On Fri, Jan 10, 2025 at 10:38:42AM -0800, Nicolin Chen wrote:
The virtual event queue should behave the same as if the physical event queue overflows, and that logic should be in the smmu driver - this should return some Exxx to indicate the queue is filled.
Hmm, the driver only screams...
static irqreturn_t arm_smmu_evtq_thread(int irq, void *dev) { [...] /* * Not much we can do on overflow, so scream and pretend we're * trying harder. */ if (queue_sync_prod_in(q) == -EOVERFLOW) dev_err(smmu->dev, "EVTQ overflow detected -- events lost\n");
Well it must know from the HW somehow that the overflow has happened??
I supposed we will need a way to indicate lost events to userspace on top of this?
Perhaps another u32 flag in the arm_smmuv3_vevent struct to report an overflow. That said, what userspace/VMM will need to do with it?
Trigger the above code in the VM somehow?
Jason