On Mon, 2023-09-18 at 11:21 +0000, Paul Durrant wrote:
>
> - ret = pthread_create(&thread, NULL, &juggle_shinfo_state, (void *)vm);
> + if (has_shinfo_hva)
> + ret = pthread_create(&thread, NULL,
> + &juggle_shinfo_state_hva, (void *)vm);
> + else
> + ret = pthread_create(&thread, NULL,
> + &juggle_shinfo_state_gfn, (void *)vm);
> TEST_ASSERT(ret == 0, "pthread_create() failed: %s", strerror(ret));
>
This means you don't exercise the GFN-based path (which all current VMM
implementations use) on newer kernels. Could you have a single
juggle_shinfo_state() function as before, but make it repeatedly set
and clear the shinfo using *both* HVA and GFN (if the former is
available, of course).
While you're at it, it looks like the thread leaves the shinfo
*deactivated*, which might come as a surprise to anyone who adds tests
at the end near the existing TEST_DONE. Can we make it leave the shinfo
*active* instead?
On 18/09/2023 14:19, David Woodhouse wrote:
> On Mon, 2023-09-18 at 11:21 +0000, Paul Durrant wrote:
>>
>> - ret = pthread_create(&thread, NULL, &juggle_shinfo_state, (void *)vm);
>> + if (has_shinfo_hva)
>> + ret = pthread_create(&thread, NULL,
>> + &juggle_shinfo_state_hva, (void *)vm);
>> + else
>> + ret = pthread_create(&thread, NULL,
>> + &juggle_shinfo_state_gfn, (void *)vm);
>> TEST_ASSERT(ret == 0, "pthread_create() failed: %s", strerror(ret));
>>
>
>
> This means you don't exercise the GFN-based path (which all current VMM
> implementations use) on newer kernels. Could you have a single
> juggle_shinfo_state() function as before, but make it repeatedly set
> and clear the shinfo using *both* HVA and GFN (if the former is
> available, of course).
The guidance is to use HVA if the feature is available; a VMM should not
really be mixing and matching. That said, setting it either way should
be equivalent.
>
> While you're at it, it looks like the thread leaves the shinfo
> *deactivated*, which might come as a surprise to anyone who adds tests
> at the end near the existing TEST_DONE. Can we make it leave the shinfo
> *active* instead?
Ok.
Paul
On Mon, 2023-09-18 at 14:24 +0100, Paul Durrant wrote:
> On 18/09/2023 14:19, David Woodhouse wrote:
> > On Mon, 2023-09-18 at 11:21 +0000, Paul Durrant wrote:
> > >
> > > - ret = pthread_create(&thread, NULL, &juggle_shinfo_state, (void *)vm);
> > > + if (has_shinfo_hva)
> > > + ret = pthread_create(&thread, NULL,
> > > + &juggle_shinfo_state_hva, (void *)vm);
> > > + else
> > > + ret = pthread_create(&thread, NULL,
> > > + &juggle_shinfo_state_gfn, (void *)vm);
> > > TEST_ASSERT(ret == 0, "pthread_create() failed: %s", strerror(ret));
> > >
> >
> >
> > This means you don't exercise the GFN-based path (which all current VMM
> > implementations use) on newer kernels. Could you have a single
> > juggle_shinfo_state() function as before, but make it repeatedly set
> > and clear the shinfo using *both* HVA and GFN (if the former is
> > available, of course).
>
> The guidance is to use HVA if the feature is available; a VMM should not
> really be mixing and matching. That said, setting it either way should
> be equivalent.
Sure, but this isn't really a VMM; it's a test harness to exercise a
bunch of ioctls. One of which it no longer bothers to test now, if the
new variant exists.
If we're going to keep the old API we should also continue to *test*
the old API. (And we should).