Re: [PATCH 5/5] VMX: Test behavior on set and cleared save/load debug controls

[Paolo Bonzini <pbonzini@redhat.com>]

Il 15/06/2014 16:24, Jan Kiszka ha scritto:
> From: Jan Kiszka <jan.kiszka@siemens.com>
> 
> This particularly checks the case when debug controls are not to be
> loaded/saved on host-guest transitions.
> 
> We have to fake results related to IA32_DEBUGCTL as support for this MSR
> is missing KVM. The test already contains all bits required once KVM
> adds support.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
>  x86/vmx.h       |   2 ++
>  x86/vmx_tests.c | 110 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 112 insertions(+)
> 
> diff --git a/x86/vmx.h b/x86/vmx.h
> index 38ec3c5..3c4830f 100644
> --- a/x86/vmx.h
> +++ b/x86/vmx.h
> @@ -326,6 +326,7 @@ enum Reason {
>  #define X86_EFLAGS_ZF	0x00000040 /* Zero Flag */
>  
>  enum Ctrl_exi {
> +	EXI_SAVE_DBGCTLS	= 1UL << 2,
>  	EXI_HOST_64             = 1UL << 9,
>  	EXI_LOAD_PERF		= 1UL << 12,
>  	EXI_INTA                = 1UL << 15,
> @@ -337,6 +338,7 @@ enum Ctrl_exi {
>  };
>  
>  enum Ctrl_ent {
> +	ENT_LOAD_DBGCTLS	= 1UL << 2,
>  	ENT_GUEST_64            = 1UL << 9,
>  	ENT_LOAD_PAT		= 1UL << 14,
>  	ENT_LOAD_EFER           = 1UL << 15,
> diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c
> index d0b67de..0f4cfc2 100644
> --- a/x86/vmx_tests.c
> +++ b/x86/vmx_tests.c
> @@ -1406,6 +1406,114 @@ static int interrupt_exit_handler(void)
>  	return VMX_TEST_VMEXIT;
>  }
>  
> +static int dbgctls_init(struct vmcs *vmcs)
> +{
> +	u64 dr7 = 0x402;
> +	u64 zero = 0;
> +
> +	msr_bmp_init();
> +	asm volatile(
> +		"mov %0,%%dr0\n\t"
> +		"mov %0,%%dr1\n\t"
> +		"mov %0,%%dr2\n\t"
> +		"mov %1,%%dr7\n\t"
> +		: : "r" (zero), "r" (dr7));
> +	wrmsr(MSR_IA32_DEBUGCTLMSR, 0x1);
> +	vmcs_write(GUEST_DR7, 0x404);
> +	vmcs_write(GUEST_DEBUGCTL, 0x2);
> +
> +	vmcs_write(ENT_CONTROLS, vmcs_read(ENT_CONTROLS) | ENT_LOAD_DBGCTLS);
> +	vmcs_write(EXI_CONTROLS, vmcs_read(EXI_CONTROLS) | EXI_SAVE_DBGCTLS);
> +
> +	return VMX_TEST_START;
> +}
> +
> +static void dbgctls_main(void)
> +{
> +	u64 dr7, debugctl;
> +
> +	asm volatile("mov %%dr7,%0" : "=r" (dr7));
> +	debugctl = rdmsr(MSR_IA32_DEBUGCTLMSR);
> +	debugctl = 0x2; /* KVM does not support DEBUGCTL so far */
> +	report("Load debug controls", dr7 == 0x404 && debugctl == 0x2);

Please comment instead like this:

	report("Load debug controls", dr7 == 0x404 /* && debugctl == 0x2 */ );

> +	asm volatile("mov %%dr7,%0" : "=r" (dr7));
> +	debugctl = rdmsr(MSR_IA32_DEBUGCTLMSR);
> +	debugctl = 0x1; /* no KVM support */
> +	report("Guest=host debug controls", dr7 == 0x402 && debugctl == 0x1);

Same here.

> +			if (dr7 == 0x400 && debugctl == 0 &&
> +			    vmcs_read(GUEST_DR7) == 0x408 &&
> +			    vmcs_read(GUEST_DEBUGCTL) == /* 0x3 no KVM support*/ 0x2)

and here.

> +				set_stage(1);
> +			break;
> +		case 2:
> +			dr7 = 0x402;
> +			asm volatile("mov %0,%%dr7" : : "r" (dr7));
> +			wrmsr(MSR_IA32_DEBUGCTLMSR, 0x1);
> +			vmcs_write(GUEST_DR7, 0x404);
> +			vmcs_write(GUEST_DEBUGCTL, 0x2);
> +
> +			vmcs_write(ENT_CONTROLS,
> +				vmcs_read(ENT_CONTROLS) & ~ENT_LOAD_DBGCTLS);
> +			vmcs_write(EXI_CONTROLS,
> +				vmcs_read(EXI_CONTROLS) & ~EXI_SAVE_DBGCTLS);
> +			break;
> +		case 3:
> +			if (dr7 == 0x400 && debugctl == 0 &&
> +			    vmcs_read(GUEST_DR7) == 0x404 &&
> +			    vmcs_read(GUEST_DEBUGCTL) == 0x2)

and here too, even though it happens to work.

Paolo

> +				set_stage(4);
> +			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 */
>  struct vmx_test vmx_tests[] = {
>  	{ "null", NULL, basic_guest_main, basic_exit_handler, NULL, {0} },
> @@ -1425,5 +1533,7 @@ struct vmx_test vmx_tests[] = {
>  	{ "EPT framework", ept_init, ept_main, ept_exit_handler, NULL, {0} },
>  	{ "interrupt", interrupt_init, interrupt_main,
>  		interrupt_exit_handler, NULL, {0} },
> +	{ "debug controls", dbgctls_init, dbgctls_main, dbgctls_exit_handler,
> +		NULL, {0} },
>  	{ NULL, NULL, NULL, NULL, NULL, {0} },
>  };
>