ANDROID: KVM: arm64: Introduce IOMMU driver infrastructure

Bootstrap infrastructure for IOMMU drivers by introducing kvm_iommu_ops
struct in EL2 that is populated based on a iommu_driver parameter to
__pkvm_init hypercall and selected in EL1 early init.

An 'init' operation is called in __pkvm_init_finalise, giving the driver
an opportunity to initialize itself in EL2 and create any EL2 mappings
that it will need. 'init' is specifically called before
'finalize_host_mappings' so that:
  (a) pages mapped by the driver change owner to hyp,
  (b) ownership changes in 'finalize_host_mappings' get reflected in
      IOMMU mappings (added in a future patch).

Test: builds, boots
Bug: 190463801
Signed-off-by: David Brazdil <dbrazdil@google.com>
Change-Id: Icd496d193c0bbf811406c3a8d4b94610e2a03197

arch/arm64/include/asm/kvm_host.h

@@ -271,6 +271,10 @@ extern s64 kvm_nvhe_sym(hyp_physvirt_offset);
 extern u64 kvm_nvhe_sym(hyp_cpu_logical_map)[NR_CPUS];
 #define hyp_cpu_logical_map CHOOSE_NVHE_SYM(hyp_cpu_logical_map)
 
+enum kvm_iommu_driver {
+	KVM_IOMMU_DRIVER_NONE,
+};
+
 struct vcpu_reset_state {
 	unsigned long	pc;
 	unsigned long	r0;

arch/arm64/include/asm/kvm_hyp.h

@@ -110,7 +110,8 @@ void __noreturn __hyp_do_panic(struct kvm_cpu_context *host_ctxt, u64 spsr,
 void __pkvm_init_switch_pgd(phys_addr_t phys, unsigned long size,
 			    phys_addr_t pgd, void *sp, void *cont_fn);
 int __pkvm_init(phys_addr_t phys, unsigned long size, unsigned long nr_cpus,
-		unsigned long *per_cpu_base, u32 hyp_va_bits);
+		unsigned long *per_cpu_base, u32 hyp_va_bits,
+		enum kvm_iommu_driver iommu_driver);
 void __noreturn __host_enter(struct kvm_cpu_context *host_ctxt);
 #endif
 
@@ -122,4 +123,10 @@ extern u64 kvm_nvhe_sym(id_aa64mmfr0_el1_sys_val);
 extern u64 kvm_nvhe_sym(id_aa64mmfr1_el1_sys_val);
 extern u64 kvm_nvhe_sym(id_aa64mmfr2_el1_sys_val);
 
+struct kvm_iommu_ops {
+	int (*init)(void);
+};
+
+extern struct kvm_iommu_ops kvm_iommu_ops;
+
 #endif /* __ARM64_KVM_HYP_H__ */

arch/arm64/kvm/arm.c

@@ -1755,6 +1755,11 @@ static bool init_psci_relay(void)
 	return true;
 }
 
+static int init_stage2_iommu(void)
+{
+	return KVM_IOMMU_DRIVER_NONE;
+}
+
 static int init_subsystems(void)
 {
 	int err = 0;
@@ -1814,7 +1819,7 @@ static void teardown_hyp_mode(void)
 	}
 }
 
-static int do_pkvm_init(u32 hyp_va_bits)
+static int do_pkvm_init(u32 hyp_va_bits, enum kvm_iommu_driver iommu_driver)
 {
 	void *per_cpu_base = kvm_ksym_ref(kvm_arm_hyp_percpu_base);
 	int ret;
@@ -1823,7 +1828,7 @@ static int do_pkvm_init(u32 hyp_va_bits)
 	cpu_hyp_init_context();
 	ret = kvm_call_hyp_nvhe(__pkvm_init, hyp_mem_base, hyp_mem_size,
 				num_possible_cpus(), kern_hyp_va(per_cpu_base),
-				hyp_va_bits);
+				hyp_va_bits, iommu_driver);
 	cpu_hyp_init_features();
 
