[PATCH 4.14 089/195] [Variant 2/Spectre-v2] firmware/psci: Expose PSCI conduit

[Greg Kroah-Hartman]

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Marc Zyngier <marc.zyngier@xxxxxxx>


Commit 09a8d6d48499 upstream.

In order to call into the firmware to apply workarounds, it is
useful to find out whether we're using HVC or SMC. Let's expose
this through the psci_ops.

Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
Reviewed-by: Robin Murphy <robin.murphy@xxxxxxx>
Tested-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/firmware/psci.c |   28 +++++++++++++++++++++++-----
 include/linux/psci.h    |    7 +++++++
 2 files changed, 30 insertions(+), 5 deletions(-)

--- a/drivers/firmware/psci.c
+++ b/drivers/firmware/psci.c
@@ -59,7 +59,9 @@ bool psci_tos_resident_on(int cpu)
 	return cpu == resident_cpu;
 }
 
-struct psci_operations psci_ops;
+struct psci_operations psci_ops = {
+	.conduit = PSCI_CONDUIT_NONE,
+};
 
 typedef unsigned long (psci_fn)(unsigned long, unsigned long,
 				unsigned long, unsigned long);
@@ -210,6 +212,22 @@ static unsigned long psci_migrate_info_u
 			      0, 0, 0);
 }
 
+static void set_conduit(enum psci_conduit conduit)
+{
+	switch (conduit) {
+	case PSCI_CONDUIT_HVC:
+		invoke_psci_fn = __invoke_psci_fn_hvc;
+		break;
+	case PSCI_CONDUIT_SMC:
+		invoke_psci_fn = __invoke_psci_fn_smc;
+		break;
+	default:
+		WARN(1, "Unexpected PSCI conduit %d\n", conduit);
+	}
+
+	psci_ops.conduit = conduit;
+}
+
 static int get_set_conduit_method(struct device_node *np)
 {
 	const char *method;
@@ -222,9 +240,9 @@ static int get_set_conduit_method(struct
 	}
 
 	if (!strcmp("hvc", method)) {
-		invoke_psci_fn = __invoke_psci_fn_hvc;
+		set_conduit(PSCI_CONDUIT_HVC);
 	} else if (!strcmp("smc", method)) {
-		invoke_psci_fn = __invoke_psci_fn_smc;
+		set_conduit(PSCI_CONDUIT_SMC);
 	} else {
 		pr_warn("invalid \"method\" property: %s\n", method);
 		return -EINVAL;
@@ -654,9 +672,9 @@ int __init psci_acpi_init(void)
 	pr_info("probing for conduit method from ACPI.\n");
 
 	if (acpi_psci_use_hvc())
-		invoke_psci_fn = __invoke_psci_fn_hvc;
+		set_conduit(PSCI_CONDUIT_HVC);
 	else
-		invoke_psci_fn = __invoke_psci_fn_smc;
+		set_conduit(PSCI_CONDUIT_SMC);
 
 	return psci_probe();
 }
--- a/include/linux/psci.h
+++ b/include/linux/psci.h
@@ -25,6 +25,12 @@ bool psci_tos_resident_on(int cpu);
 int psci_cpu_init_idle(unsigned int cpu);
 int psci_cpu_suspend_enter(unsigned long index);
 
+enum psci_conduit {
+	PSCI_CONDUIT_NONE,
+	PSCI_CONDUIT_SMC,
+	PSCI_CONDUIT_HVC,
+};
+
 struct psci_operations {
 	u32 (*get_version)(void);
 	int (*cpu_suspend)(u32 state, unsigned long entry_point);
@@ -34,6 +40,7 @@ struct psci_operations {
 	int (*affinity_info)(unsigned long target_affinity,
 			unsigned long lowest_affinity_level);
 	int (*migrate_info_type)(void);
+	enum psci_conduit conduit;
 };
 
 extern struct psci_operations psci_ops;