[PATCH] KVM: selftests: Ignore KVM 5-level paging support for VM_MODE_PXXV48_4K

From: Sean Christopherson
Date: Wed May 27 2020 - 22:15:34 EST


Explicitly set the VA width to 48 bits for the x86_64-only PXXV48_4K VM
mode instead of asserting the guest VA width is 48 bits. The fact that
KVM supports 5-level paging is irrelevant unless the selftests opt-in to
5-level paging by setting CR4.LA57 for the guest. The overzealous
assert prevents running the selftests on a kernel with 5-level paging
enabled.

Incorporate LA57 into the assert instead of removing the assert entirely
as a sanity check of KVM's CPUID output.

Fixes: 567a9f1e9deb ("KVM: selftests: Introduce VM_MODE_PXXV48_4K")
Reported-by: Sergio Perez Gonzalez <sergio.perez.gonzalez@xxxxxxxxx>
Cc: Adriana Cervantes Jimenez <adriana.cervantes.jimenez@xxxxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
---
tools/testing/selftests/kvm/lib/kvm_util.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index c9cede5c7d0de..74776ee228f2d 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -195,11 +195,18 @@ struct kvm_vm *_vm_create(enum vm_guest_mode mode, uint64_t phy_pages, int perm)
case VM_MODE_PXXV48_4K:
#ifdef __x86_64__
kvm_get_cpu_address_width(&vm->pa_bits, &vm->va_bits);
- TEST_ASSERT(vm->va_bits == 48, "Linear address width "
- "(%d bits) not supported", vm->va_bits);
+ /*
+ * Ignore KVM support for 5-level paging (vm->va_bits == 57),
+ * it doesn't take effect unless a CR4.LA57 is set, which it
+ * isn't for this VM_MODE.
+ */
+ TEST_ASSERT(vm->va_bits == 48 || vm->va_bits == 57,
+ "Linear address width (%d bits) not supported",
+ vm->va_bits);
pr_debug("Guest physical address width detected: %d\n",
vm->pa_bits);
vm->pgtable_levels = 4;
+ vm->va_bits = 48;
#else
TEST_FAIL("VM_MODE_PXXV48_4K not supported on non-x86 platforms");
#endif
--
2.26.0