On Tue, May 31, 2022 at 9:19 AM Will Deacon <will@xxxxxxxxxx> wrote: > > On Tue, May 31, 2022 at 09:15:22AM -0700, Rob Clark wrote: > > On Tue, May 31, 2022 at 8:46 AM Will Deacon <will@xxxxxxxxxx> wrote: > > > > > > On Fri, May 27, 2022 at 11:28:56PM +0200, Konrad Dybcio wrote: > > > > From: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxxx> > > > > > > > > As specified in this driver, the context banks are 0x1000 apart. > > > > Problem is that sometimes the context number (our asid) does not > > > > match this logic and we end up using the wrong one: this starts > > > > being a problem in the case that we need to send TZ commands > > > > to do anything on a specific context. > > > > > > I don't understand this. The ASID is a software construct, so it shouldn't > > > matter what we use. If it does matter, then please can you explain why? The > > > fact that the context banks are 0x1000 apart seems unrelated. > > > > I think the connection is that mapping from ctx bank to ASID is 1:1 > > But in what sense? How is the ASID used beyond a tag in the TLB? The commit > message hints at "TZ commands" being a problem. > > I'm not doubting that this is needed to make the thing work, I just don't > understand why. (disclaimer, it has been quite a while since I've looked at the smmu setup with earlier tz, ie. things that use qcom_iommu, but from memory...) We cannot actually assign the context banks ourselves, so in the dt bindings the "ASID" is actually the context bank index. I don't remember exactly if this was a limitation of the tz interface, or result of not being able to program the smmu's global registers ourselves. BR, -R
