Re: [PATCH 2/2] kvm-unit-tests: VMX: Test cases for nested EPT

Arthur Chunqi Li
2013-09-09T14:11:04Z

On Mon, Sep 9, 2013 at 9:56 PM, Paolo Bonzini <pbonzini@redhat.com> wrote:
> Il 09/09/2013 06:57, Arthur Chunqi Li ha scritto:
>> Some test cases for nested EPT features, including:
>> 1. EPT basic framework tests: read, write and remap.
>> 2. EPT misconfigurations test cases: page permission mieconfiguration
>> and memory type misconfiguration
>> 3. EPT violations test cases: page permission violation and paging
>> structure violation
>>
>> Signed-off-by: Arthur Chunqi Li <yzt356@gmail.com>
>> ---
>> x86/vmx_tests.c | 266 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
>> 1 file changed, 266 insertions(+)
>>
>> diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c
>> index c1b39f4..a0b9824 100644
>> --- a/x86/vmx_tests.c
>> +++ b/x86/vmx_tests.c
>> @@ -1,4 +1,36 @@
>> #include "vmx.h"
>> +#include "processor.h"
>> +#include "vm.h"
>> +#include "msr.h"
>> +#include "fwcfg.h"
>> +
>> +volatile u32 stage;
>> +volatile bool init_fail;
>
> Why volatile?
Because init_fail is only set but not used later in ept_init(), and if
I don't add volatile, compiler may optimize the setting to init_fail.

This occasion firstly occurred when I write set_stage/get_stage. If
one variant is set in a function but not used later, the compiler
usually optimizes this setting as redundant assignment and remove it.

Arthur
>
> The patch looks good.
>
>> +unsigned long *pml4;
>> +u64 eptp;
>> +void *data_page1, *data_page2;
>> +
>> +static inline void set_stage(u32 s)
>> +{
>> + barrier();
>> + stage = s;
>> + barrier();
>> +}
>> +
>> +static inline u32 get_stage()
>> +{
>> + u32 s;
>> +
>> + barrier();
>> + s = stage;
>> + barrier();
>> + return s;
>> +}
>> +
>> +static inline void vmcall()
>> +{
>> + asm volatile ("vmcall");
>> +}
>>
>> void basic_init()
>> {
>> @@ -76,6 +108,238 @@ int vmenter_exit_handler()
>> return VMX_TEST_VMEXIT;
>> }
>>
>> +static int setup_ept()
>> +{
>> + int support_2m;
>> + unsigned long end_of_memory;
>> +
>> + if (!(ept_vpid.val & EPT_CAP_UC) &&
>> + !(ept_vpid.val & EPT_CAP_WB)) {
>> + printf("\tEPT paging-structure memory type "
>> + "UC&WB are not supported\n");
>> + return 1;
>> + }
>> + if (ept_vpid.val & EPT_CAP_UC)
>> + eptp = EPT_MEM_TYPE_UC;
>> + else
>> + eptp = EPT_MEM_TYPE_WB;
>> + if (!(ept_vpid.val & EPT_CAP_PWL4)) {
>> + printf("\tPWL4 is not supported\n");
>> + return 1;
>> + }
>> + eptp |= (3 << EPTP_PG_WALK_LEN_SHIFT);
>> + pml4 = alloc_page();
>> + memset(pml4, 0, PAGE_SIZE);
>> + eptp |= virt_to_phys(pml4);
>> + vmcs_write(EPTP, eptp);
>> + support_2m = !!(ept_vpid.val & EPT_CAP_2M_PAGE);
>> + end_of_memory = fwcfg_get_u64(FW_CFG_RAM_SIZE);
>> + if (end_of_memory < (1ul << 32))
>> + end_of_memory = (1ul << 32);
>> + if (setup_ept_range(pml4, 0, end_of_memory,
>> + 0, support_2m, EPT_WA | EPT_RA | EPT_EA)) {
>> + printf("\tSet ept tables failed.\n");
