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

Paolo Bonzini
2021-09-06T11:20:28Z

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.

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);
>