Re: [PATCH 2/4] kvm-unit-tests: VMX: Add test cases for CR0/4 shadowing

[Jan Kiszka <jan.kiszka@web.de>]

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On 2013-08-13 17:56, Arthur Chunqi Li wrote:
> Add testing for CR0/4 shadowing.

A few sentences on the test strategy would be good.

> 
> Signed-off-by: Arthur Chunqi Li <yzt356@gmail.com>
> ---
>  lib/x86/vm.h    |    4 +
>  x86/vmx_tests.c |  218 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 222 insertions(+)
> 
> diff --git a/lib/x86/vm.h b/lib/x86/vm.h
> index eff6f72..6e0ce2b 100644
> --- a/lib/x86/vm.h
> +++ b/lib/x86/vm.h
> @@ -17,9 +17,13 @@
>  #define PTE_ADDR    (0xffffffffff000ull)
>  
>  #define X86_CR0_PE      0x00000001
> +#define X86_CR0_MP      0x00000002
> +#define X86_CR0_TS      0x00000008
>  #define X86_CR0_WP      0x00010000
>  #define X86_CR0_PG      0x80000000
>  #define X86_CR4_VMXE   0x00000001
> +#define X86_CR4_TSD     0x00000004
> +#define X86_CR4_DE      0x00000008
>  #define X86_CR4_PSE     0x00000010
>  #define X86_CR4_PAE     0x00000020
>  #define X86_CR4_PCIDE  0x00020000
> diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c
> index 61b0cef..44be3f4 100644
> --- a/x86/vmx_tests.c
> +++ b/x86/vmx_tests.c
> @@ -5,12 +5,18 @@
>  
>  u64 ia32_pat;
>  u64 ia32_efer;
> +u32 stage;
>  
>  static inline void vmcall()
>  {
>  	asm volatile("vmcall");
>  }
>  
> +static inline void set_stage(u32 s)
> +{
> +	asm volatile("mov %0, stage\n\t"::"r"(s):"memory", "cc");
> +}
> +

Why do we need "state = s" as assembler instruction?

>  void basic_init()
>  {
>  }
> @@ -257,6 +263,216 @@ static int test_ctrl_efer_exit_handler()
>  	return VMX_TEST_VMEXIT;
>  }
>  
> +u32 guest_cr0, guest_cr4;
> +
> +static void cr_shadowing_main()
> +{
> +	u32 cr0, cr4, tmp;
> +
> +	// Test read through
> +	set_stage(0);
> +	guest_cr0 = read_cr0();
> +	if (stage == 1)
> +		report("Read through CR0", 0);
> +	else
> +		vmcall();
> +	set_stage(1);
> +	guest_cr4 = read_cr4();
> +	if (stage == 2)
> +		report("Read through CR4", 0);
> +	else
> +		vmcall();
> +	// Test write through
> +	guest_cr0 = guest_cr0 ^ (X86_CR0_TS | X86_CR0_MP);
> +	guest_cr4 = guest_cr4 ^ (X86_CR4_TSD | X86_CR4_DE);
> +	set_stage(2);
> +	write_cr0(guest_cr0);
> +	if (stage == 3)
> +		report("Write throuth CR0", 0);
> +	else
> +		vmcall();
> +	set_stage(3);
> +	write_cr4(guest_cr4);
> +	if (stage == 4)
> +		report("Write through CR4", 0);
> +	else
> +		vmcall();
> +	// Test read shadow
> +	set_stage(4);
> +	vmcall();
> +	cr0 = read_cr0();
> +	if (stage != 5) {
> +		if (cr0 == guest_cr0)
> +			report("Read shadowing CR0", 1);
> +		else
> +			report("Read shadowing CR0", 0);
> +	}
> +	set_stage(5);
> +	cr4 = read_cr4();
> +	if (stage != 6) {
> +		if (cr4 == guest_cr4)
> +			report("Read shadowing CR4", 1);
> +		else
> +			report("Read shadowing CR4", 0);
> +	}
> +	// Test write shadow (same value with shadow)
> +	set_stage(6);
> +	write_cr0(guest_cr0);
> +	if (stage == 7)
> +		report("Write shadowing CR0 (same value with shadow)", 0);
> +	else
> +		vmcall();
> +	set_stage(7);
> +	write_cr4(guest_cr4);
> +	if (stage == 8)
> +		report("Write shadowing CR4 (same value with shadow)", 0);
> +	else
> +		vmcall();
> +	// Test write shadow (different value)
> +	set_stage(8);
> +	tmp = guest_cr0 ^ X86_CR0_TS;
> +	asm volatile("mov %0, %%rsi\n\t"
> +		"mov %%rsi, %%cr0\n\t"
> +		::"m"(tmp)
> +		:"rsi", "memory", "cc");
> +	if (stage != 9)
> +		report("Write shadowing different X86_CR0_TS", 0);
> +	else
> +		report("Write shadowing different X86_CR0_TS", 1);
> +	set_stage(9);
> +	tmp = guest_cr0 ^ X86_CR0_MP;
> +	asm volatile("mov %0, %%rsi\n\t"
> +		"mov %%rsi, %%cr0\n\t"
> +		::"m"(tmp)
> +		:"rsi", "memory", "cc");
> +	if (stage != 10)
> +		report("Write shadowing different X86_CR0_MP", 0);
> +	else
> +		report("Write shadowing different X86_CR0_MP", 1);
> +	set_stage(10);
> +	tmp = guest_cr4 ^ X86_CR4_TSD;
> +	asm volatile("mov %0, %%rsi\n\t"
> +		"mov %%rsi, %%cr4\n\t"
> +		::"m"(tmp)
> +		:"rsi", "memory", "cc");
> +	if (stage != 11)
> +		report("Write shadowing different X86_CR4_TSD", 0);
> +	else
> +		report("Write shadowing different X86_CR4_TSD", 1);
> +	set_stage(11);
> +	tmp = guest_cr4 ^ X86_CR4_DE;
> +	asm volatile("mov %0, %%rsi\n\t"
> +		"mov %%rsi, %%cr4\n\t"
> +		::"m"(tmp)
> +		:"rsi", "memory", "cc");
> +	if (stage != 12)
> +		report("Write shadowing different X86_CR4_DE", 0);
> +	else
> +		report("Write shadowing different X86_CR4_DE", 1);
> +}
> +
> +static int cr_shadowing_exit_handler()
> +{
> +	u64 guest_rip;
> +	ulong reason;
> +	u32 insn_len;
> +	u32 exit_qual;
> +
> +	guest_rip = vmcs_read(GUEST_RIP);
> +	reason = vmcs_read(EXI_REASON) & 0xff;
> +	insn_len = vmcs_read(EXI_INST_LEN);
> +	exit_qual = vmcs_read(EXI_QUALIFICATION);
> +	switch (reason) {
> +	case VMX_VMCALL:
> +		switch (stage) {
> +		case 0:
> +			if (guest_cr0 == vmcs_read(GUEST_CR0))
> +				report("Read through CR0", 1);
> +			else
> +				report("Read through CR0", 0);
> +			break;
> +		case 1:
> +			if (guest_cr4 == vmcs_read(GUEST_CR4))
> +				report("Read through CR4", 1);
> +			else
> +				report("Read through CR4", 0);
> +			break;
> +		case 2:
> +			if (guest_cr0 == vmcs_read(GUEST_CR0))
> +				report("Write through CR0", 1);
> +			else
> +				report("Write through CR0", 0);
> +			break;
> +		case 3:
> +			if (guest_cr4 == vmcs_read(GUEST_CR4))
> +				report("Write through CR4", 1);
> +			else
> +				report("Write through CR4", 0);
> +			break;
> +		case 4:
> +			guest_cr0 = vmcs_read(GUEST_CR0) ^ (X86_CR0_TS | X86_CR0_MP);
> +			guest_cr4 = vmcs_read(GUEST_CR4) ^ (X86_CR4_TSD | X86_CR4_DE);
> +			vmcs_write(CR0_MASK, X86_CR0_TS | X86_CR0_MP);
> +			vmcs_write(CR0_READ_SHADOW, guest_cr0 & (X86_CR0_TS | X86_CR0_MP));
> +			vmcs_write(CR4_MASK, X86_CR4_TSD | X86_CR4_DE);
> +			vmcs_write(CR4_READ_SHADOW, guest_cr4 & (X86_CR4_TSD | X86_CR4_DE));
> +			break;
> +		case 6:
> +			if (guest_cr0 == (vmcs_read(GUEST_CR0) ^ (X86_CR0_TS | X86_CR0_MP)))
> +				report("Write shadowing CR0 (same value)", 1);
> +			else
> +				report("Write shadowing CR0 (same value)", 0);
> +			break;
> +		case 7:
> +			if (guest_cr4 == (vmcs_read(GUEST_CR4) ^ (X86_CR4_TSD | X86_CR4_DE)))
> +				report("Write shadowing CR4 (same value)", 1);
> +			else
> +				report("Write shadowing CR4 (same value)", 0);
> +			break;
> +		default:

