Yes, I load kvm-intel with unrestricted_guest=0 and the emulator runs
well. I will give another test case in x86/realmode.c later.
BTW, what is the action when a 64-bit instruction executes in
x86/realmode.c? Should I add 64-bit insn tests only in x86/emulator.c?
On Wed, Jun 5, 2013 at 4:27 PM, Gleb Natapov <gleb@xxxxxxxxxx> wrote:
> On Wed, Jun 05, 2013 at 03:00:33PM +0800, 李春奇 <Arthur Chunqi Li> wrote:
>> Yes, that should be the point. x86/realmode.c is always running in
>> emulation mode. I added the testing here there but no error occurred. I
>> cannot find the reason.
>>
>> The code is as follows added to x86/realmode.c
>> static void test_nopl(void)
>> {
>> MK_INSN(nopl, ".byte 0x0f, 0x1f, 0x00\n\r");
>> exec_in_big_real_mode(&insn_nopl);
>> report("nopl", 0, 1);
>> }
>>
>> and I objdump from realmode.flat is as follows:
>> 00006458 <insn_code_nopl>:
>> 6458: 0f 1f 00 nopl (%eax)
>>
>> But there cause no error when executing this insn. Why?
>>
> Because you probably use cpu that supports unrestricted mode or use AMD
> processor. Can you try loading kvm-intel with unrestricted_guest=0
> option?
>
>>
>> On Wed, Jun 5, 2013 at 2:42 PM, Gleb Natapov <gleb@xxxxxxxxxx> wrote:
>>
>> > On Wed, Jun 05, 2013 at 10:16:46AM +0800, 李春奇 <Arthur Chunqi Li> wrote:
>> > > Add multibyte NOP test case to kvm-unit-tests. This case can test one
>> > > of bugs when booting RHEL5.9 64-bit.
>> > >
>> > Adding the test to x86/realmode.c will be much easier.
>> >
>> > > Signed-off-by: Arthur Chunqi Li <yzt356@xxxxxxxxx>
>> > > ---
>> > > x86/emulator.c | 33 +++++++++++++++++++++++++++++++++
>> > > 1 file changed, 33 insertions(+)
>> > >
>> > > diff --git a/x86/emulator.c b/x86/emulator.c
>> > > index 96576e5..f26c70f 100644
>> > > --- a/x86/emulator.c
>> > > +++ b/x86/emulator.c
>> > > @@ -901,6 +901,37 @@ static void test_simplealu(u32 *mem)
>> > > report("test", *mem == 0x8400);
>> > > }
>> > >
>> > > +static void test_nopl(uint64_t *mem, uint8_t *insn_page,
>> > > + uint8_t *alt_insn_page, void *insn_ram)
>> > > +{
>> > > + ulong *cr3 = (ulong *)read_cr3();
>> > > +
>> > > + // Pad with RET instructions
>> > > + memset(insn_page, 0xc3, 4096);
>> > > + memset(alt_insn_page, 0xc3, 4096);
>> > > + // Place a trapping instruction in the page to trigger a VMEXIT
>> > > + insn_page[0] = 0x89; // mov %eax, (%rax)
>> > > + insn_page[1] = 0x00;
>> > > + insn_page[2] = 0x90; // nop
>> > > + // Place nopl 0x0(%eax) in alt_insn_page for emulator to execuate
>> > > + alt_insn_page[0] = 0x0f; // nop DWORD ptr[EAX]
>> > > + alt_insn_page[1] = 0x1f;
>> > > + alt_insn_page[2] = 0x00;
>> > > +
>> > > + // Load the code TLB with insn_page, but point the page tables at
>> > > + // alt_insn_page (and keep the data TLB clear, for AMD decode
>> > assist).
>> > > + // This will make the CPU trap on the insn_page instruction but the
>> > > + // hypervisor will see alt_insn_page.
>> > > + install_page(cr3, virt_to_phys(insn_page), insn_ram);
>> > > + // Load code TLB
>> > > + invlpg(insn_ram);
>> > > + asm volatile("call *%0" : : "r"(insn_ram + 3));
>> > > + // Trap, let hypervisor emulate at alt_insn_page
>> > > + install_page(cr3, virt_to_phys(alt_insn_page), insn_ram);
>> > > + asm volatile("call *%0" : : "r"(insn_ram), "a"(mem));
>> > > + report("nopl", 1);
>> > > +}
>> > > +
>> > > int main()
>> > > {
>> > > void *mem;
>> > > @@ -964,6 +995,8 @@ int main()
>> > >
>> > > test_string_io_mmio(mem);
>> > >
>> > > + test_nopl(mem, insn_page, alt_insn_page, insn_ram);
>> > > +
>> > > printf("\nSUMMARY: %d tests, %d failures\n", tests, fails);
>> > > return fails ? 1 : 0;
>> > > }
>> > > --
>> > > 1.7.9.5
>> >
>> > --
>> > Gleb.
>> >
>>
>>
>>
>> --
>> Arthur Chunqi Li
>> Department of Computer Science
>> School of EECS
>> Peking University
>> Beijing, China
>
> --
> Gleb.
--
Arthur Chunqi Li
Department of Computer Science
School of EECS
Peking University
Beijing, China
--
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
