Hi Paolo, On Tue, Nov 24, 2020 at 5:12 PM Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote: > > On 24/11/20 09:33, Bin Meng wrote: > > From: Bin Meng <bin.meng@xxxxxxxxxxxxx> > > > > This makes up the test case for the following QEMU patch: > > http://patchwork.ozlabs.org/project/qemu-devel/patch/1605261378-77971-1-git-send-email-bmeng.cn@xxxxxxxxx/ > > > > Note the test case only fails on an unpatched QEMU with "accel=tcg". > > > > Signed-off-by: Bin Meng <bin.meng@xxxxxxxxxxxxx> > > --- > > Sending this as RFC since I am new to kvm-unit-tests > > > > x86/emulator.c | 38 ++++++++++++++++++++++++++++++++++++++ > > 1 file changed, 38 insertions(+) > > > > diff --git a/x86/emulator.c b/x86/emulator.c > > index e46d97e..6100b6d 100644 > > --- a/x86/emulator.c > > +++ b/x86/emulator.c > > @@ -6,10 +6,14 @@ > > #include "processor.h" > > #include "vmalloc.h" > > #include "alloc_page.h" > > +#include "usermode.h" > > > > #define memset __builtin_memset > > #define TESTDEV_IO_PORT 0xe0 > > > > +#define MAGIC_NUM 0xdeadbeefdeadbeefUL > > +#define GS_BASE 0x400000 > > + > > static int exceptions; > > > > /* Forced emulation prefix, used to invoke the emulator unconditionally. */ > > @@ -925,6 +929,39 @@ static void test_sreg(volatile uint16_t *mem) > > write_ss(ss); > > } > > > > +static uint64_t usr_gs_mov(void) > > +{ > > + static uint64_t dummy = MAGIC_NUM; > > + uint64_t dummy_ptr = (uint64_t)&dummy; > > + uint64_t ret; > > + > > + dummy_ptr -= GS_BASE; > > + asm volatile("mov %%gs:(%%rcx), %%rax" : "=a"(ret): "c"(dummy_ptr) :); > > + > > + return ret; > > +} > > + > > +static void test_iret(void) > > +{ > > + uint64_t val; > > + bool raised_vector; > > + > > + /* Update GS base to 4MiB */ > > + wrmsr(MSR_GS_BASE, GS_BASE); > > + > > + /* > > + * Per the SDM, jumping to user mode via `iret`, which is returning to > > + * outer privilege level, for segment registers (ES, FS, GS, and DS) > > + * if the check fails, the segment selector becomes null. > > + * > > + * In our test case, GS becomes null. > > + */ > > + val = run_in_user((usermode_func)usr_gs_mov, GP_VECTOR, > > + 0, 0, 0, 0, &raised_vector); > > + > > + report(val == MAGIC_NUM, "Test ret/iret with a nullified segment"); > > +} > > + > > /* Broken emulation causes triple fault, which skips the other tests. */ > > #if 0 > > static void test_lldt(volatile uint16_t *mem) > > @@ -1074,6 +1111,7 @@ int main(void) > > test_shld_shrd(mem); > > //test_lgdt_lidt(mem); > > test_sreg(mem); > > + test_iret(); > > //test_lldt(mem); > > test_ltr(mem); > > test_cmov(mem); > > > > Thanks, the patch is good. Is this patch applied? Regards, Bin
