[RFC PATCH v2 42/58] iommu/arm-smmu-v3-kvm: Add host driver for pKVM

[Mostafa Saleh <smostafa@google.com>]

From: Jean-Philippe Brucker <jean-philippe@linaro.org>

Under protected KVM (pKVM), the host does not have access to guest or
hypervisor memory. This means that devices owned by the host must be
isolated by the SMMU, and the hypervisor is in charge of the SMMU.

Introduce the host component that replaces the normal SMMUv3 driver when
pKVM is enabled, and sends configuration and requests to the actual
driver running in the hypervisor (EL2).

Rather than rely on regular driver probe, pKVM directly calls
kvm_arm_smmu_v3_init(), which synchronously finds all SMMUs and hands
them to the hypervisor. If the regular driver is enabled, it will not
find any free SMMU to drive once it gets probed.

Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Signed-off-by: Mostafa Saleh <smostafa@google.com>
---
 drivers/iommu/arm/arm-smmu-v3/Makefile        |  6 ++
 .../iommu/arm/arm-smmu-v3/arm-smmu-v3-kvm.c   | 64 +++++++++++++++++++
 2 files changed, 70 insertions(+)
 create mode 100644 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-kvm.c

diff --git a/drivers/iommu/arm/arm-smmu-v3/Makefile b/drivers/iommu/arm/arm-smmu-v3/Makefile
index 515a84f14783..7a182adbebc1 100644
--- a/drivers/iommu/arm/arm-smmu-v3/Makefile
+++ b/drivers/iommu/arm/arm-smmu-v3/Makefile
@@ -6,3 +6,9 @@ arm_smmu_v3-$(CONFIG_ARM_SMMU_V3_SVA) += arm-smmu-v3-sva.o
 arm_smmu_v3-$(CONFIG_TEGRA241_CMDQV) += tegra241-cmdqv.o
 
 obj-$(CONFIG_ARM_SMMU_V3_KUNIT_TEST) += arm-smmu-v3-test.o
+
+obj-$(CONFIG_ARM_SMMU_V3_PKVM) += arm_smmu_v3_kvm.o
+ccflags-$(CONFIG_ARM_SMMU_V3_PKVM) += -Iarch/arm64/kvm/
+arm_smmu_v3_kvm-objs-y += arm-smmu-v3-kvm.o
+arm_smmu_v3_kvm-objs-y += arm-smmu-v3-common.o
+arm_smmu_v3_kvm-objs := $(arm_smmu_v3_kvm-objs-y)
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-kvm.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-kvm.c
new file mode 100644
index 000000000000..8cea33d15e08
--- /dev/null
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-kvm.c
@@ -0,0 +1,64 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * pKVM host driver for the Arm SMMUv3
+ *
+ * Copyright (C) 2022 Linaro Ltd.
+ */
+#include <asm/kvm_mmu.h>
+
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+
+#include <kvm/arm_smmu_v3.h>
+
+#include "arm-smmu-v3.h"
+
+extern struct kvm_iommu_ops kvm_nvhe_sym(smmu_ops);
+
+static int kvm_arm_smmu_probe(struct platform_device *pdev)
+{
+	return -ENOSYS;
+}
+
+static void kvm_arm_smmu_remove(struct platform_device *pdev)
+{
+}
+
+static const struct of_device_id arm_smmu_of_match[] = {
+	{ .compatible = "arm,smmu-v3", },
+	{ },
+};
+
+static struct platform_driver kvm_arm_smmu_driver = {
+	.driver = {
+		.name = "kvm-arm-smmu-v3",
+		.of_match_table = arm_smmu_of_match,
+	},
+	.remove = kvm_arm_smmu_remove,
+};
+
+static int kvm_arm_smmu_v3_init_drv(void)
+{
+	return platform_driver_probe(&kvm_arm_smmu_driver, kvm_arm_smmu_probe);
+}
+
+static void kvm_arm_smmu_v3_remove_drv(void)
+{
+	platform_driver_unregister(&kvm_arm_smmu_driver);
+}
+
+struct kvm_iommu_driver kvm_smmu_v3_ops = {
+	.init_driver = kvm_arm_smmu_v3_init_drv,
+	.remove_driver = kvm_arm_smmu_v3_remove_drv,
+};
+
+static int kvm_arm_smmu_v3_register(void)
+{
+	if (!is_protected_kvm_enabled())
+		return 0;
+
+	return kvm_iommu_register_driver(&kvm_smmu_v3_ops,
+					kern_hyp_va(lm_alias(&kvm_nvhe_sym(smmu_ops))));
+};
+
+core_initcall(kvm_arm_smmu_v3_register);
-- 
2.47.0.338.g60cca15819-goog