Merge branch 'kvm-svm-harden' into HEAD

This fixes three issues in nested SVM:

1) in the shutdown_interception() vmexit handler we call kvm_vcpu_reset().
However, if running nested and L1 doesn't intercept shutdown, the function
resets vcpu->arch.hflags without properly leaving the nested state.
This leaves the vCPU in inconsistent state and later triggers a kernel
panic in SVM code.  The same bug can likely be triggered by sending INIT
via local apic to a vCPU which runs a nested guest.

On VMX we are lucky that the issue can't happen because VMX always
intercepts triple faults, thus triple fault in L2 will always be
redirected to L1.  Plus, handle_triple_fault() doesn't reset the vCPU.
INIT IPI can't happen on VMX either because INIT events are masked while
in VMX mode.

Secondarily, KVM doesn't honour SHUTDOWN intercept bit of L1 on SVM.
A normal hypervisor should always intercept SHUTDOWN, a unit test on
the other hand might want to not do so.

Finally, the guest can trigger a kernel non rate limited printk on SVM
from the guest, which is fixed as well.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

6 files changed, 138 insertions, 30 deletions

diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
index bef984e4c39d..582e2e198fbf 100644
--- a/tools/testing/selftests/kvm/.gitignore
+++ b/tools/testing/selftests/kvm/.gitignore
@@ -42,6 +42,7 @@
 /x86_64/svm_vmcall_test
 /x86_64/svm_int_ctl_test
 /x86_64/svm_nested_soft_inject_test
+/x86_64/svm_nested_shutdown_test
 /x86_64/sync_regs_test
 /x86_64/tsc_msrs_test
 /x86_64/tsc_scaling_sync
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index 487248c67dec..f62dcfcda618 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -103,6 +103,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/state_test
 TEST_GEN_PROGS_x86_64 += x86_64/vmx_preemption_timer_test
 TEST_GEN_PROGS_x86_64 += x86_64/svm_vmcall_test
 TEST_GEN_PROGS_x86_64 += x86_64/svm_int_ctl_test
+TEST_GEN_PROGS_x86_64 += x86_64/svm_nested_shutdown_test
 TEST_GEN_PROGS_x86_64 += x86_64/svm_nested_soft_inject_test
 TEST_GEN_PROGS_x86_64 += x86_64/tsc_scaling_sync
 TEST_GEN_PROGS_x86_64 += x86_64/sync_regs_test
diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
index 481f44c683aa..f838ac5865dc 100644
--- a/tools/testing/selftests/kvm/include/x86_64/processor.h
+++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
@@ -929,6 +929,19 @@ struct ex_regs {
 	uint64_t rflags;
 };
 
+struct idt_entry {
+	uint16_t offset0;
+	uint16_t selector;
+	uint16_t ist : 3;
+	uint16_t : 5;
+	uint16_t type : 4;
+	uint16_t : 1;
+	uint16_t dpl : 2;
+	uint16_t p : 1;
+	uint16_t offset1;
+	uint32_t offset2; uint32_t reserved;
+};
+
 void vm_init_descriptor_tables(struct kvm_vm *vm);
 void vcpu_init_descriptor_tables(struct kvm_vcpu *vcpu);
 void vm_install_exception_handler(struct kvm_vm *vm, int vector,
diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
index 65e87b5acb6f..d532c20c74fd 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
@@ -1034,19 +1034,6 @@ void kvm_get_cpu_address_width(unsigned int *pa_bits, unsigned int *va_bits)
 	}
 }
 
-struct idt_entry {
-	uint16_t offset0;
-	uint16_t selector;
-	uint16_t ist : 3;
-	uint16_t : 5;
-	uint16_t type : 4;
-	uint16_t : 1;
-	uint16_t dpl : 2;
-	uint16_t p : 1;
-	uint16_t offset1;
-	uint32_t offset2; uint32_t reserved;
-};
-
 static void set_idt_entry(struct kvm_vm *vm, int vector, unsigned long addr,
 			  int dpl, unsigned short selector)
 {
diff --git a/tools/testing/selftests/kvm/x86_64/svm_nested_shutdown_test.c b/tools/testing/selftests/kvm/x86_64/svm_nested_shutdown_test.c
new file mode 100644
index 000000000000..e73fcdef47bb
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86_64/svm_nested_shutdown_test.c
@@ -0,0 +1,67 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * svm_nested_shutdown_test
+ *
+ * Copyright (C) 2022, Red Hat, Inc.
+ *
+ * Nested SVM testing: test that unintercepted shutdown in L2 doesn't crash the host
+ */
+
+#include "test_util.h"
+#include "kvm_util.h"
+#include "processor.h"
+#include "svm_util.h"
+
+static void l2_guest_code(struct svm_test_data *svm)
+{
+	__asm__ __volatile__("ud2");
+}
+
+static void l1_guest_code(struct svm_test_data *svm, struct idt_entry *idt)
+{
+	#define L2_GUEST_STACK_SIZE 64
+	unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
+	struct vmcb *vmcb = svm->vmcb;
+
+	generic_svm_setup(svm, l2_guest_code,
+			  &l2_guest_stack[L2_GUEST_STACK_SIZE]);
+
+	vmcb->control.intercept &= ~(BIT(INTERCEPT_SHUTDOWN));
+
+	idt[6].p   = 0; // #UD is intercepted but its injection will cause #NP
+	idt[11].p  = 0; // #NP is not intercepted and will cause another
+			// #NP that will be converted to #DF
+	idt[8].p   = 0; // #DF will cause #NP which will cause SHUTDOWN
+
+	run_guest(vmcb, svm->vmcb_gpa);
+
+	/* should not reach here */
+	GUEST_ASSERT(0);
+}
+
+int main(int argc, char *argv[])
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_run *run;
+	vm_vaddr_t svm_gva;
+	struct kvm_vm *vm;
+
+	TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_SVM));
+
+	vm = vm_create_with_one_vcpu(&vcpu, l1_guest_code);
+	vm_init_descriptor_tables(vm);
+	vcpu_init_descriptor_tables(vcpu);
+
+	vcpu_alloc_svm(vm, &svm_gva);
+
+	vcpu_args_set(vcpu, 2, svm_gva, vm->idt);
+	run = vcpu->run;
+
+	vcpu_run(vcpu);
+	TEST_ASSERT(run->exit_reason == KVM_EXIT_SHUTDOWN,
+		    "Got exit_reason other than KVM_EXIT_SHUTDOWN: %u (%s)\n",
+		    run->exit_reason,
+		    exit_reason_str(run->exit_reason));
+
+	kvm_vm_free(vm);
+}
diff --git a/tools/testing/selftests/kvm/x86_64/triple_fault_event_test.c b/tools/testing/selftests/kvm/x86_64/triple_fault_event_test.c
index 70b44f0b52fe..ead5d878a71c 100644
--- a/tools/testing/selftests/kvm/x86_64/triple_fault_event_test.c
+++ b/tools/testing/selftests/kvm/x86_64/triple_fault_event_test.c
@@ -3,6 +3,7 @@
 #include "kvm_util.h"
 #include "processor.h"
 #include "vmx.h"
+#include "svm_util.h"
 