 	/*
@@ -1853,7 +1858,11 @@ static int kvm_hyp_init_protection(u32 hyp_va_bits)
 	if (ret)
 		return ret;
 
-	ret = do_pkvm_init(hyp_va_bits);
+	ret = init_stage2_iommu();
+	if (ret < 0)
+		return ret;
+
+	ret = do_pkvm_init(hyp_va_bits, (enum kvm_iommu_driver)ret);
 	if (ret)
 		return ret;
 

arch/arm64/kvm/hyp/nvhe/hyp-main.c

@@ -19,6 +19,8 @@
 
 DEFINE_PER_CPU(struct kvm_nvhe_init_params, kvm_init_params);
 
+struct kvm_iommu_ops kvm_iommu_ops;
+
 void __kvm_hyp_host_forward_smc(struct kvm_cpu_context *host_ctxt);
 
 static void handle___kvm_vcpu_run(struct kvm_cpu_context *host_ctxt)
@@ -123,6 +125,7 @@ static void handle___pkvm_init(struct kvm_cpu_context *host_ctxt)
 	DECLARE_REG(unsigned long, nr_cpus, host_ctxt, 3);
 	DECLARE_REG(unsigned long *, per_cpu_base, host_ctxt, 4);
 	DECLARE_REG(u32, hyp_va_bits, host_ctxt, 5);
+	DECLARE_REG(enum kvm_iommu_driver, iommu_driver, host_ctxt, 6);
 
 	/*
 	 * __pkvm_init() will return only if an error occurred, otherwise it
@@ -130,7 +133,7 @@ static void handle___pkvm_init(struct kvm_cpu_context *host_ctxt)
 	 * with the host context directly.
 	 */
 	cpu_reg(host_ctxt, 1) = __pkvm_init(phys, size, nr_cpus, per_cpu_base,
-					    hyp_va_bits);
+					    hyp_va_bits, iommu_driver);
 }
 
 static void handle___pkvm_cpu_set_vector(struct kvm_cpu_context *host_ctxt)

arch/arm64/kvm/hyp/nvhe/setup.c

@@ -233,6 +233,16 @@ static int finalize_host_mappings(void)
 	return 0;
 }
 
+int select_iommu_ops(enum kvm_iommu_driver driver)
+{
+	switch (driver) {
+	case KVM_IOMMU_DRIVER_NONE:
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
 void __noreturn __pkvm_init_finalise(void)
 {
 	struct kvm_host_data *host_data = this_cpu_ptr(&kvm_host_data);
@@ -252,6 +262,12 @@ void __noreturn __pkvm_init_finalise(void)
 	if (ret)
 		goto out;
 
+	if (kvm_iommu_ops.init) {
+		ret = kvm_iommu_ops.init();
+		if (ret)
+			goto out;
+	}
+
 	pkvm_pgtable_mm_ops = (struct kvm_pgtable_mm_ops) {
 		.zalloc_page = hyp_zalloc_hyp_page,
 		.phys_to_virt = hyp_phys_to_virt,
@@ -277,7 +293,8 @@ out:
 }
 
 int __pkvm_init(phys_addr_t phys, unsigned long size, unsigned long nr_cpus,
-		unsigned long *per_cpu_base, u32 hyp_va_bits)
+		unsigned long *per_cpu_base, u32 hyp_va_bits,
+		enum kvm_iommu_driver iommu_driver)
 {
 	struct kvm_nvhe_init_params *params;
 	void *virt = hyp_phys_to_virt(phys);
@@ -300,6 +317,10 @@ int __pkvm_init(phys_addr_t phys, unsigned long size, unsigned long nr_cpus,
 	if (ret)
 		return ret;
 
+	ret = select_iommu_ops(iommu_driver);
+	if (ret)
+		return ret;
+
 	update_nvhe_init_params();
 
 	/* Jump in the idmap page to switch to the new page-tables */