[kvm-unit-tests PATCH v3 01/20] x86/vmx: Drop unused SYSENTER "support" in nested VMX infrastructure

[Sean Christopherson <seanjc@google.com>]

Drop the unused SYSTENTER "support" from the nested VMX infrastructure, in
quotes because the code is half-baked (and that's being generous) and
likely has never been used.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 x86/vmx.c       | 32 +++++---------------------------
 x86/vmx.h       | 20 --------------------
 x86/vmx_tests.c | 45 +++++++++++++++++++++------------------------
 3 files changed, 26 insertions(+), 71 deletions(-)

diff --git a/x86/vmx.c b/x86/vmx.c
index eb2965d8..2b85ef0b 100644
--- a/x86/vmx.c
+++ b/x86/vmx.c
@@ -42,7 +42,7 @@
 u64 *bsp_vmxon_region;
 struct vmcs *vmcs_root;
 u32 vpid_cnt;
-u64 guest_stack_top, guest_syscall_stack_top;
+u64 guest_stack_top;
 u32 ctrl_pin, ctrl_enter, ctrl_exit, ctrl_cpu[2];
 struct regs regs;
 
@@ -76,7 +76,6 @@ union vmx_ept_vpid  ept_vpid;
 extern struct descriptor_table_ptr gdt_descr;
 extern struct descriptor_table_ptr idt_descr;
 extern void *vmx_return;
-extern void *entry_sysenter;
 extern void *guest_entry;
 
 static volatile u32 stage;
@@ -561,25 +560,6 @@ void vmx_inc_test_stage(void)
 	barrier();
 }
 
-/* entry_sysenter */
-asm(
-	".align	4, 0x90\n\t"
-	".globl	entry_sysenter\n\t"
-	"entry_sysenter:\n\t"
-	SAVE_GPR
-	"	and	$0xf, %rax\n\t"
-	"	mov	%rax, %rdi\n\t"
-	"	call	syscall_handler\n\t"
-	LOAD_GPR
-	"	vmresume\n\t"
-);
-
-static void __attribute__((__used__)) syscall_handler(u64 syscall_no)
-{
-	if (current->syscall_handler)
-		current->syscall_handler(syscall_no);
-}
-
 static const char * const exit_reason_descriptions[] = {
 	[VMX_EXC_NMI]		= "VMX_EXC_NMI",
 	[VMX_EXTINT]		= "VMX_EXTINT",
@@ -1123,7 +1103,7 @@ static void init_vmcs_host(void)
 	vmcs_write(HOST_CR0, read_cr0());
 	vmcs_write(HOST_CR3, read_cr3());
 	vmcs_write(HOST_CR4, read_cr4());
-	vmcs_write(HOST_SYSENTER_EIP, (u64)(&entry_sysenter));
+	vmcs_write(HOST_SYSENTER_EIP, rdmsr(MSR_IA32_SYSENTER_EIP));
 	vmcs_write(HOST_SYSENTER_CS,  KERNEL_CS);
 	if (ctrl_exit_rev.clr & EXI_LOAD_PAT)
 		vmcs_write(HOST_PAT, rdmsr(MSR_IA32_CR_PAT));
@@ -1172,8 +1152,8 @@ static void init_vmcs_guest(void)
 	vmcs_write(GUEST_CR3, guest_cr3);
 	vmcs_write(GUEST_CR4, guest_cr4);
 	vmcs_write(GUEST_SYSENTER_CS,  KERNEL_CS);
-	vmcs_write(GUEST_SYSENTER_ESP, guest_syscall_stack_top);
-	vmcs_write(GUEST_SYSENTER_EIP, (u64)(&entry_sysenter));
+	vmcs_write(GUEST_SYSENTER_ESP, rdmsr(MSR_IA32_SYSENTER_ESP));
+	vmcs_write(GUEST_SYSENTER_EIP, rdmsr(MSR_IA32_SYSENTER_EIP));
 	vmcs_write(GUEST_DR7, 0);
 	vmcs_write(GUEST_EFER, rdmsr(MSR_EFER));
 
