_IOMMU_CQCSR_CQMF | RISCV_IOMMU_CQCSR_CMD_TO | + RISCV_IOMMU_CQCSR_CMD_ILL; /* Already processed by the consumer */ if ((int)(cons - index) > 0) @@ -375,6 +377,7 @@ static int riscv_iommu_queue_wait(struct riscv_iommu_queue *queue, /* Monitor consumer index */ return readx_poll_timeout(riscv_iommu_queue_cons, queue, cons, + (riscv_iommu_readl(queue->iommu, queue->qcr) & flags) || (int)(cons - index) > 0, 0, timeout_us); }