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Re: [Xen-devel] [PATCH v2 09/15] xen/arm: psci: Detect SMCCC version
On 02/09/2018 05:04 PM, Volodymyr Babchuk wrote:
Julien,
On 08.02.18 21:21, Julien Grall wrote:
PSCI 1.0 and later allows the SMCCC version to be (indirectly) probed
via PSCI_FEATURES. If the PSCI_FEATURES does not exist (PSCI 0.2 or
earlier) and the function return an error, then we considered SMCCC 1.0
is implemented.
Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
---
Changes in v2:
- Patch added
---
xen/arch/arm/psci.c | 34 +++++++++++++++++++++++++++++++++-
xen/include/asm-arm/smccc.h | 5 ++++-
2 files changed, 37 insertions(+), 2 deletions(-)
diff --git a/xen/arch/arm/psci.c b/xen/arch/arm/psci.c
I find it strange to determine SMCCC version in PSCI code. psci.c is not
the first place, where I will look for SMCCC version discovery.
I think it is better to add smccc.c, where such functions can reside.
SMCCC version discovery is based on PSCI, hence it is in the PSCI code.
I can't see a good reason to create a file with 3 lines at the moment.
index 5dda35cd7c..bc7b2260e8 100644
--- a/xen/arch/arm/psci.c
+++ b/xen/arch/arm/psci.c
@@ -37,6 +37,7 @@
#endif
uint32_t psci_ver;
+uint32_t smccc_ver;
And this variable actually is not related to PSCI.
See my comment above. I am not going to create a file just for 3 lines.
static uint32_t psci_cpu_on_nr;
@@ -57,6 +58,14 @@ void call_psci_system_reset(void)
call_smc(PSCI_0_2_FN32_SYSTEM_RESET, 0, 0, 0);
}
+static int __init psci_features(uint32_t psci_func_id)
+{
+ if ( psci_ver < PSCI_VERSION(1, 0) )
+ return PSCI_NOT_SUPPORTED;
+
+ return call_smc(PSCI_1_0_FN32_PSCI_FEATURES, psci_func_id, 0, 0);
+}
+
int __init psci_is_smc_method(const struct dt_device_node *psci)
{
int ret;
@@ -82,6 +91,24 @@ int __init psci_is_smc_method(const struct
dt_device_node *psci)
return 0;
}
+static void __init psci_init_smccc(void)
+{
+ /* PSCI is using at least SMCC 1.0 calling convention. */
+ smccc_ver = ARM_SMCCC_VERSION_1_0;
+
+ if ( psci_features(ARM_SMCCC_VERSION_FID) != PSCI_NOT_SUPPORTED )
+ {
+ uint32_t ret;
+
+ ret = call_smc(ARM_SMCCC_VERSION_FID, 0, 0, 0);
+ if ( ret != ARM_SMCCC_NOT_SUPPORTED )
+ smccc_ver = ret;
+ }
+
+ printk(XENLOG_INFO "Using SMC Calling Convention v%u.%u\n",
+ SMCCC_VERSION_MAJOR(smccc_ver),
SMCCC_VERSION_MINOR(smccc_ver));
+}
+
int __init psci_init_0_1(void)
{
int ret;
@@ -173,7 +200,12 @@ int __init psci_init(void)
if ( ret )
ret = psci_init_0_1();
- return ret;
+ if ( ret )
+ return ret;
+
+ psci_init_smccc();
+
+ return 0;
}
/*
diff --git a/xen/include/asm-arm/smccc.h b/xen/include/asm-arm/smccc.h
index caa2c9cc1b..bc067892c7 100644
--- a/xen/include/asm-arm/smccc.h
+++ b/xen/include/asm-arm/smccc.h
@@ -52,6 +52,8 @@
#ifndef __ASSEMBLY__
+extern uint32_t smccc_ver;
+
/* Check if this is fast call. */
static inline bool smccc_is_fast_call(register_t funcid)
{
@@ -137,8 +139,9 @@ static inline uint32_t smccc_get_owner(register_t
funcid)
ARM_SMCCC_OWNER_ARCH, \
0x8000)
-/* Only one error code defined in SMCCC */
+/* SMCCC error codes */
#define ARM_SMCCC_ERR_UNKNOWN_FUNCTION (-1)
+#define ARM_SMCCC_NOT_SUPPORTED (-1)
In patch "xen/arm: vsmc: Implement SMCCC 1.1" you return plain -1 in
static bool handle_arch(struct cpu_user_regs *regs)
Could you please move definition of ARM_SMCCC_NOT_SUPPORTED into that
patch and use it in mentioned function or add new patch that changes -1
to ARM_SMCCC_NOT_SUPPORTED ?
Will do.
/* SMCCC function identifier range which is reserved for existing
APIs */
#define ARM_SMCCC_RESERVED_RANGE_START 0x0
Cheers,
--
Julien Grall
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