* [kvm-unit-tests][RFC PATCH] x86: Add a new test case for ret/iret with a nullified segment
@ 2020-11-24 8:33 Bin Meng
2020-11-24 9:12 ` Paolo Bonzini
0 siblings, 1 reply; 4+ messages in thread
From: Bin Meng @ 2020-11-24 8:33 UTC (permalink / raw)
To: Paolo Bonzini, kvm; +Cc: Bin Meng
From: Bin Meng <bin.meng@windriver.com>
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@gmail.com/
Note the test case only fails on an unpatched QEMU with "accel=tcg".
Signed-off-by: Bin Meng <bin.meng@windriver.com>
---
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);
--
2.7.4
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [kvm-unit-tests][RFC PATCH] x86: Add a new test case for ret/iret with a nullified segment
2020-11-24 8:33 [kvm-unit-tests][RFC PATCH] x86: Add a new test case for ret/iret with a nullified segment Bin Meng
@ 2020-11-24 9:12 ` Paolo Bonzini
2021-01-16 14:16 ` Bin Meng
0 siblings, 1 reply; 4+ messages in thread
From: Paolo Bonzini @ 2020-11-24 9:12 UTC (permalink / raw)
To: Bin Meng, kvm; +Cc: Bin Meng
On 24/11/20 09:33, Bin Meng wrote:
> From: Bin Meng <bin.meng@windriver.com>
>
> 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@gmail.com/
>
> Note the test case only fails on an unpatched QEMU with "accel=tcg".
>
> Signed-off-by: Bin Meng <bin.meng@windriver.com>
> ---
> 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.
Paolo
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [kvm-unit-tests][RFC PATCH] x86: Add a new test case for ret/iret with a nullified segment
2020-11-24 9:12 ` Paolo Bonzini
@ 2021-01-16 14:16 ` Bin Meng
2021-01-18 17:54 ` Paolo Bonzini
0 siblings, 1 reply; 4+ messages in thread
From: Bin Meng @ 2021-01-16 14:16 UTC (permalink / raw)
To: Paolo Bonzini; +Cc: kvm, Bin Meng
Hi Paolo,
On Tue, Nov 24, 2020 at 5:12 PM Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> On 24/11/20 09:33, Bin Meng wrote:
> > From: Bin Meng <bin.meng@windriver.com>
> >
> > 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@gmail.com/
> >
> > Note the test case only fails on an unpatched QEMU with "accel=tcg".
> >
> > Signed-off-by: Bin Meng <bin.meng@windriver.com>
> > ---
> > 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
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [kvm-unit-tests][RFC PATCH] x86: Add a new test case for ret/iret with a nullified segment
2021-01-16 14:16 ` Bin Meng
@ 2021-01-18 17:54 ` Paolo Bonzini
0 siblings, 0 replies; 4+ messages in thread
From: Paolo Bonzini @ 2021-01-18 17:54 UTC (permalink / raw)
To: Bin Meng; +Cc: kvm, Bin Meng
On 16/01/21 15:16, Bin Meng wrote:
> Hi Paolo,
>
> On Tue, Nov 24, 2020 at 5:12 PM Paolo Bonzini <pbonzini@redhat.com> wrote:
>>
>> On 24/11/20 09:33, Bin Meng wrote:
>>> From: Bin Meng <bin.meng@windriver.com>
>>>
>>> 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@gmail.com/
>>>
>>> Note the test case only fails on an unpatched QEMU with "accel=tcg".
>>>
>>> Signed-off-by: Bin Meng <bin.meng@windriver.com>
>>> ---
>>> 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
>
Yes, it is.
Paolo
^ permalink raw reply [flat|nested] 4+ messages in thread
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2020-11-24 8:33 [kvm-unit-tests][RFC PATCH] x86: Add a new test case for ret/iret with a nullified segment Bin Meng
2020-11-24 9:12 ` Paolo Bonzini
2021-01-16 14:16 ` Bin Meng
2021-01-18 17:54 ` Paolo Bonzini
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