On Fri, Apr 09, 2021, Paolo Bonzini wrote:
> On 09/04/21 09:55, Yang Weijiang wrote:
> > During kvm-unit-test, below failure pattern is observed, this is due to testing thread
> > migration + cache "lazy" flush during test, so forcely flush the cache to avoid the issue.
> > Pin the test app to certain physical CPU can fix the issue as well. The error report is
> > misleading, pke is the victim of the issue.
> >
> > test user cr4.pke: FAIL: error code 5 expected 4
> > Dump mapping: address: 0x123400000000
> > ------L4: 21ea007
> > ------L3: 21eb007
> > ------L2: 21ec000
> > ------L1: 2000000
> >
> > Signed-off-by: Yang Weijiang <weijiang.yang@xxxxxxxxx>
> > ---
> > x86/access.c | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> > diff --git a/x86/access.c b/x86/access.c
> > index 7dc9eb6..379d533 100644
> > --- a/x86/access.c
> > +++ b/x86/access.c
> > @@ -211,6 +211,8 @@ static unsigned set_cr4_smep(int smep)
> > ptl2[2] |= PT_USER_MASK;
> > if (!r)
> > shadow_cr4 = cr4;
> > +
> > + invlpg((void *)(ptl2[2] & ~PAGE_SIZE));
> > return r;
> > }
> >
>
> Applied, thanks.
Egad, I can't keep up with this new Paolo :-D
Would it also work to move the existing invlpg() into ac_test_do_access()?
diff --git a/x86/access.c b/x86/access.c
index 7dc9eb6..5f335dd 100644
--- a/x86/access.c
+++ b/x86/access.c
@@ -451,8 +451,6 @@ fault:
static void ac_set_expected_status(ac_test_t *at)
{
- invlpg(at->virt);
-
if (at->ptep)
at->expected_pte = *at->ptep;
at->expected_pde = *at->pdep;
@@ -658,6 +656,9 @@ static int ac_test_do_access(ac_test_t *at)
set_cr4_smep(F(AC_CPU_CR4_SMEP));
+ /* Flush after _all_ setup is done, toggling SMEP may also modify PMDs. */
+ invlpg(at->virt);
+
if (F(AC_ACCESS_TWICE)) {
asm volatile (
"mov $fixed2, %%rsi \n\t
