On Fri, Feb 7, 2020 at 2:36 AM Oliver Upton <oupton@xxxxxxxxxx> wrote:
>
> Test to verify that MTF VM-exits into host are synthesized when the
> 'monitor trap flag' processor-based VM-execution control is set under
> various conditions.
>
> Expect an MTF VM-exit if instruction execution produces no events other
> than MTF. Should instruction execution produce a concurrent debug-trap
> and MTF event, expect an MTF VM-exit with the 'pending debug exceptions'
> VMCS field set. Expect an MTF VM-exit to follow event delivery should
> instruction execution generate a higher-priority event, such as a
> general-protection fault. Lastly, expect an MTF VM-exit to follow
> delivery of a debug-trap software exception (INT1/INT3/INTO/INT n).
>
> Signed-off-by: Oliver Upton <oupton@xxxxxxxxxx>
> Reviewed-by: Jim Mattson <jmattson@xxxxxxxxxx>
> ---
> x86/vmx.h | 1 +
> x86/vmx_tests.c | 157 ++++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 158 insertions(+)
>
> diff --git a/x86/vmx.h b/x86/vmx.h
> index 6214400f2b53..6adf0916564b 100644
> --- a/x86/vmx.h
> +++ b/x86/vmx.h
> @@ -399,6 +399,7 @@ enum Ctrl0 {
> CPU_NMI_WINDOW = 1ul << 22,
> CPU_IO = 1ul << 24,
> CPU_IO_BITMAP = 1ul << 25,
> + CPU_MTF = 1ul << 27,
> CPU_MSR_BITMAP = 1ul << 28,
> CPU_MONITOR = 1ul << 29,
> CPU_PAUSE = 1ul << 30,
> diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c
> index b31c360c5f3c..0e2c2f8a7d34 100644
> --- a/x86/vmx_tests.c
> +++ b/x86/vmx_tests.c
> @@ -4970,6 +4970,162 @@ static void test_vmx_preemption_timer(void)
> vmcs_write(EXI_CONTROLS, saved_exit);
> }
>
> +extern unsigned char test_mtf1;
> +extern unsigned char test_mtf2;
> +extern unsigned char test_mtf3;
> +
> +__attribute__((noclone)) static void test_mtf_guest(void)
> +{
> + asm ("vmcall;\n\t"
> + "out %al, $0x80;\n\t"
> + "test_mtf1:\n\t"
> + "vmcall;\n\t"
> + "out %al, $0x80;\n\t"
> + "test_mtf2:\n\t"
> + /*
> + * Prepare for the 'MOV CR3' test. Attempt to induce a
> + * general-protection fault by moving a non-canonical address into
> + * CR3. The 'MOV CR3' instruction does not take an imm64 operand,
> + * so we must MOV the desired value into a register first.
> + *
> + * MOV RAX is done before the VMCALL such that MTF is only enabled
> + * for the instruction under test.
> + */
> + "mov $0x8000000000000000, %rax;\n\t"
> + "vmcall;\n\t"
> + "mov %rax, %cr3;\n\t"
> + "test_mtf3:\n\t"
> + "vmcall;\n\t"
> + /*
> + * ICEBP/INT1 instruction. Though the instruction is now
> + * documented, don't rely on assemblers enumerating the
> + * instruction. Resort to hand assembly.