>> + return 1;
>> + }
>> + return 0;
>> +}
>> +
>> +static void ept_init()
>> +{
>> + u32 ctrl_cpu[2];
>> +
>> + init_fail = false;
>> + ctrl_cpu[0] = vmcs_read(CPU_EXEC_CTRL0);
>> + ctrl_cpu[1] = vmcs_read(CPU_EXEC_CTRL1);
>> + ctrl_cpu[0] = (ctrl_cpu[0] | CPU_SECONDARY)
>> + & ctrl_cpu_rev[0].clr;
>> + ctrl_cpu[1] = (ctrl_cpu[1] | CPU_EPT)
>> + & ctrl_cpu_rev[1].clr;
>> + vmcs_write(CPU_EXEC_CTRL0, ctrl_cpu[0]);
>> + vmcs_write(CPU_EXEC_CTRL1, ctrl_cpu[1] | CPU_EPT);
>> + if (setup_ept())
>> + init_fail = true;
>> + data_page1 = alloc_page();
>> + data_page2 = alloc_page();
>> + memset(data_page1, 0x0, PAGE_SIZE);
>> + memset(data_page2, 0x0, PAGE_SIZE);
>> + *((u32 *)data_page1) = MAGIC_VAL_1;
>> + *((u32 *)data_page2) = MAGIC_VAL_2;
>> + install_ept(pml4, (unsigned long)data_page1, (unsigned long)data_page2,
>> + EPT_RA | EPT_WA | EPT_EA);
>> +}
>> +
>> +static void ept_main()
>> +{
>> + if (init_fail)
>> + return;
>> + if (!(ctrl_cpu_rev[0].clr & CPU_SECONDARY)
>> + && !(ctrl_cpu_rev[1].clr & CPU_EPT)) {
>> + printf("\tEPT is not supported");
>> + return;
>> + }
>> + set_stage(0);
>> + if (*((u32 *)data_page2) != MAGIC_VAL_1 &&
>> + *((u32 *)data_page1) != MAGIC_VAL_1)
>> + report("EPT basic framework - read", 0);
>> + else {
>> + *((u32 *)data_page2) = MAGIC_VAL_3;
>> + vmcall();
>> + if (get_stage() == 1) {
>> + if (*((u32 *)data_page1) == MAGIC_VAL_3 &&
>> + *((u32 *)data_page2) == MAGIC_VAL_2)
>> + report("EPT basic framework", 1);
>> + else
>> + report("EPT basic framework - remap", 1);
>> + }
>> + }
>> + // Test EPT Misconfigurations
>> + set_stage(1);
>> + vmcall();
>> + *((u32 *)data_page1) = MAGIC_VAL_1;
>> + if (get_stage() != 2) {
>> + report("EPT misconfigurations", 0);
>> + goto t1;
>> + }
>> + set_stage(2);
>> + vmcall();
>> + *((u32 *)data_page1) = MAGIC_VAL_1;
>> + if (get_stage() != 3) {
>> + report("EPT misconfigurations", 0);
>> + goto t1;
>> + }
>> + report("EPT misconfigurations", 1);
>> +t1:
>> + // Test EPT violation
>> + set_stage(3);
>> + vmcall();
>> + *((u32 *)data_page1) = MAGIC_VAL_1;
>> + if (get_stage() == 4)
>> + report("EPT violation - page permission", 1);
>> + else
>> + report("EPT violation - page permission", 0);
>> + // Violation caused by EPT paging structure
>> + set_stage(4);
>> + vmcall();
>> + *((u32 *)data_page1) = MAGIC_VAL_2;
>> + if (get_stage() == 5)
>> + report("EPT violation - paging structure", 1);
>> + else
>> + report("EPT violation - paging structure", 0);
>> + return;
>> +}
>> +
>> +static int ept_exit_handler()
>> +{
>> + u64 guest_rip;
>> + ulong reason;
>> + u32 insn_len;
>> + u32 exit_qual;
>> + static unsigned long data_page1_pte, data_page1_pte_pte;
>> +
>> + 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 (get_stage()) {
>> + case 0:
>> + if (*((u32 *)data_page1) == MAGIC_VAL_3 &&
>> + *((u32 *)data_page2) == MAGIC_VAL_2) {
>> + set_stage(get_stage() + 1);
>> + install_ept(pml4, (unsigned long)data_page2,
