On 2021-11-29 10:55, Will Deacon wrote:
Hi Thomas,
On Sat, Nov 27, 2021 at 02:20:59AM +0100, Thomas Gleixner wrote:
Let the core code fiddle with the MSI descriptor retrieval.
Signed-off-by: Thomas Gleixner <[email protected]>
---
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 19 +++----------------
1 file changed, 3 insertions(+), 16 deletions(-)
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -3154,7 +3154,6 @@ static void arm_smmu_write_msi_msg(struc
static void arm_smmu_setup_msis(struct arm_smmu_device *smmu)
{
- struct msi_desc *desc;
int ret, nvec = ARM_SMMU_MAX_MSIS;
struct device *dev = smmu->dev;
@@ -3182,21 +3181,9 @@ static void arm_smmu_setup_msis(struct a
return;
}
- for_each_msi_entry(desc, dev) {
- switch (desc->msi_index) {
- case EVTQ_MSI_INDEX:
- smmu->evtq.q.irq = desc->irq;
- break;
- case GERROR_MSI_INDEX:
- smmu->gerr_irq = desc->irq;
- break;
- case PRIQ_MSI_INDEX:
- smmu->priq.q.irq = desc->irq;
- break;
- default: /* Unknown */
- continue;
- }
- }
+ smmu->evtq.q.irq = msi_get_virq(dev, EVTQ_MSI_INDEX);
+ smmu->gerr_irq = msi_get_virq(dev, GERROR_MSI_INDEX);
+ smmu->priq.q.irq = msi_get_virq(dev, PRIQ_MSI_INDEX);
Prviously, if retrieval of the MSI failed then we'd fall back to wired
interrupts. Now, I think we'll clobber the interrupt with 0 instead. Can
we make the assignments to smmu->*irq here conditional on the MSI being
valid, please?
I was just looking at that too, but reached the conclusion that it's
probably OK, since consumption of this value later is gated on
ARM_SMMU_FEAT_PRI, so the fact that it changes from 0 to an error value
in the absence of PRI should make no practical difference. If we don't
have MSIs at all, we'd presumably still fail earlier either at the
dev->msi_domain check or upon trying to allocate the vectors, so we'll
still fall back to any previously-set wired values before getting here.
The only remaining case is if we've *successfully* allocated the
expected number of vectors yet are then somehow unable to retrieve one
or more of them - presumably the system has to be massively borked for
that to happen, at which point do we really want to bother trying to
reason about anything?
Robin.
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