 #include <string.h>
 #include <sys/ioctl.h>
@@ -20,10 +21,11 @@ static void l2_guest_code(void)
 		     : : [port] "d" (ARBITRARY_IO_PORT) : "rax");
 }
 
-void l1_guest_code(struct vmx_pages *vmx)
-{
 #define L2_GUEST_STACK_SIZE 64
-	unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
+unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
+
+void l1_guest_code_vmx(struct vmx_pages *vmx)
+{
 
 	GUEST_ASSERT(vmx->vmcs_gpa);
 	GUEST_ASSERT(prepare_for_vmx_operation(vmx));
@@ -38,24 +40,53 @@ void l1_guest_code(struct vmx_pages *vmx)
 	GUEST_DONE();
 }
 
+void l1_guest_code_svm(struct svm_test_data *svm)
+{
+	struct vmcb *vmcb = svm->vmcb;
+
+	generic_svm_setup(svm, l2_guest_code,
+			&l2_guest_stack[L2_GUEST_STACK_SIZE]);
+
+	/* don't intercept shutdown to test the case of SVM allowing to do so */
+	vmcb->control.intercept &= ~(BIT(INTERCEPT_SHUTDOWN));
+
+	run_guest(vmcb, svm->vmcb_gpa);
+
+	/* should not reach here, L1 should crash  */
+	GUEST_ASSERT(0);
+}
+
 int main(void)
 {
 	struct kvm_vcpu *vcpu;
 	struct kvm_run *run;
 	struct kvm_vcpu_events events;
-	vm_vaddr_t vmx_pages_gva;
 	struct ucall uc;
 
-	TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_VMX));
+	bool has_vmx = kvm_cpu_has(X86_FEATURE_VMX);
+	bool has_svm = kvm_cpu_has(X86_FEATURE_SVM);
+
+	TEST_REQUIRE(has_vmx || has_svm);
 
 	TEST_REQUIRE(kvm_has_cap(KVM_CAP_X86_TRIPLE_FAULT_EVENT));
 
-	vm = vm_create_with_one_vcpu(&vcpu, l1_guest_code);
-	vm_enable_cap(vm, KVM_CAP_X86_TRIPLE_FAULT_EVENT, 1);
 
+	if (has_vmx) {
+		vm_vaddr_t vmx_pages_gva;
+
+		vm = vm_create_with_one_vcpu(&vcpu, l1_guest_code_vmx);
+		vcpu_alloc_vmx(vm, &vmx_pages_gva);
+		vcpu_args_set(vcpu, 1, vmx_pages_gva);
+	} else {
+		vm_vaddr_t svm_gva;
+
+		vm = vm_create_with_one_vcpu(&vcpu, l1_guest_code_svm);
+		vcpu_alloc_svm(vm, &svm_gva);
+		vcpu_args_set(vcpu, 1, svm_gva);
+	}
+
+	vm_enable_cap(vm, KVM_CAP_X86_TRIPLE_FAULT_EVENT, 1);
 	run = vcpu->run;
-	vcpu_alloc_vmx(vm, &vmx_pages_gva);
-	vcpu_args_set(vcpu, 1, vmx_pages_gva);
 	vcpu_run(vcpu);
 
 	TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
@@ -78,13 +109,21 @@ int main(void)
 		    "No triple fault pending");
 	vcpu_run(vcpu);
 
-	switch (get_ucall(vcpu, &uc)) {
-	case UCALL_DONE:
-		break;
-	case UCALL_ABORT:
-		REPORT_GUEST_ASSERT(uc);
-	default:
-		TEST_FAIL("Unexpected ucall: %lu", uc.cmd);
-	}
 
+	if (has_svm) {
+		TEST_ASSERT(run->exit_reason == KVM_EXIT_SHUTDOWN,
+			    "Got exit_reason other than KVM_EXIT_SHUTDOWN: %u (%s)\n",
+			    run->exit_reason,
+			    exit_reason_str(run->exit_reason));
+	} else {
+		switch (get_ucall(vcpu, &uc)) {
+		case UCALL_DONE:
+			break;
+		case UCALL_ABORT:
+			REPORT_GUEST_ASSERT(uc);
+		default:
+			TEST_FAIL("Unexpected ucall: %lu", uc.cmd);
+		}
+	}
+	return 0;
 }