>> + (unsigned long)data_page2,
>> + EPT_RA | EPT_WA | EPT_EA);
>> + } else
>> + report("EPT basic framework - write\n", 0);
>> + break;
>> + case 1:
>> + install_ept(pml4, (unsigned long)data_page1,
>> + (unsigned long)data_page1, EPT_WA);
>> + invept(INVEPT_SINGLE, eptp);
>> + break;
>> + case 2:
>> + install_ept(pml4, (unsigned long)data_page1,
>> + (unsigned long)data_page1,
>> + EPT_RA | EPT_WA | EPT_EA |
>> + (2 << EPT_MEM_TYPE_SHIFT));
>> + invept(INVEPT_SINGLE, eptp);
>> + break;
>> + case 3:
>> + data_page1_pte = get_ept_pte(pml4,
>> + (unsigned long)data_page1, 1);
>> + set_ept_pte(pml4, (unsigned long)data_page1,
>> + 1, data_page1_pte & (~EPT_PRESENT));
>> + invept(INVEPT_SINGLE, eptp);
>> + break;
>> + case 4:
>> + data_page1_pte = get_ept_pte(pml4,
>> + (unsigned long)data_page1, 2);
>> + data_page1_pte &= PAGE_MASK;
>> + data_page1_pte_pte = get_ept_pte(pml4, data_page1_pte, 2);
>> + set_ept_pte(pml4, data_page1_pte, 2,
>> + data_page1_pte_pte & (~EPT_PRESENT));
>> + invept(INVEPT_SINGLE, eptp);
>> + break;
>> + // Should not reach here
>> + default:
>> + printf("ERROR - unknown stage, %d.\n", get_stage());
>> + print_vmexit_info();
>> + return VMX_TEST_VMEXIT;
>> + }
>> + vmcs_write(GUEST_RIP, guest_rip + insn_len);
>> + return VMX_TEST_RESUME;
>> + case VMX_EPT_MISCONFIG:
>> + switch (get_stage()) {
>> + case 1:
>> + case 2:
>> + set_stage(get_stage() + 1);
>> + install_ept(pml4, (unsigned long)data_page1,
>> + (unsigned long)data_page1,
>> + EPT_RA | EPT_WA | EPT_EA);
>> + invept(INVEPT_SINGLE, eptp);
>> + break;
>> + // Should not reach here
>> + default:
>> + printf("ERROR - unknown stage, %d.\n", get_stage());
>> + print_vmexit_info();
>> + return VMX_TEST_VMEXIT;
>> + }
>> + vmcs_write(GUEST_RIP, guest_rip + insn_len);
>> + return VMX_TEST_RESUME;
>> + case VMX_EPT_VIOLATION:
>> + switch(get_stage()) {
>> + case 3:
>> + if (exit_qual == (EPT_VLT_WR | EPT_VLT_LADDR_VLD |
>> + EPT_VLT_PADDR))
>> + set_stage(get_stage() + 1);
>> + set_ept_pte(pml4, (unsigned long)data_page1,
>> + 1, data_page1_pte | (EPT_PRESENT));
>> + invept(INVEPT_SINGLE, eptp);
>> + break;
>> + case 4:
>> + if (exit_qual == (EPT_VLT_RD | EPT_VLT_LADDR_VLD))
>> + set_stage(get_stage() + 1);
>> + set_ept_pte(pml4, data_page1_pte, 2,
>> + data_page1_pte_pte | (EPT_PRESENT));
>> + invept(INVEPT_SINGLE, eptp);
>> + break;
>> + default:
>> + // Should not reach here
>> + printf("ERROR : unknown stage, %d\n", get_stage());
>> + print_vmexit_info();
>> + return VMX_TEST_VMEXIT;
>> + }
>> + 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[] = {
>> @@ -83,5 +347,7 @@ struct vmx_test vmx_tests[] = {
>> basic_syscall_handler, {0} },
>> { "vmenter", basic_init, vmenter_main, vmenter_exit_handler,
>> basic_syscall_handler, {0} },
>> + { "EPT framework", ept_init, ept_main, ept_exit_handler,
>> + basic_syscall_handler, {0} },
>> { NULL, NULL, NULL, NULL, NULL, {0} },
>> };
>>
>