[RFC PATCH 01/26] psci: Export configured PSCI version

From: David Brazdil <dbrazdil@google.com>
To: kvmarm@lists.cs.columbia.edu
Cc: Mark Rutland <mark.rutland@arm.com>,
	Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	kernel-team@android.com,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Marc Zyngier <maz@kernel.org>,
	Quentin Perret <qperret@google.com>,
	linux-kernel@vger.kernel.org, James Morse <james.morse@arm.com>,
	linux-arm-kernel@lists.infradead.org,
	Catalin Marinas <catalin.marinas@arm.com>,
	Tejun Heo <tj@kernel.org>, Dennis Zhou <dennis@kernel.org>,
	Christoph Lameter <cl@linux.com>,
	David Brazdil <dbrazdil@google.com>,
	Will Deacon <will@kernel.org>,
	Julien Thierry <julien.thierry.kdev@gmail.com>,
	Andrew Scull <ascull@google.com>
Subject: [RFC PATCH 01/26] psci: Export configured PSCI version
Date: Wed,  4 Nov 2020 18:36:05 +0000	[thread overview]
Message-ID: <20201104183630.27513-2-dbrazdil@google.com> (raw)
In-Reply-To: <20201104183630.27513-1-dbrazdil@google.com>

The version of PSCI that the kernel should use to communicate with
firmware is typically obtained from probing PSCI_VERSION. However, that
doesn't work for PSCI v0.1 where the host gets the information from
DT/ACPI, or if PSCI is not supported / was disabled.

KVM's PSCI proxy for the host needs to be configured with the same
version used by the host driver. Expose the PSCI version used by the
host.

Signed-off-by: David Brazdil <dbrazdil@google.com>
---
 drivers/firmware/psci/psci.c | 6 ++++++
 include/linux/psci.h         | 8 ++++++++
 2 files changed, 14 insertions(+)

diff --git a/drivers/firmware/psci/psci.c b/drivers/firmware/psci/psci.c
index 00af99b6f97c..ff523bdbfe3f 100644
--- a/drivers/firmware/psci/psci.c
+++ b/drivers/firmware/psci/psci.c
@@ -49,6 +49,8 @@ static int resident_cpu = -1;
 struct psci_operations psci_ops;
 static enum arm_smccc_conduit psci_conduit = SMCCC_CONDUIT_NONE;
 
+int psci_driver_version = PSCI_VERSION(0, 0);
+
 bool psci_tos_resident_on(int cpu)
 {
 	return cpu == resident_cpu;
@@ -461,6 +463,8 @@ static int __init psci_probe(void)
 		return -EINVAL;
 	}
 
+	psci_driver_version = ver;
+
 	psci_0_2_set_functions();
 
 	psci_init_migrate();
@@ -514,6 +518,8 @@ static int __init psci_0_1_init(struct device_node *np)
 
 	pr_info("Using PSCI v0.1 Function IDs from DT\n");
 
+	psci_driver_version = PSCI_VERSION(0, 1);
+
 	if (!of_property_read_u32(np, "cpu_suspend", &id)) {
 		psci_function_id[PSCI_FN_CPU_SUSPEND] = id;
 		psci_ops.cpu_suspend = psci_cpu_suspend;
diff --git a/include/linux/psci.h b/include/linux/psci.h
index 2a1bfb890e58..cb35b90d1746 100644
--- a/include/linux/psci.h
+++ b/include/linux/psci.h
@@ -21,6 +21,14 @@ bool psci_power_state_is_valid(u32 state);
 int psci_set_osi_mode(bool enable);
 bool psci_has_osi_support(void);
 
+/**
+ * The version of the PSCI specification followed by the driver.
+ * This is equivalent to calling PSCI_VERSION except:
+ *   (a) it also works for PSCI v0.1, which does not support PSCI_VERSION, and
+ *   (b) it is set to v0.0 if the PSCI driver was not initialized.
+ */
+extern int psci_driver_version;
+
 struct psci_operations {
 	u32 (*get_version)(void);
 	int (*cpu_suspend)(u32 state, unsigned long entry_point);
-- 
2.29.1.341.ge80a0c044ae-goog


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