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

Arthur Chunqi Li
2013-09-09T15:29:24Z

On Mon, Sep 9, 2013 at 12:57 PM, Arthur Chunqi Li <yzt356@gmail.com> wrote:
> 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;
> +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);
Hi Paolo,
I noticed another possible bug of this patch. Stage 4 of this patch
test the scenario that the page of a paging structure is not present,
then this will cause EPT violation vmexit with bit 8 of exit_qual
unset. My question is: will instruction length be correctly set on
this scenario? I got wrong insn_len in "case 4" of VMX_EPT_VIOLATION,
which may cause triple fault vmexit.
> + 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} },
> };
> --
> 1.7.9.5
>