On Mon, Aug 19, 2019 at 01:44:37PM +0100, Peter Maydell wrote: > On Fri, 16 Aug 2019 at 13:58, Peter Maydell <peter.mayd...@linaro.org> wrote: > > > > The translation table walk for an ATS instruction can result in > > various faults. In general these are just reported back via the > > PAR_EL1 fault status fields, but in some cases the architecture > > requires that the fault is turned into an exception: > > * synchronous stage 2 faults of any kind during AT S1E0* and > > AT S1E1* instructions executed from NS EL1 fault to EL2 or EL3 > > * synchronous external aborts are taken as Data Abort exceptions > > > > (This is documented in the v8A Arm ARM DDI0487A.e D5.2.11 and G5.13.4.) > > > > I noticed this by code inspection back last year sometime when > > I was investigating a guest boot failure that turned out to be > > due to an entirely different cause. I got about halfway through > > trying to code up a fix before I realised it was irrelevant to > > that bug. This patchset is just tidying up and completing that > > work so it doesn't get lost. > > > > Use of ATS insns in the cases where they might actually fault > > is quite rare (obviously nobody sets up page tables where there's > > no memory and they'll take external aborts, and even for the > > "take a hyp trap for a stage 2 fault" case you need a setup > > with a hypervisor and a guest that uses ATS insns, and Linux as > > a guest doesn't use ATS at all. So my testing of this patchset > > has been more "check it doesn't break things" rather than > > actively finding and testing a use of the throw-an-exception path... > > I'm told that Xen for Arm makes more active use of ATS > instructions, so I've cc'd a few Xen people -- do any > of you have handy testing setups to try running Xen in > emulation under QEMU? Configs where the guest (EL1) actually > uses ATS instructions are the particularly interesting point > for this patchset. > > (if there's a good set of instructions for creating a test > image I could probably add it to the ad-hoc set of things > I sometimes test with.)
Hi, All tests passed. Tested-by: Edgar E. Iglesias <edgar.igles...@xilinx.com> Cheers, Edgar