@@ -1319,7 +1299,6 @@ static void alloc_bsp_vmx_pages(void)
 {
 	bsp_vmxon_region = alloc_page();
 	guest_stack_top = (uintptr_t)alloc_page() + PAGE_SIZE;
-	guest_syscall_stack_top = (uintptr_t)alloc_page() + PAGE_SIZE;
 	vmcs_root = alloc_page();
 }
 
@@ -1840,8 +1819,7 @@ static int test_run(struct vmx_test *test)
 	/* Validate V2 interface. */
 	if (test->v2) {
 		int ret = 0;
-		if (test->init || test->guest_main || test->exit_handler ||
-		    test->syscall_handler) {
+		if (test->init || test->guest_main || test->exit_handler) {
 			report_fail("V2 test cannot specify V1 callbacks.");
 			ret = 1;
 		}
diff --git a/x86/vmx.h b/x86/vmx.h
index 7ad7672a..f4ed5339 100644
--- a/x86/vmx.h
+++ b/x86/vmx.h
@@ -121,7 +121,6 @@ struct vmx_test {
 	int (*init)(struct vmcs *vmcs);
 	void (*guest_main)(void);
 	int (*exit_handler)(union exit_reason exit_reason);
-	void (*syscall_handler)(u64 syscall_no);
 	struct regs guest_regs;
 	int (*entry_failure_handler)(struct vmentry_result *result);
 	struct vmcs *vmcs;
@@ -589,25 +588,6 @@ enum vm_entry_failure_code {
 	ENTRY_FAIL_VMCS_LINK_PTR	= 4,
 };
 
-#define SAVE_GPR				\
-	"xchg %rax, regs\n\t"			\
-	"xchg %rcx, regs+0x8\n\t"		\
-	"xchg %rdx, regs+0x10\n\t"		\
-	"xchg %rbx, regs+0x18\n\t"		\
-	"xchg %rbp, regs+0x28\n\t"		\
-	"xchg %rsi, regs+0x30\n\t"		\
-	"xchg %rdi, regs+0x38\n\t"		\
-	"xchg %r8, regs+0x40\n\t"		\
-	"xchg %r9, regs+0x48\n\t"		\
-	"xchg %r10, regs+0x50\n\t"		\
-	"xchg %r11, regs+0x58\n\t"		\
-	"xchg %r12, regs+0x60\n\t"		\
-	"xchg %r13, regs+0x68\n\t"		\
-	"xchg %r14, regs+0x70\n\t"		\
-	"xchg %r15, regs+0x78\n\t"
-
-#define LOAD_GPR	SAVE_GPR
-
 #define SAVE_GPR_C				\
 	"xchg %%rax, regs\n\t"			\
 	"xchg %%rcx, regs+0x8\n\t"		\
diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c
index ff387ded..83d88480 100644
--- a/x86/vmx_tests.c
+++ b/x86/vmx_tests.c
@@ -11757,40 +11757,37 @@ static void vmx_cet_test(void)
 
