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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v3 04/11] optee: add OP-TEE mediator skeleton
From: Volodymyr Babchuk <vlad.babchuk@xxxxxxxxx>
Add very basic OP-TEE mediator. It can probe for OP-TEE presence,
tell it about domain creation/destruction and forward all known
calls.
This is all what is needed for Dom0 to work with OP-TEE as long
as Dom0 shares 1:1 mapped pages with OP-TEE. Any attempt to call
OP-TEE from DomU will fail and can lead to spectacular results. Also,
problems can arise if Dom0 uses pages mapped from other domains.
So, this patch should not be merged without next patches in the series.
This code issues two non-preemptible calls to OP-TEE: to create and
to destroy client context. They can't block in OP-TEE, but OP-TEE can
wait on a splinlocks, so there is no maximal execution time
guaranteed.
Signed-off-by: Volodymyr Babchuk <vlad.babchuk@xxxxxxxxx>
---
Changes from v2:
- Fixed coding style
- Introduced tee/Kconfig
- Fixed error messages
xen/arch/arm/Kconfig | 2 +
xen/arch/arm/tee/Kconfig | 4 +
xen/arch/arm/tee/Makefile | 1 +
xen/arch/arm/tee/optee.c | 151 ++++++++++++++++++++++++++++
xen/include/asm-arm/tee/optee_smc.h | 50 +++++++++
5 files changed, 208 insertions(+)
create mode 100644 xen/arch/arm/tee/Kconfig
create mode 100644 xen/arch/arm/tee/optee.c
diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig
index e527b2f885..99e6f0ebb2 100644
--- a/xen/arch/arm/Kconfig
+++ b/xen/arch/arm/Kconfig
@@ -237,3 +237,5 @@ source "arch/arm/platforms/Kconfig"
source "common/Kconfig"
source "drivers/Kconfig"
+
+source "arch/arm/tee/Kconfig"
diff --git a/xen/arch/arm/tee/Kconfig b/xen/arch/arm/tee/Kconfig
new file mode 100644
index 0000000000..5b829db2e9
--- /dev/null
+++ b/xen/arch/arm/tee/Kconfig
@@ -0,0 +1,4 @@
+config OPTEE
+ bool "Enable OP-TEE mediator"
+ default n
+ depends on TEE
diff --git a/xen/arch/arm/tee/Makefile b/xen/arch/arm/tee/Makefile
index c54d4796ff..982c879684 100644
--- a/xen/arch/arm/tee/Makefile
+++ b/xen/arch/arm/tee/Makefile
@@ -1 +1,2 @@
obj-y += tee.o
+obj-$(CONFIG_OPTEE) += optee.o
diff --git a/xen/arch/arm/tee/optee.c b/xen/arch/arm/tee/optee.c
new file mode 100644
index 0000000000..73ad25ee0b
--- /dev/null
+++ b/xen/arch/arm/tee/optee.c
@@ -0,0 +1,151 @@
+/*
+ * xen/arch/arm/tee/optee.c
+ *
+ * OP-TEE mediator
+ *
+ * Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>
+ * Copyright (c) 2018 EPAM Systems.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <xen/device_tree.h>
+#include <xen/sched.h>
+#include <asm/smccc.h>
+#include <asm/tee/tee.h>
+
+#include <asm/tee/optee_msg.h>
+#include <asm/tee/optee_smc.h>
+
+/* Client ID 0 is reserved for hypervisor itself */
+#define OPTEE_CLIENT_ID(domain) (domain->domain_id + 1)
+
+static bool optee_probe(void)
+{
+ struct dt_device_node *node;
+ struct arm_smccc_res resp;
+
+ /* Check for entry in dtb */
+ node = dt_find_compatible_node(NULL, NULL, "linaro,optee-tz");
+ if ( !node )
+ return false;
+
+ /* Check UID */
+ arm_smccc_smc(ARM_SMCCC_CALL_UID_FID(TRUSTED_OS_END), &resp);
+
+ if ( (uint32_t)resp.a0 != OPTEE_MSG_UID_0 ||
+ (uint32_t)resp.a1 != OPTEE_MSG_UID_1 ||
+ (uint32_t)resp.a2 != OPTEE_MSG_UID_2 ||
+ (uint32_t)resp.a3 != OPTEE_MSG_UID_3 )
+ return false;
+
+ return true;
+}
+
+static int optee_enable(struct domain *d)
+{
+ struct arm_smccc_res resp;
+
+ /*
+ * Inform OP-TEE about a new guest.
+ * This is a "Fast" call in terms of OP-TEE. This basically
+ * means that it can't be preempted, because there is no
+ * thread allocated for it in OP-TEE. It is close to atomic
+ * context in linux kernel: E.g. no blocking calls can be issued.
+ * Also, interrupts are disabled.
+ * Right now OP-TEE just frees allocated memory, so it should be
+ * really fast.
