5.4-stable review patch. If anyone has any objections, please let me know.
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From: Volodymyr Babchuk Volodymyr_Babchuk@epam.com
commit f9bb896eab221618927ae6a2f1d566567999839d upstream.
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@vger.kernel.org # 5.4+ Signed-off-by: Volodymyr Babchuk volodymyr_babchuk@epam.com Tested-by: Nikita Travkin nikita@trvn.ru # sc7180 WoA in EL2 Signed-off-by: Maulik Shah quic_mkshah@quicinc.com Tested-by: Pavankumar Kondeti quic_pkondeti@quicinc.com Reviewed-by: Caleb Connolly caleb.connolly@linaro.org Link: https://lore.kernel.org/r/20240718-cmd_db_uncached-v2-1-f6cf53164c90@quicinc... Signed-off-by: Bjorn Andersson andersson@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/soc/qcom/cmd-db.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/soc/qcom/cmd-db.c +++ b/drivers/soc/qcom/cmd-db.c @@ -247,7 +247,7 @@ static int cmd_db_dev_probe(struct platf return -EINVAL; }
- cmd_db_header = memremap(rmem->base, rmem->size, MEMREMAP_WB); + cmd_db_header = memremap(rmem->base, rmem->size, MEMREMAP_WC); if (!cmd_db_header) { ret = -ENOMEM; cmd_db_header = NULL;