linux-kernel - gdb switches to __sysvec_apic_timer_interrupt or __default_send_IPI_dest

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Date:   Sat, 29 Jan 2022 23:06:48 +0200
From:   Vasyl Vavrychuk <vvavrychuk@...il.com>
To:     qemu-discuss@...gnu.org, linux-kernel@...r.kernel.org,
        gdb@...rceware.org
Subject: gdb switches to __sysvec_apic_timer_interrupt or __default_send_IPI_dest_field
 with KVM enabled

Hello,

I run Linux kernel under qemu-system-x86_64 via the "-kernel" option.

Also, I added the "-s" option to accept the gdb connection.

After Linux boot up I connect with gdb and set a breakpoint in some
function, for example "device_del", does not matter really.

The problem is if I also use "--enable-kvm", then after breakpoint
triggered and sending "n" from gdb, it switches to

    __sysvec_apic_timer_interrupt (regs=0xffffc90000297de8) at
arch/x86/kernel/apic/apic.c:1102
    1102            trace_local_timer_entry(LOCAL_TIMER_VECTOR);

or to

    __default_send_IPI_dest_field (mask=<optimized out>,
vector=<optimized out>, dest=dest@...ry=2048) at
arch/x86/kernel/apic/ipi.c:161
    161             cfg = __prepare_ICR2(mask);

I am stepping over kernel code that does not perform any waiting or blocking.

Everything works fine with "--enable-kvm" removed.

Thanks,
Vasyl