report("something went wrong", 0); ???

> +			break;
> +		}
> +		vmcs_write(GUEST_RIP, guest_rip + insn_len);
> +		return VMX_TEST_RESUME;
> +	case VMX_CR:
> +		switch (stage) {
> +		case 4:
> +			report("Read shadowing CR0", 0);
> +			set_stage(stage + 1);
> +			break;
> +		case 5:
> +			report("Read shadowing CR4", 0);
> +			set_stage(stage + 1);
> +			break;
> +		case 6:
> +			report("Write shadowing CR0 (same value)", 0);
> +			set_stage(stage + 1);
> +			break;
> +		case 7:
> +			report("Write shadowing CR4 (same value)", 0);
> +			set_stage(stage + 1);
> +			break;
> +		case 8:
> +		case 9:
> +			if (exit_qual == 0x600)
> +				set_stage(stage + 1);

What is this qualification about? Yes, ESI to CR0, but that takes a
manual to find out. And what if exit_qual is something else? Is that a
test error?

> +			break;
> +		case 10:
> +		case 11:
> +			if (exit_qual == 0x604)
> +				set_stage(stage + 1);

Same as above.

> +		default:

...?

> +			break;
> +		}
> +		vmcs_write(GUEST_RIP, guest_rip + insn_len);
> +		return VMX_TEST_RESUME;
> +	default:
> +		printf("Unknown exit reason, %d\n", reason);
> +		print_vmexit_info();
> +	}
> +	return VMX_TEST_VMEXIT;
> +}
> +
>  /* name/init/guest_main/exit_handler/syscall_handler/guest_regs
>     basic_* just implement some basic functions */
>  struct vmx_test vmx_tests[] = {
> @@ -268,5 +484,7 @@ struct vmx_test vmx_tests[] = {
>  		test_ctrl_pat_exit_handler, basic_syscall_handler, {0} },
>  	{ "control field EFER", test_ctrl_efer_init, test_ctrl_efer_main,
>  		test_ctrl_efer_exit_handler, basic_syscall_handler, {0} },
> +	{ "CR shadowing", basic_init, cr_shadowing_main,
> +		cr_shadowing_exit_handler, basic_syscall_handler, {0} },
>  	{ NULL, NULL, NULL, NULL, NULL, {0} },
>  };
> 

Jan


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