On 27.03.2024 10:04 PM, Volodymyr Babchuk wrote: > > Hi Konrad, > > Konrad Dybcio <konrad.dybcio@xxxxxxxxxx> writes: > >> On 27.03.2024 9:09 PM, Volodymyr Babchuk wrote: >>> It appears that hardware does not like cacheable accesses to this >>> region. Trying to access this shared memory region as Normal Memory >>> leads to secure interrupt which causes an endless loop somewhere in >>> Trust Zone. >>> >>> The only reason it is working right now is because Qualcomm Hypervisor >>> maps the same region as Non-Cacheable memory in Stage 2 translation >>> tables. The issue manifests if we want to use another hypervisor (like >>> Xen or KVM), which does not know anything about those specific >>> mappings. This patch fixes the issue by mapping the shared memory as >>> Write-Through. This removes dependency on correct mappings in Stage 2 >>> tables. >>> >>> I tested this on SA8155P with Xen. >>> >>> Signed-off-by: Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx> >>> --- >> >> Interesting.. >> >> +Doug, Rob have you ever seen this on Chrome? (FYI, Volodymyr, chromebooks >> ship with no qcom hypervisor) > > Well, maybe I was wrong when called this thing "hypervisor". All I know > that it sits in hyp.mbn partition and all what it does is setup EL2 > before switching to EL1 and running UEFI. > > In my experiments I replaced contents of hyp.mbn with U-Boot, which gave > me access to EL2 and I was able to boot Xen and then Linux as Dom0. Yeah we're talking about the same thing. I was just curious whether the Chrome folks have heard of it, or whether they have any changes/ workarounds for it. Konrad