+ */
+ arm_smccc_smc(OPTEE_SMC_VM_CREATED, OPTEE_CLIENT_ID(d), 0, 0, 0, 0, 0, 0,
+ &resp);
+ if ( resp.a0 != OPTEE_SMC_RETURN_OK )
+ {
+ gprintk(XENLOG_WARNING, "Unable to create OPTEE client: rc = 0x%X\n",
+ (uint32_t)resp.a0);
+ return -ENODEV;
+ }
+
+ return 0;
+}
+
+static void forward_call(struct cpu_user_regs *regs)
+{
+ struct arm_smccc_res resp;
+
+ arm_smccc_smc(get_user_reg(regs, 0),
+ get_user_reg(regs, 1),
+ get_user_reg(regs, 2),
+ get_user_reg(regs, 3),
+ get_user_reg(regs, 4),
+ get_user_reg(regs, 5),
+ get_user_reg(regs, 6),
+ OPTEE_CLIENT_ID(current->domain),
+ &resp);
+
+ set_user_reg(regs, 0, resp.a0);
+ set_user_reg(regs, 1, resp.a1);
+ set_user_reg(regs, 2, resp.a2);
+ set_user_reg(regs, 3, resp.a3);
+ set_user_reg(regs, 4, 0);
+ set_user_reg(regs, 5, 0);
+ set_user_reg(regs, 6, 0);
+ set_user_reg(regs, 7, 0);
+}
+
+static void optee_domain_destroy(struct domain *d)
+{
+ struct arm_smccc_res resp;
+
+ /* At this time all domain VCPUs should be stopped */
+
+ /*
+ * Inform OP-TEE that domain is shutting down. This is
+ * also a fast SMC call, like OPTEE_SMC_VM_CREATED, so
+ * it is also non-preemptible.
+ */
+ arm_smccc_smc(OPTEE_SMC_VM_DESTROYED, OPTEE_CLIENT_ID(d), 0, 0, 0, 0, 0, 0,
+ &resp);
+}
+
+static bool optee_handle_call(struct cpu_user_regs *regs)
+{
+ switch ( get_user_reg(regs, 0) )
+ {
+ case OPTEE_SMC_CALLS_COUNT:
+ case OPTEE_SMC_CALLS_UID:
+ case OPTEE_SMC_CALLS_REVISION:
+ case OPTEE_SMC_CALL_GET_OS_UUID:
+ case OPTEE_SMC_FUNCID_GET_OS_REVISION:
+ case OPTEE_SMC_ENABLE_SHM_CACHE:
+ case OPTEE_SMC_DISABLE_SHM_CACHE:
+ case OPTEE_SMC_GET_SHM_CONFIG:
+ case OPTEE_SMC_EXCHANGE_CAPABILITIES:
+ case OPTEE_SMC_CALL_WITH_ARG:
+ case OPTEE_SMC_CALL_RETURN_FROM_RPC:
+ forward_call(regs);
+ return true;
+ default:
+ return false;
+ }
+}
+
+static const struct tee_mediator_ops optee_ops =
+{
+ .probe = optee_probe,
+ .enable = optee_enable,
+ .domain_destroy = optee_domain_destroy,
+ .handle_call = optee_handle_call,
+};
+
+REGISTER_TEE_MEDIATOR(optee, "OP-TEE", &optee_ops);
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/include/asm-arm/tee/optee_smc.h
b/xen/include/asm-arm/tee/optee_smc.h
index 26d100e215..1c5a2479e9 100644
--- a/xen/include/asm-arm/tee/optee_smc.h
+++ b/xen/include/asm-arm/tee/optee_smc.h
@@ -304,6 +304,56 @@ struct optee_smc_disable_shm_cache_result {
#define OPTEE_SMC_ENABLE_SHM_CACHE \
OPTEE_SMC_FAST_CALL_VAL(OPTEE_SMC_FUNCID_ENABLE_SHM_CACHE)
+/*
+ * Inform OP-TEE about a new virtual machine
+ *
+ * Hypervisor issues this call during virtual machine (guest) creation.
+ * OP-TEE records VM_ID of new virtual machine and makes self ready
+ * to receive requests from it.
+ *
+ * Call requests usage:
+ * a0 SMC Function ID, OPTEE_SMC_VM_CREATED
+ * a1 VM_ID of newly created virtual machine
+ * a2-6 Not used
+ * a7 Hypervisor Client ID register. Must be 0, because only hypervisor
+ * can issue this call
+ *
+ * Normal return register usage:
+ * a0 OPTEE_SMC_RETURN_OK
+ * a1-7 Preserved
+ *
+ * Error return:
+ * a0 OPTEE_SMC_RETURN_ENOTAVAIL OP-TEE has no resources for
+ * another VM
+ * a1-7 Preserved
+ *
+ */
+#define OPTEE_SMC_FUNCID_VM_CREATED 13
+#define OPTEE_SMC_VM_CREATED \
+ OPTEE_SMC_FAST_CALL_VAL(OPTEE_SMC_FUNCID_VM_CREATED)
+
+/*
+ * Inform OP-TEE about shutdown of a virtual machine
+ *
+ * Hypervisor issues this call during virtual machine (guest) destruction.
+ * OP-TEE will clean up all resources associated with this VM.
+ *
+ * Call requests usage:
+ * a0 SMC Function ID, OPTEE_SMC_VM_DESTROYED
+ * a1 VM_ID of virtual machine being shutted down
+ * a2-6 Not used
+ * a7 Hypervisor Client ID register. Must be 0, because only hypervisor
+ * can issue this call
+ *
+ * Normal return register usage:
+ * a0 OPTEE_SMC_RETURN_OK
+ * a1-7 Preserved
+ *
+ */
+#define OPTEE_SMC_FUNCID_VM_DESTROYED 14
+#define OPTEE_SMC_VM_DESTROYED \
+ OPTEE_SMC_FAST_CALL_VAL(OPTEE_SMC_FUNCID_VM_DESTROYED)
+
/*
* Resume from RPC (for example after processing a foreign interrupt)
*
--
2.20.0
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