[kvm-unit-tests PATCH v5 0/4] Add additional testing for routing L2 exceptions

[kvm-unit-tests PATCH v5 0/4] Add additional testing for routing L2 exceptions

[Aaron Lewis]

In a previous series testing was added to verify that when a #PF occured
in L2 the exception was routed to the correct place.  In this series
other exceptions are tested (ie: #GP, #UD, #DE, #DB, #BP, #AC).

v4 -> v5:
 - Removed vmx_exception_test from being able to be run on its own.
   It can only be run as a part of vmx now.
 - Removed vmx_exception_test from vmx in unittests.cfg.  Having
   it in that list filters the test from running.  With it removed
   it now runs as a part of vmx.
 - Split the commit for test_override_guest()
   and test_set_guest_finished() into two commits.
 - Fixed up vmx_l2_ac_test() and usermode_callback() based on feedback.

v3 -> v4:
 - Add vmx_exception_test to vmx.

v2 -> v3:
 - Commits 1 and 2 from v2 were accepted upstream (bug fixes).
 - Moved exception_mnemonic() into a separate commit.
 - Moved support for running a nested guest multiple times in
   one test into a separate commit.
 - Moved the test framework into the same commit as the test itself.
 - Simplified the test framework and test code based on Sean's
   recommendations.

v1 -> v2:
 - Add guest_stack_top and guest_syscall_stack_top for aligning L2's
   stacks.
 - Refactor test to make it more extensible (ie: Added
   vmx_exception_tests array and framework around it).
 - Split test into 2 commits:
   1. Test infrustructure.
   2. Test cases.

Aaron Lewis (4):
  x86: Make exception_mnemonic() visible to the tests
  x86: Add support for running a nested guest multiple times in one test
  x86: Add a helper to allow tests to signal completion without a
    vmcall()
  x86: Add test coverage for nested_vmx_reflect_vmexit() testing

 lib/x86/desc.c  |   2 +-
 lib/x86/desc.h  |   1 +
 x86/vmx.c       |  24 ++++++++-
 x86/vmx.h       |   2 +
 x86/vmx_tests.c | 130 ++++++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 156 insertions(+), 3 deletions(-)

-- 
2.35.0.rc0.227.g00780c9af4-goog

[kvm-unit-tests PATCH v5 1/4] x86: Make exception_mnemonic() visible to the tests

[Aaron Lewis]

exception_mnemonic() is a useful function for more than just desc.c.
Make it global, so it can be used in other KUT tests.

Signed-off-by: Aaron Lewis <aaronlewis@google.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
---
 lib/x86/desc.c | 2 +-
 lib/x86/desc.h | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/x86/desc.c b/lib/x86/desc.c
index 16b7256..c2eb16e 100644
--- a/lib/x86/desc.c
+++ b/lib/x86/desc.c
@@ -91,7 +91,7 @@ struct ex_record {
 
 extern struct ex_record exception_table_start, exception_table_end;
 
-static const char* exception_mnemonic(int vector)
+const char* exception_mnemonic(int vector)
 {
 	switch(vector) {
 	case 0: return "#DE";
diff --git a/lib/x86/desc.h b/lib/x86/desc.h
index 9b81da0..ad6277b 100644
--- a/lib/x86/desc.h
+++ b/lib/x86/desc.h
@@ -224,6 +224,7 @@ void set_intr_alt_stack(int e, void *fn);
 void print_current_tss_info(void);
 handler handle_exception(u8 v, handler fn);
 void unhandled_exception(struct ex_regs *regs, bool cpu);
+const char* exception_mnemonic(int vector);
 
 bool test_for_exception(unsigned int ex, void (*trigger_func)(void *data),
 			void *data);
-- 
2.35.0.rc0.227.g00780c9af4-goog

[kvm-unit-tests PATCH v5 2/4] x86: Add support for running a nested guest multiple times in one test

[Aaron Lewis]

KUT has a limit of only being able to run one nested guest per vmx test.
This is limiting and not necessary.  Add support for allowing a test to
run guest code multiple times.

