On Fri, Dec 05, 2025 at 10:23:42AM -0800, Sean Christopherson wrote:
On Wed, Sep 10, 2025, Hou Wenlong wrote:
#define IRQ_VECTOR 0xAA +#define CAST_TO_RIP(v) ((unsigned long long)&(v))
/* For testing data access debug BP */ uint32_t guest_value; extern unsigned char sw_bp, hw_bp, write_data, ss_start, bd_start; -extern unsigned char fep_bd_start; +extern unsigned char fep_bd_start, fep_sti_start, fep_sti_end;
+static void guest_db_handler(struct ex_regs *regs) +{
- static int count;
- unsigned long target_rips[2] = {
CAST_TO_RIP(fep_sti_start),CAST_TO_RIP(fep_sti_end),- };
- __GUEST_ASSERT(regs->rip == target_rips[count], "STI: unexpected rip 0x%lx (should be 0x%lx)",
regs->rip, target_rips[count]);- regs->rflags &= ~X86_EFLAGS_TF;
- count++;
+}
+static void guest_irq_handler(struct ex_regs *regs) +{ +} static void guest_code(void) { @@ -69,13 +89,25 @@ static void guest_code(void) if (is_forced_emulation_enabled) { /* DR6.BD test for emulation */ asm volatile(KVM_FEP "fep_bd_start: mov %%dr0, %%rax" : : : "rax");
/* pending debug exceptions for emulation */asm volatile("pushf\n\t""orq $" __stringify(X86_EFLAGS_TF) ", (%rsp)\n\t""popf\n\t""sti\n\t""fep_sti_start:""cli\n\t""pushf\n\t""orq $" __stringify(X86_EFLAGS_TF) ", (%rsp)\n\t""popf\n\t"KVM_FEP "sti\n\t""fep_sti_end:""cli\n\t");GUEST_DONE(); } -#define CAST_TO_RIP(v) ((unsigned long long)&(v))
static void vcpu_skip_insn(struct kvm_vcpu *vcpu, int insn_len) { struct kvm_regs regs; @@ -110,6 +142,9 @@ int main(void) vm = vm_create_with_one_vcpu(&vcpu, guest_code); run = vcpu->run;
- vm_install_exception_handler(vm, DB_VECTOR, guest_db_handler);
- vm_install_exception_handler(vm, IRQ_VECTOR, guest_irq_handler);
But the IRQ should never be taken thanks to the CLI in the STI shadow. I.e. installing a dummy handler could mask failures, no?
Yes, this also breaks the testcase regarding KVM_GUESTDBG_BLOCKIRQ. Sorry, I forgot why I added this, as you said there should be no IRQ delivered due to the STI shadow. :( I'll remove it in the next version.
Thanks!
- /* Test software BPs - int3 */ memset(&debug, 0, sizeof(debug)); debug.control = KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP;
-- 2.31.1