Re: [PATCH v1 09/11] soc: qcom: add ICE keyslot partitioning driver for guest VMs

From: linlzhan <redacted>

On Qualcomm platforms the ICE hardware has a fixed number of physical
keyslots shared across the host and all guest VMs.  A userspace
virtio-blk backend handling VIRTIO_BLK_T_CRYPTO_IN/OUT requests needs
to translate a guest's virtual keyslot index to the corresponding
physical ICE keyslot without letting one VM access another VM's slots.

Add QCOM_ICE_SLOTS, a platform driver that implements bcp_slot_virt_ops
for the /dev/blk-crypto-proxy device.  It parses a
qcom,ice-keyslot-map device-tree node describing the per-VM keyslot
allocation table, where each child entry maps a guest_id to a
contiguous physical slot range [slot_offset .. slot_offset +
max_ice_slots).  Entry 0 is reserved for the host; guest entries start
at index 1 and are excluded from the guest-facing translation so that
blk-crypto-proxy cannot accidentally route a guest request into the
host's physical keyslots.

The driver exposes two callbacks:

  get_guest_slots()  — return the number of ICE keyslots allocated to
                       a given guest_id; used by BCP_GET_CRYPTO_CAPS to
                       populate the max_slots field in the virtio config
                       space.
  vslot_to_pslot()   — translate a (guest_id, virtual-slot) pair to the
                       corresponding physical ICE keyslot index; used by
                       BCP_SUBMIT_IO_BY_VSLOT before calling
                       bio_crypt_set_ctx_by_slot().

The singleton pointer to the parsed table is RCU-protected; the hot
path reads it lock-free.  Probe validates that no two VM entries share
a guest_id or overlapping physical slot ranges.

Note: This patch is submitted for visibility. The keyslot partitioning
is based on the current DT-based keyslot allocation with vm_id known.
We are aware this may be revised to use a TZ SCM query interface in a
future version of this series, submit it RFC for design discussion.

Signed-off-by: linlzhan <redacted>
---
 drivers/soc/qcom/Kconfig          |  18 +++
 drivers/soc/qcom/Makefile         |   1 +
 drivers/soc/qcom/qcom_ice_slots.c | 232 ++++++++++++++++++++++++++++++
 3 files changed, 251 insertions(+)
 create mode 100644 drivers/soc/qcom/qcom_ice_slots.c

diff --git a/drivers/soc/qcom/Kconfig b/drivers/soc/qcom/Kconfig
index 6c632d114d45..e1f383b4dc63 100644
--- a/drivers/soc/qcom/Kconfig
+++ b/drivers/soc/qcom/Kconfig

@@ -294,6 +294,24 @@ endif
 # Options selected by other drivers from different subsystems must be outside
 # of the menuconfig if-block:
 
+config QCOM_ICE_SLOTS
+	tristate "Qualcomm ICE keyslot partitioning for VM guests"
+	depends on ARCH_QCOM || COMPILE_TEST
+	depends on BLK_CRYPTO_PROXY
+	depends on BLK_INLINE_ENCRYPTION
+	help
+	  Parses the qcom,ice-keyslot-map device-tree node and provides
+	  per-VM ICE keyslot accounting and virtual-to-physical slot
+	  translation for guest VMs sharing ICE hardware on Qualcomm
+	  platforms.
+
+	  When enabled, guest virtual keyslot indices are mapped to the
+	  physical ICE keyslot range allocated to each VM, preventing one
+	  VM from accessing another VM's keyslots.
+
+	  Say M here when multiple VMs share ICE keyslots on a Qualcomm
+	  platform.  If unsure, say N.
+
 config QCOM_INLINE_CRYPTO_ENGINE
 	tristate
 	select QCOM_SCM

diff --git a/drivers/soc/qcom/Makefile b/drivers/soc/qcom/Makefile
index 6d4b7546d1fb..952a57554f9d 100644
--- a/drivers/soc/qcom/Makefile
+++ b/drivers/soc/qcom/Makefile

@@ -38,6 +38,7 @@ obj-$(CONFIG_QCOM_LLCC) += llcc-qcom.o
 obj-$(CONFIG_QCOM_KRYO_L2_ACCESSORS) +=	kryo-l2-accessors.o
 obj-$(CONFIG_QCOM_ICC_BWMON)	+= icc-bwmon.o
 qcom_ice-objs			+= ice.o
+obj-$(CONFIG_QCOM_ICE_SLOTS)	+= qcom_ice_slots.o
 obj-$(CONFIG_QCOM_INLINE_CRYPTO_ENGINE)	+= qcom_ice.o
 obj-$(CONFIG_QCOM_CRYPTO_VIRT)	+= crypto_virt.o
 obj-$(CONFIG_QCOM_PBS) +=	qcom-pbs.o

diff --git a/drivers/soc/qcom/qcom_ice_slots.c b/drivers/soc/qcom/qcom_ice_slots.c
new file mode 100644
index 000000000000..364ac93077c1
--- /dev/null
+++ b/drivers/soc/qcom/qcom_ice_slots.c

@@ -0,0 +1,232 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * qcom_ice_slots.c - Qualcomm ICE keyslot partitioning for guest VMs
+ *
+ * Implements bcp_slot_virt_ops: translates a (guest_id, virtual-slot) pair to
+ * a physical ICE keyslot index using a per-VM allocation table parsed from
+ * the device-tree node with compatible = "qcom,ice-keyslot-map".
+ *
+ * Device-tree layout:
+ *
+ *   ice_keyslot_map: ice-keyslot-map {
+ *       compatible = "qcom,ice-keyslot-map";

+
+	dev_info(dev, "registered: %u VMs, %u total ICE slots\n",
+		 idx, total_slots);