ANDROID: KVM: arm64: devices: Add request_mmio guest HVC

request_mmio is a guest HVC that is used to authenticate a device
MMIO resource, it returns a unique token, that can be used by the
guest.

Bug: 357781595
Bug: 348382247
Change-Id: I87d67ce9c14578702dda1b157411fdc622327286
Signed-off-by: Mostafa Saleh <smostafa@google.com>

arch/arm64/kvm/hyp/include/nvhe/mem_protect.h

@@ -74,6 +74,8 @@ u64 __pkvm_ptdump_walk_range(pkvm_handle_t handle, struct pkvm_ptdump_log_hdr *l
 int hyp_check_range_owned(u64 addr, u64 size);
 int __pkvm_install_guest_mmio(struct pkvm_hyp_vcpu *hyp_vcpu, u64 pfn, u64 gfn);
 
+int __pkvm_guest_get_valid_phys_page(struct pkvm_hyp_vm *vm, u64 *phys, u64 ipa);
+
 bool addr_is_memory(phys_addr_t phys);
 int host_stage2_idmap_locked(phys_addr_t addr, u64 size,
 			     enum kvm_pgtable_prot prot,

arch/arm64/kvm/hyp/include/nvhe/pkvm.h

@@ -162,6 +162,8 @@ int pkvm_host_hvc_pd(u64 device_id, u64 on);
 int pkvm_init_scmi_pd(struct kvm_power_domain *pd,
 		      const struct kvm_power_domain_ops *ops);
 
+bool pkvm_device_request_mmio(struct pkvm_hyp_vcpu *hyp_vcpu, u64 *exit_code);
+
 /*
  * Register a power domain. When the hypervisor catches power requests from the
  * host for this power domain, it calls the power ops with @pd as argument.

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

@@ -7,6 +7,7 @@
 #include <nvhe/mm.h>
 #include <nvhe/pkvm.h>
 
+#include <kvm/arm_hypercalls.h>
 #include <kvm/device.h>
 
 struct pkvm_device *registered_devices;
@@ -234,3 +235,70 @@ out_ret:
 	hyp_spin_unlock(&device_spinlock);
 	return ret;
 }
+
+static int pkvm_get_device_pa(struct pkvm_hyp_vcpu *hyp_vcpu, u64 ipa, u64 *pa, u64 *exit_code)
+{
+	struct kvm_hyp_req *req;
+	int ret;
+	struct pkvm_hyp_vm *vm = pkvm_hyp_vcpu_to_hyp_vm(hyp_vcpu);
+
+	ret = __pkvm_guest_get_valid_phys_page(vm, pa, ipa);
+	if (ret == -ENOENT) {
+		/* Page not mapped, create a request*/
+		req = pkvm_hyp_req_reserve(hyp_vcpu, KVM_HYP_REQ_TYPE_MAP);
+		if (!req)
+			return -ENOMEM;
+
+		req->map.guest_ipa = ipa;
+		req->map.size = PAGE_SIZE;
+		*exit_code = ARM_EXCEPTION_HYP_REQ;
+		/* Repeat next time. */
+		write_sysreg_el2(read_sysreg_el2(SYS_ELR) - 4, SYS_ELR);
+	}
+
+	return ret;
+}
+
+bool pkvm_device_request_mmio(struct pkvm_hyp_vcpu *hyp_vcpu, u64 *exit_code)
+{
+	int i, j, ret;
+	struct kvm_vcpu *vcpu = &hyp_vcpu->vcpu;
+	struct pkvm_hyp_vm *vm = pkvm_hyp_vcpu_to_hyp_vm(hyp_vcpu);
+	u64 ipa = smccc_get_arg1(vcpu);
+	u64 token;
+
+	/* arg2 and arg3 reserved for future use. */
+	if (smccc_get_arg2(vcpu) || smccc_get_arg3(vcpu) || !PAGE_ALIGNED(ipa))
+		goto out_inval;
+
+	ret = pkvm_get_device_pa(hyp_vcpu, ipa, &token, exit_code);
+	if (ret == -ENOENT)
+		return false;
+	else if (ret)
+		goto out_inval;
+
+	hyp_spin_lock(&device_spinlock);
+	for (i = 0 ; i < registered_devices_nr ; ++i) {
+		struct pkvm_device *dev = &registered_devices[i];
+
+		if (dev->ctxt != vm)
+			continue;
+
+		for (j = 0 ; j < dev->nr_resources; ++j) {
+			struct pkvm_dev_resource *res = &dev->resources[j];
+
+			if ((token >= res->base) && (token + PAGE_SIZE <= res->base + res->size)) {
+				smccc_set_retval(vcpu, SMCCC_RET_SUCCESS, token, 0, 0);
+				goto out_ret;
+			}
+		}
+	}
+
+	smccc_set_retval(vcpu, SMCCC_RET_INVALID_PARAMETER, 0, 0, 0);
+out_ret:
+	hyp_spin_unlock(&device_spinlock);
+	return true;
+out_inval:
+	smccc_set_retval(vcpu, SMCCC_RET_INVALID_PARAMETER, 0, 0, 0);
+	return true;
+}

