Merge branch kvm-arm64/smccc-filtering into kvmarm-master/next

* kvm-arm64/smccc-filtering:
  : .
  : SMCCC call filtering and forwarding to userspace, courtesy of
  : Oliver Upton. From the cover letter:
  :
  : "The Arm SMCCC is rather prescriptive in regards to the allocation of
  : SMCCC function ID ranges. Many of the hypercall ranges have an
  : associated specification from Arm (FF-A, PSCI, SDEI, etc.) with some
  : room for vendor-specific implementations.
  :
  : The ever-expanding SMCCC surface leaves a lot of work within KVM for
  : providing new features. Furthermore, KVM implements its own
  : vendor-specific ABI, with little room for other implementations (like
  : Hyper-V, for example). Rather than cramming it all into the kernel we
  : should provide a way for userspace to handle hypercalls."
  : .
  KVM: selftests: Fix spelling mistake "KVM_HYPERCAL_EXIT_SMC" -> "KVM_HYPERCALL_EXIT_SMC"
  KVM: arm64: Test that SMC64 arch calls are reserved
  KVM: arm64: Prevent userspace from handling SMC64 arch range
  KVM: arm64: Expose SMC/HVC width to userspace
  KVM: selftests: Add test for SMCCC filter
  KVM: selftests: Add a helper for SMCCC calls with SMC instruction
  KVM: arm64: Let errors from SMCCC emulation to reach userspace
  KVM: arm64: Return NOT_SUPPORTED to guest for unknown PSCI version
  KVM: arm64: Introduce support for userspace SMCCC filtering
  KVM: arm64: Add support for KVM_EXIT_HYPERCALL
  KVM: arm64: Use a maple tree to represent the SMCCC filter
  KVM: arm64: Refactor hvc filtering to support different actions
  KVM: arm64: Start handling SMCs from EL1
  KVM: arm64: Rename SMC/HVC call handler to reflect reality
  KVM: arm64: Add vm fd device attribute accessors
  KVM: arm64: Add a helper to check if a VM has ran once
  KVM: x86: Redefine 'longmode' as a flag for KVM_EXIT_HYPERCALL

