[ Upstream commit 3a8990b8a778219327c5f8ecf10b5d81377b925a ]
On qcom msm8998, writing to the last context bank of lpass_q6_smmu
(base address 0x05100000) produces a system freeze & reboot.
The hardware/hypervisor reports 13 context banks for the LPASS SMMU
on msm8998, but only the first 12 are accessible...
Override the number of context banks
[ 2.546101] arm-smmu 5100000.iommu: probing hardware configuration...
[ 2.552439] arm-smmu 5100000.iommu: SMMUv2 with:
[ 2.558945] arm-smmu 5100000.iommu: stage 1 translation
[ 2.563627] arm-smmu 5100000.iommu: address translation ops
[ 2.568923] arm-smmu 5100000.iommu: non-coherent table walk
[ 2.574566] arm-smmu 5100000.iommu: (IDR0.CTTW overridden by FW configuration)
[ 2.580220] arm-smmu 5100000.iommu: stream matching with 12 register groups
[ 2.587263] arm-smmu 5100000.iommu: 13 context banks (0 stage-2 only)
[ 2.614447] arm-smmu 5100000.iommu: Supported page sizes: 0x63315000
[ 2.621358] arm-smmu 5100000.iommu: Stage-1: 36-bit VA -> 36-bit IPA
[ 2.627772] arm-smmu 5100000.iommu: preserved 0 boot mappings
Specifically, the crashes occur here:
qsmmu->bypass_cbndx = smmu->num_context_banks - 1;
arm_smmu_cb_write(smmu, qsmmu->bypass_cbndx, ARM_SMMU_CB_SCTLR, 0);
and here:
arm_smmu_write_context_bank(smmu, i);
arm_smmu_cb_write(smmu, i, ARM_SMMU_CB_FSR, ARM_SMMU_CB_FSR_FAULT);
It is likely that FW reserves the last context bank for its own use,
thus a simple work-around is: DON'T USE IT in Linux.
If we decrease the number of context banks, last one will be "hidden".
Signed-off-by: Marc Gonzalez <mgonzalez@freebox.fr>
Reviewed-by: Caleb Connolly <caleb.connolly@linaro.org>
Reviewed-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20240820-smmu-v3-1-2f71483b00ec@freebox.fr
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
440ca404fc