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

@@ -1837,6 +1837,18 @@ static int guest_get_valid_pte(struct pkvm_hyp_vm *vm, u64 *phys, u64 ipa, u8 or
 	return 0;
 }
 
+int __pkvm_guest_get_valid_phys_page(struct pkvm_hyp_vm *vm, u64 *phys, u64 ipa)
+{
+	kvm_pte_t pte;
+	int ret;
+
+	guest_lock_component(vm);
+	ret = guest_get_valid_pte(vm, phys, ipa, 0, &pte);
+	guest_unlock_component(vm);
+
+	return ret;
+}
+
 /*
  * Ideally we would like to use check_unshare()... but this wouldn't let us
  * restrict the unshare range to the actual guest stage-2 mapping.

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

@@ -9,6 +9,7 @@
 
 #include <kvm/arm_hypercalls.h>
 #include <kvm/arm_psci.h>
+#include <kvm/device.h>
 
 #include <asm/kvm_emulate.h>
 
@@ -1659,6 +1660,8 @@ bool kvm_handle_pvm_hvc64(struct kvm_vcpu *vcpu, u64 *exit_code)
 		if (smccc_trng_available)
 			return pkvm_forward_trng(vcpu);
 		break;
+	case ARM_SMCCC_VENDOR_HYP_KVM_DEV_REQ_MMIO_FUNC_ID:
+		return pkvm_device_request_mmio(hyp_vcpu, exit_code);
 	default:
 		return pkvm_handle_psci(hyp_vcpu);
 	}

include/linux/arm-smccc.h

@@ -177,7 +177,7 @@
 #define ARM_SMCCC_KVM_FUNC_PKVM_RESV_60		60
 #define ARM_SMCCC_KVM_FUNC_PKVM_RESV_61		61
 #define ARM_SMCCC_KVM_FUNC_PKVM_RESV_62		62
-#define ARM_SMCCC_KVM_FUNC_PKVM_RESV_63		63
+#define ARM_SMCCC_KVM_FUNC_DEV_REQ_MMIO		63
 /* End of pKVM hypercall range */
 #define ARM_SMCCC_KVM_FUNC_FEATURES_2		127
 #define ARM_SMCCC_KVM_NUM_FUNCS			128
@@ -227,6 +227,12 @@
 			   ARM_SMCCC_OWNER_VENDOR_HYP,			\
 			   ARM_SMCCC_KVM_FUNC_MEM_RELINQUISH)
 
+#define ARM_SMCCC_VENDOR_HYP_KVM_DEV_REQ_MMIO_FUNC_ID			\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,				\
+			   ARM_SMCCC_SMC_64,				\
+			   ARM_SMCCC_OWNER_VENDOR_HYP,			\
+			   ARM_SMCCC_KVM_FUNC_DEV_REQ_MMIO)
+
 /* ptp_kvm counter type ID */
 #define KVM_PTP_VIRT_COUNTER			0
 #define KVM_PTP_PHYS_COUNTER			1