Signed-off-by: Marc Zyngier <maz@kernel.org>

4 files changed, 315 insertions, 19 deletions

diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index 84a627c43795..d66a0642cffd 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -141,6 +141,7 @@ TEST_GEN_PROGS_aarch64 += aarch64/get-reg-list
 TEST_GEN_PROGS_aarch64 += aarch64/hypercalls
 TEST_GEN_PROGS_aarch64 += aarch64/page_fault_test
 TEST_GEN_PROGS_aarch64 += aarch64/psci_test
+TEST_GEN_PROGS_aarch64 += aarch64/smccc_filter
 TEST_GEN_PROGS_aarch64 += aarch64/vcpu_width_config
 TEST_GEN_PROGS_aarch64 += aarch64/vgic_init
 TEST_GEN_PROGS_aarch64 += aarch64/vgic_irq
diff --git a/tools/testing/selftests/kvm/aarch64/smccc_filter.c b/tools/testing/selftests/kvm/aarch64/smccc_filter.c
new file mode 100644
index 000000000000..f4ceae9c8925
--- /dev/null
+++ b/tools/testing/selftests/kvm/aarch64/smccc_filter.c
@@ -0,0 +1,268 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * smccc_filter - Tests for the SMCCC filter UAPI.
+ *
+ * Copyright (c) 2023 Google LLC
+ *
+ * This test includes:
+ *  - Tests that the UAPI constraints are upheld by KVM. For example, userspace
+ *    is prevented from filtering the architecture range of SMCCC calls.
+ *  - Test that the filter actions (DENIED, FWD_TO_USER) work as intended.
+ */
+
+#include <linux/arm-smccc.h>
+#include <linux/psci.h>
+#include <stdint.h>
+
+#include "processor.h"
+#include "test_util.h"
+
+enum smccc_conduit {
+	HVC_INSN,
+	SMC_INSN,
+};
+
+#define for_each_conduit(conduit)					\
+	for (conduit = HVC_INSN; conduit <= SMC_INSN; conduit++)
+
+static void guest_main(uint32_t func_id, enum smccc_conduit conduit)
+{
+	struct arm_smccc_res res;
+
+	if (conduit == SMC_INSN)
+		smccc_smc(func_id, 0, 0, 0, 0, 0, 0, 0, &res);
+	else
+		smccc_hvc(func_id, 0, 0, 0, 0, 0, 0, 0, &res);
+
+	GUEST_SYNC(res.a0);
+}
+
+static int __set_smccc_filter(struct kvm_vm *vm, uint32_t start, uint32_t nr_functions,
+			      enum kvm_smccc_filter_action action)
+{
+	struct kvm_smccc_filter filter = {
+		.base		= start,
+		.nr_functions	= nr_functions,
+		.action		= action,
+	};
+
+	return __kvm_device_attr_set(vm->fd, KVM_ARM_VM_SMCCC_CTRL,
+				     KVM_ARM_VM_SMCCC_FILTER, &filter);
+}
+
+static void set_smccc_filter(struct kvm_vm *vm, uint32_t start, uint32_t nr_functions,
+			     enum kvm_smccc_filter_action action)
+{
+	int ret = __set_smccc_filter(vm, start, nr_functions, action);
+
+	TEST_ASSERT(!ret, "failed to configure SMCCC filter: %d", ret);
+}
+
+static struct kvm_vm *setup_vm(struct kvm_vcpu **vcpu)
+{
+	struct kvm_vcpu_init init;
+	struct kvm_vm *vm;
+
+	vm = vm_create(1);
+	vm_ioctl(vm, KVM_ARM_PREFERRED_TARGET, &init);
+
+	/*
+	 * Enable in-kernel emulation of PSCI to ensure that calls are denied
+	 * due to the SMCCC filter, not because of KVM.
+	 */
+	init.features[0] |= (1 << KVM_ARM_VCPU_PSCI_0_2);
+
+	*vcpu = aarch64_vcpu_add(vm, 0, &init, guest_main);
+	return vm;
+}
+
+static void test_pad_must_be_zero(void)
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm = setup_vm(&vcpu);
+	struct kvm_smccc_filter filter = {
+		.base		= PSCI_0_2_FN_PSCI_VERSION,
+		.nr_functions	= 1,
+		.action		= KVM_SMCCC_FILTER_DENY,
+		.pad		= { -1 },
+	};
+	int r;
+
+	r = __kvm_device_attr_set(vm->fd, KVM_ARM_VM_SMCCC_CTRL,
+				  KVM_ARM_VM_SMCCC_FILTER, &filter);
+	TEST_ASSERT(r < 0 && errno == EINVAL,
+		    "Setting filter with nonzero padding should return EINVAL");
+}
+
+/* Ensure that userspace cannot filter the Arm Architecture SMCCC range */
+static void test_filter_reserved_range(void)
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm = setup_vm(&vcpu);
+	uint32_t smc64_fn;
+	int r;
+
+	r = __set_smccc_filter(vm, ARM_SMCCC_ARCH_WORKAROUND_1,
+			       1, KVM_SMCCC_FILTER_DENY);
+	TEST_ASSERT(r < 0 && errno == EEXIST,
+		    "Attempt to filter reserved range should return EEXIST");
+
+	smc64_fn = ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, ARM_SMCCC_SMC_64,
+				      0, 0);
+
+	r = __set_smccc_filter(vm, smc64_fn, 1, KVM_SMCCC_FILTER_DENY);
+	TEST_ASSERT(r < 0 && errno == EEXIST,
+		    "Attempt to filter reserved range should return EEXIST");
+
+	kvm_vm_free(vm);
+}
+
+static void test_invalid_nr_functions(void)
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm = setup_vm(&vcpu);
+	int r;
+
