On Thu, Mar 28, 2024 at 04:12:11PM +0500, Nikita Travkin wrote: > On Wed, Mar 27, 2024 at 08:09:34PM +0000, 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. > > > > Hi! > > I observe a similar issue while trying to boot Linux in EL2 after taking > over qcom's hyp on a sc7180 WoA device: > > [ 0.337736] CPU: All CPU(s) started at EL2 > (...) > [ 0.475135] Serial: AMBA PL011 UART driver > [ 0.479649] Internal error: synchronous external abort: 0000000096000410 [#1] PREEMPT SMP > [ 0.488053] Modules linked in: > [ 0.491213] CPU: 6 PID: 1 Comm: swapper/0 Not tainted 6.7.0 #41 > [ 0.497310] Hardware name: Acer Aspire 1 (DT) > [ 0.501800] pstate: 00400009 (nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) > [ 0.508964] pc : cmd_db_dev_probe+0x38/0xc4 > [ 0.513290] lr : cmd_db_dev_probe+0x2c/0xc4 > [ 0.517606] sp : ffff8000817ebab0 > [ 0.521019] x29: ffff8000817ebab0 x28: 0000000000000000 x27: ffff800081346050 > <uart cuts out> > > Unfortunately this patch doesn't help in this case (I beileve I even > tried same/similar change a while back when trying to debug this) > I'm sorry, it looks like I made a mistake in my tooling while testing this patch, which I only realized after trying Maulik's suggestion... Both _WT and _WC fix the issue I see on sc7180 WoA, so whether you keep the patch as is or change it to _WC as suggested: Tested-By: Nikita Travkin <nikita@xxxxxxx> # sc7180 WoA in EL2 Thanks for looking into this! Nikita > Currently I can work around this by just reocationg the cmd-db while > still under the qcom's hyp [1] but it would be nice to find a generic > solution that doesn't need pre-boot hacks... > > AFAIK this is not observed on at least sc8280xp WoA devices and I'd > assume cros is not affected because they don't use qcom's TZ and instead > use TF-A (which is overall more friendly, though still uses qcom's > proprietary qtiseclib under the hood) > > Nikita > > [1] https://github.com/TravMurav/slbounce/blob/main/src/dtbhack_main.c#L17 > > > Signed-off-by: Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx> > > --- > > drivers/soc/qcom/cmd-db.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/soc/qcom/cmd-db.c b/drivers/soc/qcom/cmd-db.c > > index a5fd68411bed5..dd5ababdb476c 100644 > > --- a/drivers/soc/qcom/cmd-db.c > > +++ b/drivers/soc/qcom/cmd-db.c > > @@ -324,7 +324,7 @@ static int cmd_db_dev_probe(struct platform_device *pdev) > > return -EINVAL; > > } > > > > - cmd_db_header = memremap(rmem->base, rmem->size, MEMREMAP_WB); > > + cmd_db_header = memremap(rmem->base, rmem->size, MEMREMAP_WT); > > if (!cmd_db_header) { > > ret = -ENOMEM; > > cmd_db_header = NULL; > > -- > > 2.43.0
