Re: [PATCH v2] soc: qcom: cmd-db: Map shared memory as WC, not WB

[Pavan Kondeti]

Hi Bjorn,

On Thu, Jul 18, 2024 at 09:41:34AM +0200, Caleb Connolly wrote:
> 
> 
> On 18/07/2024 08:03, Maulik Shah wrote:
> > From: Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>
> > 
> > Linux does not write into cmd-db region. This region of memory is write
> > protected by XPU. XPU may sometime falsely detect clean cache eviction
> > as "write" into the write protected region leading 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.
> > 
> > Changing the mapping of cmd-db memory from MEMREMAP_WB to MEMREMAP_WT/WC
> > removes dependency on correct mappings in Stage 2 tables. This patch
> > fixes the issue by updating the mapping to MEMREMAP_WC.
> > 
> > I tested this on SA8155P with Xen.
> > 
> > Fixes: 312416d9171a ("drivers: qcom: add command DB driver")
> > Cc: stable@xxxxxxxxxxxxxxx # 5.4+
> > Signed-off-by: Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>
> > Tested-by: Nikita Travkin <nikita@xxxxxxx> # sc7180 WoA in EL2
> > Signed-off-by: Maulik Shah <quic_mkshah@xxxxxxxxxxx>
> 
> Reviewed-by: Caleb Connolly <caleb.connolly@xxxxxxxxxx>

Is it possible to include it in v6.11-rc?

Thanks,
Pavan