+	r = __set_smccc_filter(vm, PSCI_0_2_FN64_CPU_ON, 0, KVM_SMCCC_FILTER_DENY);
+	TEST_ASSERT(r < 0 && errno == EINVAL,
+		    "Attempt to filter 0 functions should return EINVAL");
+
+	kvm_vm_free(vm);
+}
+
+static void test_overflow_nr_functions(void)
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm = setup_vm(&vcpu);
+	int r;
+
+	r = __set_smccc_filter(vm, ~0, ~0, KVM_SMCCC_FILTER_DENY);
+	TEST_ASSERT(r < 0 && errno == EINVAL,
+		    "Attempt to overflow filter range should return EINVAL");
+
+	kvm_vm_free(vm);
+}
+
+static void test_reserved_action(void)
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm = setup_vm(&vcpu);
+	int r;
+
+	r = __set_smccc_filter(vm, PSCI_0_2_FN64_CPU_ON, 1, -1);
+	TEST_ASSERT(r < 0 && errno == EINVAL,
+		    "Attempt to use reserved filter action should return EINVAL");
+
+	kvm_vm_free(vm);
+}
+
+
+/* Test that overlapping configurations of the SMCCC filter are rejected */
+static void test_filter_overlap(void)
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm = setup_vm(&vcpu);
+	int r;
+
+	set_smccc_filter(vm, PSCI_0_2_FN64_CPU_ON, 1, KVM_SMCCC_FILTER_DENY);
+
+	r = __set_smccc_filter(vm, PSCI_0_2_FN64_CPU_ON, 1, KVM_SMCCC_FILTER_DENY);
+	TEST_ASSERT(r < 0 && errno == EEXIST,
+		    "Attempt to filter already configured range should return EEXIST");
+
+	kvm_vm_free(vm);
+}
+
+static void expect_call_denied(struct kvm_vcpu *vcpu)
+{
+	struct ucall uc;
+
+	if (get_ucall(vcpu, &uc) != UCALL_SYNC)
+		TEST_FAIL("Unexpected ucall: %lu\n", uc.cmd);
+
+	TEST_ASSERT(uc.args[1] == SMCCC_RET_NOT_SUPPORTED,
+		    "Unexpected SMCCC return code: %lu", uc.args[1]);
+}
+
+/* Denied SMCCC calls have a return code of SMCCC_RET_NOT_SUPPORTED */
+static void test_filter_denied(void)
+{
+	enum smccc_conduit conduit;
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm;
+
+	for_each_conduit(conduit) {
+		vm = setup_vm(&vcpu);
+
+		set_smccc_filter(vm, PSCI_0_2_FN_PSCI_VERSION, 1, KVM_SMCCC_FILTER_DENY);
+		vcpu_args_set(vcpu, 2, PSCI_0_2_FN_PSCI_VERSION, conduit);
+
+		vcpu_run(vcpu);
+		expect_call_denied(vcpu);
+
+		kvm_vm_free(vm);
+	}
+}
+
+static void expect_call_fwd_to_user(struct kvm_vcpu *vcpu, uint32_t func_id,
+				    enum smccc_conduit conduit)
+{
+	struct kvm_run *run = vcpu->run;
+
+	TEST_ASSERT(run->exit_reason == KVM_EXIT_HYPERCALL,
+		    "Unexpected exit reason: %u", run->exit_reason);
+	TEST_ASSERT(run->hypercall.nr == func_id,
+		    "Unexpected SMCCC function: %llu", run->hypercall.nr);
+
+	if (conduit == SMC_INSN)
+		TEST_ASSERT(run->hypercall.flags & KVM_HYPERCALL_EXIT_SMC,
+			    "KVM_HYPERCALL_EXIT_SMC is not set");
+	else
+		TEST_ASSERT(!(run->hypercall.flags & KVM_HYPERCALL_EXIT_SMC),
+			    "KVM_HYPERCALL_EXIT_SMC is set");
+}
+
+/* SMCCC calls forwarded to userspace cause KVM_EXIT_HYPERCALL exits */
+static void test_filter_fwd_to_user(void)
+{
+	enum smccc_conduit conduit;
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm;
+
+	for_each_conduit(conduit) {
+		vm = setup_vm(&vcpu);
+
+		set_smccc_filter(vm, PSCI_0_2_FN_PSCI_VERSION, 1, KVM_SMCCC_FILTER_FWD_TO_USER);
+		vcpu_args_set(vcpu, 2, PSCI_0_2_FN_PSCI_VERSION, conduit);
+
+		vcpu_run(vcpu);
+		expect_call_fwd_to_user(vcpu, PSCI_0_2_FN_PSCI_VERSION, conduit);
+
+		kvm_vm_free(vm);
+	}
+}
+
+static bool kvm_supports_smccc_filter(void)
+{
+	struct kvm_vm *vm = vm_create_barebones();
+	int r;
+
+	r = __kvm_has_device_attr(vm->fd, KVM_ARM_VM_SMCCC_CTRL, KVM_ARM_VM_SMCCC_FILTER);
+
+	kvm_vm_free(vm);
+	return !r;
+}
+
+int main(void)
+{
+	TEST_REQUIRE(kvm_supports_smccc_filter());
+
+	test_pad_must_be_zero();
+	test_invalid_nr_functions();
+	test_overflow_nr_functions();
+	test_reserved_action();
+	test_filter_reserved_range();
+	test_filter_overlap();
+	test_filter_denied();
+	test_filter_fwd_to_user();
+}
diff --git a/tools/testing/selftests/kvm/include/aarch64/processor.h b/tools/testing/selftests/kvm/include/aarch64/processor.h
index 5f977528e09c..cb537253a6b9 100644
--- a/tools/testing/selftests/kvm/include/aarch64/processor.h
+++ b/tools/testing/selftests/kvm/include/aarch64/processor.h
@@ -214,6 +214,19 @@ void smccc_hvc(uint32_t function_id, uint64_t arg0, uint64_t arg1,
 	       uint64_t arg2, uint64_t arg3, uint64_t arg4, uint64_t arg5,
 	       uint64_t arg6, struct arm_smccc_res *res);
 