 #define TEST(name) { #name, .v2 = name }
 
-/* name/init/guest_main/exit_handler/syscall_handler/guest_regs */
+/* name/init/guest_main/exit_handler/guest_regs */
 struct vmx_test vmx_tests[] = {
-	{ "null", NULL, basic_guest_main, basic_exit_handler, NULL, {0} },
-	{ "vmenter", NULL, vmenter_main, vmenter_exit_handler, NULL, {0} },
+	{ "null", NULL, basic_guest_main, basic_exit_handler, {0} },
+	{ "vmenter", NULL, vmenter_main, vmenter_exit_handler, {0} },
 	{ "preemption timer", preemption_timer_init, preemption_timer_main,
-		preemption_timer_exit_handler, NULL, {0} },
+		preemption_timer_exit_handler, {0} },
 	{ "control field PAT", test_ctrl_pat_init, test_ctrl_pat_main,
-		test_ctrl_pat_exit_handler, NULL, {0} },
+		test_ctrl_pat_exit_handler, {0} },
 	{ "control field EFER", test_ctrl_efer_init, test_ctrl_efer_main,
-		test_ctrl_efer_exit_handler, NULL, {0} },
+		test_ctrl_efer_exit_handler, {0} },
 	{ "CR shadowing", NULL, cr_shadowing_main,
-		cr_shadowing_exit_handler, NULL, {0} },
+		cr_shadowing_exit_handler, {0} },
 	{ "I/O bitmap", iobmp_init, iobmp_main, iobmp_exit_handler,
-		NULL, {0} },
+		{0} },
 	{ "instruction intercept", insn_intercept_init, insn_intercept_main,
-		insn_intercept_exit_handler, NULL, {0} },
-	{ "EPT A/D disabled", ept_init, ept_main, ept_exit_handler, NULL, {0} },
-	{ "EPT A/D enabled", eptad_init, eptad_main, eptad_exit_handler, NULL, {0} },
-	{ "PML", pml_init, pml_main, pml_exit_handler, NULL, {0} },
-	{ "interrupt", interrupt_init, interrupt_main,
-		interrupt_exit_handler, NULL, {0} },
-	{ "nmi_hlt", nmi_hlt_init, nmi_hlt_main,
-		nmi_hlt_exit_handler, NULL, {0} },
-	{ "debug controls", dbgctls_init, dbgctls_main, dbgctls_exit_handler,
-		NULL, {0} },
+		insn_intercept_exit_handler, {0} },
+	{ "EPT A/D disabled", ept_init, ept_main, ept_exit_handler, {0} },
+	{ "EPT A/D enabled", eptad_init, eptad_main, eptad_exit_handler, {0} },
+	{ "PML", pml_init, pml_main, pml_exit_handler, {0} },
+	{ "interrupt", interrupt_init, interrupt_main, interrupt_exit_handler, {0} },
+	{ "nmi_hlt", nmi_hlt_init, nmi_hlt_main, nmi_hlt_exit_handler, {0} },
+	{ "debug controls", dbgctls_init, dbgctls_main, dbgctls_exit_handler, {0} },
 	{ "MSR switch", msr_switch_init, msr_switch_main,
-		msr_switch_exit_handler, NULL, {0}, msr_switch_entry_failure },
-	{ "vmmcall", vmmcall_init, vmmcall_main, vmmcall_exit_handler, NULL, {0} },
+		msr_switch_exit_handler, {0}, msr_switch_entry_failure },
+	{ "vmmcall", vmmcall_init, vmmcall_main, vmmcall_exit_handler, {0} },
 	{ "disable RDTSCP", disable_rdtscp_init, disable_rdtscp_main,
-		disable_rdtscp_exit_handler, NULL, {0} },
+		disable_rdtscp_exit_handler, {0} },
 	{ "exit_monitor_from_l2_test", NULL, exit_monitor_from_l2_main,
-		exit_monitor_from_l2_handler, NULL, {0} },
+		exit_monitor_from_l2_handler, {0} },
 	{ "invalid_msr", invalid_msr_init, invalid_msr_main,
-		invalid_msr_exit_handler, NULL, {0}, invalid_msr_entry_failure},
+		invalid_msr_exit_handler, {0}, invalid_msr_entry_failure},
 	/* Basic V2 tests. */
 	TEST(v2_null_test),
 	TEST(v2_multiple_entries_test),
@@ -11876,5 +11873,5 @@ struct vmx_test vmx_tests[] = {
 	TEST(vmx_canonical_test),
 	/* "Load CET" VM-entry/exit controls tests. */
 	TEST(vmx_cet_test),
-	{ NULL, NULL, NULL, NULL, NULL, {0} },
+	{ NULL, NULL, NULL, NULL, {0} },
 };
-- 
2.54.0.563.g4f69b47b94-goog