Signed-off-by: Aaron Lewis <aaronlewis@google.com>
---
 x86/vmx.c | 19 +++++++++++++++++--
 x86/vmx.h |  1 +
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/x86/vmx.c b/x86/vmx.c
index f4fbb94..b2d8393 100644
--- a/x86/vmx.c
+++ b/x86/vmx.c
@@ -1884,15 +1884,30 @@ void test_add_teardown(test_teardown_func func, void *data)
 	step->data = data;
 }
 
+static void __test_set_guest(test_guest_func func)
+{
+	assert(current->v2);
+	v2_guest_main = func;
+}
+
 /*
  * Set the target of the first enter_guest call. Can only be called once per
  * test. Must be called before first enter_guest call.
  */
 void test_set_guest(test_guest_func func)
 {
-	assert(current->v2);
 	TEST_ASSERT_MSG(!v2_guest_main, "Already set guest func.");
-	v2_guest_main = func;
+	__test_set_guest(func);
+}
+
+/*
+ * Set the target of the enter_guest call and reset the RIP so 'func' will
+ * start from the beginning.  This can be called multiple times per test.
+ */
+void test_override_guest(test_guest_func func)
+{
+	__test_set_guest(func);
+	init_vmcs_guest();
 }
 
 static void check_for_guest_termination(union exit_reason exit_reason)
diff --git a/x86/vmx.h b/x86/vmx.h
index 4423986..dabd5da 100644
--- a/x86/vmx.h
+++ b/x86/vmx.h
@@ -1055,6 +1055,7 @@ void hypercall(u32 hypercall_no);
 typedef void (*test_guest_func)(void);
 typedef void (*test_teardown_func)(void *data);
 void test_set_guest(test_guest_func func);
+void test_override_guest(test_guest_func func);
 void test_add_teardown(test_teardown_func func, void *data);
 void test_skip(const char *msg);
 
-- 
2.35.0.rc0.227.g00780c9af4-goog

[kvm-unit-tests PATCH v5 3/4] x86: Add a helper to allow tests to signal completion without a vmcall()

[Aaron Lewis]

Putting a vmcall() at the end of a nested test isn't always convenient
to do, and isn't necessary.  Add a helper to allow the nested test
to make it possible to skip this requirement.

Signed-off-by: Aaron Lewis <aaronlewis@google.com>
---
 x86/vmx.c | 5 +++++
 x86/vmx.h | 1 +
 2 files changed, 6 insertions(+)

diff --git a/x86/vmx.c b/x86/vmx.c
index b2d8393..51eed8c 100644
--- a/x86/vmx.c
+++ b/x86/vmx.c
@@ -1910,6 +1910,11 @@ void test_override_guest(test_guest_func func)
 	init_vmcs_guest();
 }
 
+void test_set_guest_finished(void)
+{
+	guest_finished = 1;
+}
+
 static void check_for_guest_termination(union exit_reason exit_reason)
 {
 	if (is_hypercall(exit_reason)) {
diff --git a/x86/vmx.h b/x86/vmx.h
index dabd5da..11cb665 100644
--- a/x86/vmx.h
+++ b/x86/vmx.h
@@ -1058,5 +1058,6 @@ void test_set_guest(test_guest_func func);
 void test_override_guest(test_guest_func func);
 void test_add_teardown(test_teardown_func func, void *data);
 void test_skip(const char *msg);
+void test_set_guest_finished(void);
 
 #endif
-- 
2.35.0.rc0.227.g00780c9af4-goog

[kvm-unit-tests PATCH v5 4/4] x86: Add test coverage for nested_vmx_reflect_vmexit() testing

[Aaron Lewis]

Add a framework and test cases to ensure exceptions that occur in L2 are
forwarded to the correct place by nested_vmx_reflect_vmexit().

Add testing for exceptions: #GP, #UD, #DE, #DB, #BP, and #AC.

Signed-off-by: Aaron Lewis <aaronlewis@google.com>
---
 x86/vmx_tests.c | 130 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 130 insertions(+)

diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c
index 3d57ed6..796fd7b 100644
--- a/x86/vmx_tests.c
+++ b/x86/vmx_tests.c
@@ -21,6 +21,7 @@
 #include "smp.h"
 #include "delay.h"
 #include "access.h"
+#include "x86/usermode.h"
 
 #define VPID_CAP_INVVPID_TYPES_SHIFT 40
 
@@ -10701,6 +10702,134 @@ static void vmx_pf_vpid_test(void)
 	__vmx_pf_vpid_test(invalidate_tlb_new_vpid, 1);
 }
 