+/**
+ * smccc_smc - Invoke a SMCCC function using the smc conduit
+ * @function_id: the SMCCC function to be called
+ * @arg0-arg6: SMCCC function arguments, corresponding to registers x1-x7
+ * @res: pointer to write the return values from registers x0-x3
+ *
+ */
+void smccc_smc(uint32_t function_id, uint64_t arg0, uint64_t arg1,
+	       uint64_t arg2, uint64_t arg3, uint64_t arg4, uint64_t arg5,
+	       uint64_t arg6, struct arm_smccc_res *res);
+
+
+
 uint32_t guest_get_vcpuid(void);
 
 #endif /* SELFTEST_KVM_PROCESSOR_H */
diff --git a/tools/testing/selftests/kvm/lib/aarch64/processor.c b/tools/testing/selftests/kvm/lib/aarch64/processor.c
index 233357d2f1cc..3a0259e25335 100644
--- a/tools/testing/selftests/kvm/lib/aarch64/processor.c
+++ b/tools/testing/selftests/kvm/lib/aarch64/processor.c
@@ -527,29 +527,43 @@ void aarch64_get_supported_page_sizes(uint32_t ipa,
 	close(kvm_fd);
 }
 
+#define __smccc_call(insn, function_id, arg0, arg1, arg2, arg3, arg4, arg5,	\
+		     arg6, res)							\
+	asm volatile("mov   w0, %w[function_id]\n"				\
+		     "mov   x1, %[arg0]\n"					\
+		     "mov   x2, %[arg1]\n"					\
+		     "mov   x3, %[arg2]\n"					\
+		     "mov   x4, %[arg3]\n"					\
+		     "mov   x5, %[arg4]\n"					\
+		     "mov   x6, %[arg5]\n"					\
+		     "mov   x7, %[arg6]\n"					\
+		     #insn  "#0\n"						\
+		     "mov   %[res0], x0\n"					\
+		     "mov   %[res1], x1\n"					\
+		     "mov   %[res2], x2\n"					\
+		     "mov   %[res3], x3\n"					\
+		     : [res0] "=r"(res->a0), [res1] "=r"(res->a1),		\
+		       [res2] "=r"(res->a2), [res3] "=r"(res->a3)		\
+		     : [function_id] "r"(function_id), [arg0] "r"(arg0),	\
+		       [arg1] "r"(arg1), [arg2] "r"(arg2), [arg3] "r"(arg3),	\
+		       [arg4] "r"(arg4), [arg5] "r"(arg5), [arg6] "r"(arg6)	\
+		     : "x0", "x1", "x2", "x3", "x4", "x5", "x6", "x7")
+
+
 void smccc_hvc(uint32_t function_id, uint64_t arg0, uint64_t arg1,
 	       uint64_t arg2, uint64_t arg3, uint64_t arg4, uint64_t arg5,
 	       uint64_t arg6, struct arm_smccc_res *res)
 {
-	asm volatile("mov   w0, %w[function_id]\n"
-		     "mov   x1, %[arg0]\n"
-		     "mov   x2, %[arg1]\n"
-		     "mov   x3, %[arg2]\n"
-		     "mov   x4, %[arg3]\n"
-		     "mov   x5, %[arg4]\n"
-		     "mov   x6, %[arg5]\n"
-		     "mov   x7, %[arg6]\n"
-		     "hvc   #0\n"
-		     "mov   %[res0], x0\n"
-		     "mov   %[res1], x1\n"
-		     "mov   %[res2], x2\n"
-		     "mov   %[res3], x3\n"
-		     : [res0] "=r"(res->a0), [res1] "=r"(res->a1),
-		       [res2] "=r"(res->a2), [res3] "=r"(res->a3)
-		     : [function_id] "r"(function_id), [arg0] "r"(arg0),
-		       [arg1] "r"(arg1), [arg2] "r"(arg2), [arg3] "r"(arg3),
-		       [arg4] "r"(arg4), [arg5] "r"(arg5), [arg6] "r"(arg6)
-		     : "x0", "x1", "x2", "x3", "x4", "x5", "x6", "x7");
+	__smccc_call(hvc, function_id, arg0, arg1, arg2, arg3, arg4, arg5,
+		     arg6, res);
+}
+
+void smccc_smc(uint32_t function_id, uint64_t arg0, uint64_t arg1,
+	       uint64_t arg2, uint64_t arg3, uint64_t arg4, uint64_t arg5,
+	       uint64_t arg6, struct arm_smccc_res *res)
+{
+	__smccc_call(smc, function_id, arg0, arg1, arg2, arg3, arg4, arg5,
+		     arg6, res);
 }
 
 void kvm_selftest_arch_init(void)