> + */
> + ".byte 0xf1;\n\t");
> +}
> +
> +static void test_mtf_gp_handler(struct ex_regs *regs)
> +{
> + regs->rip = (unsigned long) &test_mtf3;
> +}
> +
> +static void test_mtf_db_handler(struct ex_regs *regs)
> +{
> +}
> +
> +static void enable_mtf(void)
> +{
> + u32 ctrl0 = vmcs_read(CPU_EXEC_CTRL0);
> +
> + vmcs_write(CPU_EXEC_CTRL0, ctrl0 | CPU_MTF);
> +}
> +
> +static void disable_mtf(void)
> +{
> + u32 ctrl0 = vmcs_read(CPU_EXEC_CTRL0);
> +
> + vmcs_write(CPU_EXEC_CTRL0, ctrl0 & ~CPU_MTF);
> +}
> +
> +static void enable_tf(void)
> +{
> + unsigned long rflags = vmcs_read(GUEST_RFLAGS);
> +
> + vmcs_write(GUEST_RFLAGS, rflags | X86_EFLAGS_TF);
> +}
> +
> +static void disable_tf(void)
> +{
> + unsigned long rflags = vmcs_read(GUEST_RFLAGS);
> +
> + vmcs_write(GUEST_RFLAGS, rflags & ~X86_EFLAGS_TF);
> +}
> +
> +static void report_mtf(const char *insn_name, unsigned long exp_rip)
> +{
> + unsigned long rip = vmcs_read(GUEST_RIP);
> +
> + assert_exit_reason(VMX_MTF);
> + report(rip == exp_rip, "MTF VM-exit after %s instruction. RIP: 0x%lx (expected 0x%lx)",
> + insn_name, rip, exp_rip);
> +}
> +
> +static void vmx_mtf_test(void)
> +{
> + unsigned long pending_dbg;
> + handler old_gp, old_db;
> +
> + if (!(ctrl_cpu_rev[0].clr & CPU_MTF)) {
> + printf("CPU does not support the 'monitor trap flag' processor-based VM-execution control.\n");
> + return;
> + }
> +
> + test_set_guest(test_mtf_guest);
> +
> + /* Expect an MTF VM-exit after OUT instruction */
> + enter_guest();
> + skip_exit_vmcall();
> +
> + enable_mtf();
> + enter_guest();
> + report_mtf("OUT", (unsigned long) &test_mtf1);
> + disable_mtf();
> +
> + /*
> + * Concurrent #DB trap and MTF on instruction boundary. Expect MTF
> + * VM-exit with populated 'pending debug exceptions' VMCS field.
> + */
> + enter_guest();
> + skip_exit_vmcall();
> +
> + enable_mtf();
> + enable_tf();
> +
> + enter_guest();
> + report_mtf("OUT", (unsigned long) &test_mtf2);
> + pending_dbg = vmcs_read(GUEST_PENDING_DEBUG);
> + report(pending_dbg & DR_STEP,
> + "'pending debug exceptions' field after MTF VM-exit: 0x%lx (expected 0x%lx)",
> + pending_dbg, (unsigned long) DR_STEP);
> +
> + disable_mtf();
> + disable_tf();
> + vmcs_write(GUEST_PENDING_DEBUG, 0);
> +
> + /*
> + * #GP exception takes priority over MTF. Expect MTF VM-exit with RIP
> + * advanced to first instruction of #GP handler.
> + */
> + enter_guest();
> + skip_exit_vmcall();
> +
> + old_gp = handle_exception(GP_VECTOR, test_mtf_gp_handler);
> +
> + enable_mtf();
> + enter_guest();
> + report_mtf("MOV CR3", (unsigned long) get_idt_addr(&boot_idt[GP_VECTOR]));
> + disable_mtf();
> +
> + /*
> + * Concurrent MTF and privileged software exception (i.e. ICEBP/INT1).
> + * MTF should follow the delivery of #DB trap, though the SDM doesn't
> + * provide clear indication of the relative priority.
> + */
> + enter_guest();
> + skip_exit_vmcall();
> +
> + handle_exception(GP_VECTOR, old_gp);
> + old_db = handle_exception(DB_VECTOR, test_mtf_db_handler);
> +
> + enable_mtf();
> + enter_guest();
> + report_mtf("INT1", (unsigned long) get_idt_addr(&boot_idt[DB_VECTOR]));
> + disable_mtf();
> +
> + enter_guest();
> + handle_exception(DB_VECTOR, old_db);
> +}
> +
> /*
> * Tests for VM-execution control fields
> */
> @@ -9505,5 +9661,6 @@ struct vmx_test vmx_tests[] = {
> TEST(atomic_switch_max_msrs_test),
> TEST(atomic_switch_overflow_msrs_test),
> TEST(rdtsc_vmexit_diff_test),
> + TEST(vmx_mtf_test),
> { NULL, NULL, NULL, NULL, NULL, {0} },
> };
> --
> 2.25.0.341.g760bfbb309-goog
>
Friendly ping :) (Just on this patch, 1-4 have already been applied)
--
Thanks,
Oliver
