Re: [PATCH 2/2] KVM: arm64: selftests: test for vgic redist above the VM IPA size

[Ricardo Koller <ricarkol@google.com>]

On Thu, Sep 09, 2021 at 03:54:31PM +0200, Eric Auger wrote:
> Hi Ricardo,
> 
> On 9/8/21 11:03 PM, Ricardo Koller wrote:
> > This test attempts (and fails) to set a redistributor region using the
> > legacy KVM_VGIC_V3_ADDR_TYPE_REDIST that's partially above the
> > VM-specified IPA size.
> >
> > Signed-off-by: Ricardo Koller <ricarkol@google.com>
> > ---
> >  .../testing/selftests/kvm/aarch64/vgic_init.c | 44 +++++++++++++++++++
> >  1 file changed, 44 insertions(+)
> >
> > diff --git a/tools/testing/selftests/kvm/aarch64/vgic_init.c b/tools/testing/selftests/kvm/aarch64/vgic_init.c
> > index 623f31a14326..6dd7b5e91421 100644
> > --- a/tools/testing/selftests/kvm/aarch64/vgic_init.c
> > +++ b/tools/testing/selftests/kvm/aarch64/vgic_init.c
> > @@ -285,6 +285,49 @@ static void test_vcpus_then_vgic(void)
> >  	vm_gic_destroy(&v);
> >  }
> >  
> > +static void test_redist_above_vm_pa_bits(enum vm_guest_mode mode)
> > +{
> > +	struct vm_gic v;
> > +	int ret, i;
> > +	uint32_t vcpuids[] = { 1, 2, 3, 4, };
> > +	int pa_bits = vm_guest_mode_params[mode].pa_bits;
> > +	uint64_t addr, psize = 1ULL << pa_bits;
> > +
> > +	/* Add vcpu 1 */
> > +	v.vm = vm_create_with_vcpus(mode, 1, DEFAULT_GUEST_PHY_PAGES,
> > +				    0, 0, guest_code, vcpuids);
> > +	v.gic_fd = kvm_create_device(v.vm, KVM_DEV_TYPE_ARM_VGIC_V3, false);
> > +
> > +	/* Set space for half a redist, we have 1 vcpu, so this fails. */
> > +	addr = psize - 0x10000;
> > +	ret = _kvm_device_access(v.gic_fd, KVM_DEV_ARM_VGIC_GRP_ADDR,
> > +				 KVM_VGIC_V3_ADDR_TYPE_REDIST, &addr, true);
> > +	TEST_ASSERT(ret && errno == EINVAL, "not enough space for one redist");
> > +
> > +	/* Set space for 3 redists, we have 1 vcpu, so this succeeds. */
> > +	addr = psize - (3 * 2 * 0x10000);
> > +	kvm_device_access(v.gic_fd, KVM_DEV_ARM_VGIC_GRP_ADDR,
> > +				 KVM_VGIC_V3_ADDR_TYPE_REDIST, &addr, true);
> 
> I think you need to test both the old API (KVM_VGIC_V3_ADDR_TYPE_REDIST)
> and the new one (KVM_VGIC_V3_ADDR_TYPE_REDIST_REGION).
> 
> Can't you integrate those new checks in existing tests,
> subtest_redist_regions() and subtest_dist_rdist() which already tests
> base addr beyond IPA limit (but not range end unfortunately). look for
> E2BIG.
> 

Had some issues adapting subtest_dist_rdist() as the IPA range check for
ADDR_TYPE_REDIST is done at 1st vcpu run.  subtest_dist_rdist() is
already used to set overlapping dist/redist regions, which is then
checked to generate EINVAL on 1st vcpu run. If subtest_dist_rdist() is
also used to set the redist region above phys_size, then there won't be
a way of checking that the vcpu run fails because of both the overlap
and IPA issue.  It was simpler and cleaner to just add a new function
for the ADDR_TYPE_REDIST IPA range test.  Will adapt
subtest_redist_regions() as the check for ADDR_TYPE_REDIST_REGION can be
done when setting the regions.

Related Question:

Both the KVM_VGIC_V3_ADDR_TYPE_REDIST and KVM_RUN currently return
EINVAL with my proposed change (not E2BIG). I will change
KVM_VGIC_V3_ADDR_TYPE_REDIST to fail with E2BIG, but will leave KVM_RUN
failing with EINVAL.  Would you say that's the correct behavior?

Thanks,
Ricardo

> Thanks
> 
> Eric
> > +
> > +	addr = 0x00000;
> > +	kvm_device_access(v.gic_fd, KVM_DEV_ARM_VGIC_GRP_ADDR,
> > +			KVM_VGIC_V3_ADDR_TYPE_DIST, &addr, true);
> > +
> > +	/* Add three vcpus (2, 3, 4). */
> > +	for (i = 1; i < 4; ++i)
> > +		vm_vcpu_add_default(v.vm, vcpuids[i], guest_code);
> > +
> > +	kvm_device_access(v.gic_fd, KVM_DEV_ARM_VGIC_GRP_CTRL,
> > +			  KVM_DEV_ARM_VGIC_CTRL_INIT, NULL, true);
> > +
> > +	/* Attempt to run a vcpu without enough redist space. */
> > +	ret = run_vcpu(v.vm, vcpuids[3]);
> > +	TEST_ASSERT(ret && errno == EINVAL,
> > +			"redist base+size above IPA detected on 1st vcpu run");
> > +
> > +	vm_gic_destroy(&v);
> > +}
> > +
> >  static void test_new_redist_regions(void)
> >  {
> >  	void *dummy = NULL;
> > @@ -542,6 +585,7 @@ int main(int ac, char **av)
> >  	test_kvm_device();
> >  	test_vcpus_then_vgic();
> >  	test_vgic_then_vcpus();
> > +	test_redist_above_vm_pa_bits(VM_MODE_DEFAULT);
> >  	test_new_redist_regions();
> >  	test_typer_accesses();
> >  	test_last_bit_redist_regions();
>