+static void vmx_l2_gp_test(void)
+{
+	*(volatile u64 *)NONCANONICAL = 0;
+}
+
+static void vmx_l2_ud_test(void)
+{
+	asm volatile ("ud2");
+}
+
+static void vmx_l2_de_test(void)
+{
+	asm volatile (
+		"xor %%eax, %%eax\n\t"
+		"xor %%ebx, %%ebx\n\t"
+		"xor %%edx, %%edx\n\t"
+		"idiv %%ebx\n\t"
+		::: "eax", "ebx", "edx");
+}
+
+static void vmx_l2_bp_test(void)
+{
+	asm volatile ("int3");
+}
+
+static void vmx_l2_db_test(void)
+{
+	write_rflags(read_rflags() | X86_EFLAGS_TF);
+}
+
+static uint64_t usermode_callback(void)
+{
+	/*
+	 * Trigger an #AC by writing 8 bytes to a 4-byte aligned address.
+	 * Disclaimer: It is assumed that the stack pointer is aligned
+	 * on a 16-byte boundary as x86_64 stacks should be.
+	 */
+	asm volatile("movq $0, -0x4(%rsp)");
+
+	return 0;
+}
+
+static void vmx_l2_ac_test(void)
+{
+	bool hit_ac = false;
+
+	write_cr0(read_cr0() | X86_CR0_AM);
+	write_rflags(read_rflags() | X86_EFLAGS_AC);
+
+	run_in_user(usermode_callback, AC_VECTOR, 0, 0, 0, 0, &hit_ac);
+	report(hit_ac, "Usermode #AC handled in L2");
+	vmcall();
+}
+
+struct vmx_exception_test {
+	u8 vector;
+	void (*guest_code)(void);
+};
+
+struct vmx_exception_test vmx_exception_tests[] = {
+	{ GP_VECTOR, vmx_l2_gp_test },
+	{ UD_VECTOR, vmx_l2_ud_test },
+	{ DE_VECTOR, vmx_l2_de_test },
+	{ DB_VECTOR, vmx_l2_db_test },
+	{ BP_VECTOR, vmx_l2_bp_test },
+	{ AC_VECTOR, vmx_l2_ac_test },
+};
+
+static u8 vmx_exception_test_vector;
+
+static void vmx_exception_handler(struct ex_regs *regs)
+{
+	report(regs->vector == vmx_exception_test_vector,
+	       "Handling %s in L2's exception handler",
+	       exception_mnemonic(vmx_exception_test_vector));
+	vmcall();
+}
+
+static void handle_exception_in_l2(u8 vector)
+{
+	handler old_handler = handle_exception(vector, vmx_exception_handler);
+
+	vmx_exception_test_vector = vector;
+
+	enter_guest();
+	report(vmcs_read(EXI_REASON) == VMX_VMCALL,
+	       "%s handled by L2", exception_mnemonic(vector));
+
+	handle_exception(vector, old_handler);
+}
+
+static void handle_exception_in_l1(u32 vector)
+{
+	u32 old_eb = vmcs_read(EXC_BITMAP);
+
+	vmcs_write(EXC_BITMAP, old_eb | (1u << vector));
+
+	enter_guest();
+
+	report((vmcs_read(EXI_REASON) == VMX_EXC_NMI) &&
+	       ((vmcs_read(EXI_INTR_INFO) & 0xff) == vector),
+	       "%s handled by L1", exception_mnemonic(vector));
+
+	vmcs_write(EXC_BITMAP, old_eb);
+}
+
+static void vmx_exception_test(void)
+{
+	struct vmx_exception_test *t;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(vmx_exception_tests); i++) {
+		t = &vmx_exception_tests[i];
+
+		/*
+		 * Override the guest code before each run even though it's the
+		 * same code, the VMCS guest state needs to be reinitialized.
+		 */
+		test_override_guest(t->guest_code);
+		handle_exception_in_l2(t->vector);
+
+		test_override_guest(t->guest_code);
+		handle_exception_in_l1(t->vector);
+	}
+
+	test_set_guest_finished();
+}
+
 #define TEST(name) { #name, .v2 = name }
 
 /* name/init/guest_main/exit_handler/syscall_handler/guest_regs */
@@ -10810,5 +10939,6 @@ struct vmx_test vmx_tests[] = {
 	TEST(vmx_pf_no_vpid_test),
 	TEST(vmx_pf_invvpid_test),
 	TEST(vmx_pf_vpid_test),
+	TEST(vmx_exception_test),
 	{ NULL, NULL, NULL, NULL, NULL, {0} },
 };
-- 
2.35.0.rc0.227.g00780c9af4-goog