https://bugzilla.kernel.org/show_bug.cgi?id=65561 --- Comment #17 from Jidong Xiao <jidong.xiao@xxxxxxxxx> --- Hi,Paolo, I am not familiar with kvm-unit-tests, and I cannot find any documents describe it. So I use gdb to debug. And yes I can reproduce the problem. I just use Jatin's sample code to construct a c program, like this: linux:~/code/cvedr # cat ss.c #include <stdio.h> main(){ asm __volatile__( "pushfl \n\t" "orl $0x100, (%%esp) \n\t" "popfl \n\t" "nop \n\t" "nop \n\t" "outb %b0, %w1 \n\t" "nop \n\t" "nop \n\t" "pushfl \n\t" "xorl $0x100, (%%esp) \n\t" "popfl \n\t" :: "a"(2), "Nd" (80) ); } And I ran the c program with gdb. (gdb) disas main Dump of assembler code for function main: 0x080483e4 <+0>: push %ebp 0x080483e5 <+1>: mov %esp,%ebp 0x080483e7 <+3>: mov $0x2,%eax 0x080483ec <+8>: pushf 0x080483ed <+9>: orl $0x100,(%esp) 0x080483f4 <+16>: popf 0x080483f5 <+17>: nop 0x080483f6 <+18>: nop => 0x080483f7 <+19>: out %al,$0x50 0x080483f9 <+21>: nop 0x080483fa <+22>: nop 0x080483fb <+23>: pushf 0x080483fc <+24>: xorl $0x100,(%esp) 0x08048403 <+31>: popf 0x08048404 <+32>: pop %ebp 0x08048405 <+33>: ret End of assembler dump. (gdb) nexti Program received signal SIGSEGV, Segmentation fault. 0x080483f7 in main () (gdb) You can see when the program counter points to the out instruction, and I used nexti command to do single step execution, and it ends up a segmentation fault. According to the kvm code, it seems that x86_emulate_insn() will be called, indeed I don't see any code in that function takes care of the out instruction. But why this only affect single step execution? I actually have some other program that includes some out instructions, and the program runs okay. -- You are receiving this mail because: You are watching the assignee of the bug. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
