Re: [PATCH v3 6/6] KVM: selftests: test KVM_GUESTDBG_BLOCKIRQ

Paolo Bonzini pbonzini@redhat.com writes:

On 11/08/21 14:29, Maxim Levitsky wrote:

...

Modify debug_regs test to create a pending interrupt and see that it is blocked when single stepping is done with KVM_GUESTDBG_BLOCKIRQ

Signed-off-by: Maxim Levitsky mlevitsk@redhat.com

.../testing/selftests/kvm/x86_64/debug_regs.c | 24 ++++++++++++++++--- 1 file changed, 21 insertions(+), 3 deletions(-)

I haven't looked very much at this, but the test fails.

Same here,

the test passes on AMD but fails consistently on Intel:

# ./x86_64/debug_regs ==== Test Assertion Failure ==== x86_64/debug_regs.c:179: run->exit_reason == KVM_EXIT_DEBUG && run->debug.arch.exception == DB_VECTOR && run->debug.arch.pc == target_rip && run->debug.arch.dr6 == target_dr6 pid=13434 tid=13434 errno=0 - Success 1 0x00000000004027c6: main at debug_regs.c:179 2 0x00007f65344cf554: ?? ??:0 3 0x000000000040294a: _start at ??:? SINGLE_STEP[1]: exit 8 exception 1 rip 0x402a25 (should be 0x402a27) dr6 0xffff4ff0 (should be 0xffff4ff0)

(I know I'm late to the party).

Paolo

...

diff --git a/tools/testing/selftests/kvm/x86_64/debug_regs.c b/tools/testing/selftests/kvm/x86_64/debug_regs.c index 6097a8283377..5f078db1bcba 100644 --- a/tools/testing/selftests/kvm/x86_64/debug_regs.c +++ b/tools/testing/selftests/kvm/x86_64/debug_regs.c @@ -8,12 +8,15 @@ #include <string.h> #include "kvm_util.h" #include "processor.h" +#include "apic.h" #define VCPU_ID 0 #define DR6_BD (1 << 13) #define DR7_GD (1 << 13) +#define IRQ_VECTOR 0xAA

• /* For testing data access debug BP */ uint32_t guest_value;

@@ -21,6 +24,11 @@ extern unsigned char sw_bp, hw_bp, write_data, ss_start, bd_start; static void guest_code(void) {

• /* Create a pending interrupt on current vCPU */
• x2apic_enable();
• x2apic_write_reg(APIC_ICR, APIC_DEST_SELF | APIC_INT_ASSERT |

• 	 APIC_DM_FIXED | IRQ_VECTOR);
  

• /*
  • Software BP tests.

@@ -38,12 +46,19 @@ static void guest_code(void) "mov %%rax,%0;\n\t write_data:" : "=m" (guest_value) : : "rax");

• /* Single step test, covers 2 basic instructions and 2 emulated */

• /*

• * Single step test, covers 2 basic instructions and 2 emulated
  

• *
  

• * Enable interrupts during the single stepping to see that
  

• * pending interrupt we raised is not handled due to KVM_GUESTDBG_BLOCKIRQ
  

• */
  

  asm volatile("ss_start: "

•      "sti\n\t"
  "xor %%eax,%%eax\n\t"
  "cpuid\n\t"
  "movl $0x1a0,%%ecx\n\t"
  "rdmsr\n\t"
  

•      "cli\n\t"
  : : : "eax", "ebx", "ecx", "edx");
  

/* DR6.BD test */ @@ -72,11 +87,13 @@ int main(void) uint64_t cmd; int i; /* Instruction lengths starting at ss_start */

• int ss_size[4] = {

• int ss_size[6] = {

• 1,		/* sti*/
  

  2, /* xor */ 2, /* cpuid */ 5, /* mov */ 2, /* rdmsr */

• 1,		/* cli */
  

  };

if (!kvm_check_cap(KVM_CAP_SET_GUEST_DEBUG)) { @@ -154,7 +171,8 @@ int main(void) for (i = 0; i < (sizeof(ss_size) / sizeof(ss_size[0])); i++) { target_rip += ss_size[i]; CLEAR_DEBUG();

• debug.control = KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_SINGLESTEP;
  

• debug.control = KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_SINGLESTEP |
  

• 		KVM_GUESTDBG_BLOCKIRQ;
  

  debug.arch.debugreg[7] = 0x00000400; APPLY_DEBUG(); vcpu_run(vm, VCPU_ID);