linux-kernel - [RFC PATCH v1 22/37] KVM: selftests: guest_memfd: Test conversion before allocation

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Message-ID: <ab6491c3eac047b8c0fd4cbfcb021e6327124203.1760731772.git.ackerleytng@google.com>
Date: Fri, 17 Oct 2025 13:12:03 -0700
From: Ackerley Tng <ackerleytng@...gle.com>
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Subject: [RFC PATCH v1 22/37] KVM: selftests: guest_memfd: Test conversion
 before allocation

Add two test cases to the guest_memfd conversions selftest to cover
the scenario where a conversion is requested before any memory has been
allocated in the guest_memfd region.

The KVM_MEMORY_CONVERT_GUEST ioctl can be called on a memory region at any
time. If the guest has not yet faulted in any pages for that region, the
kernel must record the conversion request and apply the requested state
when the pages are eventually allocated.

The new tests cover both conversion directions.

Signed-off-by: Ackerley Tng <ackerleytng@...gle.com>
Co-developed-by: Sean Christopherson <seanjc@...gle.com>
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 .../selftests/kvm/guest_memfd_conversions_test.c   | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/tools/testing/selftests/kvm/guest_memfd_conversions_test.c b/tools/testing/selftests/kvm/guest_memfd_conversions_test.c
index 54e7deec992d4..3b222009227c3 100644
--- a/tools/testing/selftests/kvm/guest_memfd_conversions_test.c
+++ b/tools/testing/selftests/kvm/guest_memfd_conversions_test.c
@@ -263,6 +263,20 @@ GMEM_CONVERSION_MULTIPAGE_TEST_INIT_SHARED(indexing, 4)
 	}
 }
 
+/*
+ * Test that even if there are no folios yet, conversion requests are recorded
+ * in guest_memfd.
+ */
+GMEM_CONVERSION_TEST_INIT_SHARED(before_allocation_shared)
+{
+	test_convert_to_private(t, 0, 0, 'A');
+}
+
+GMEM_CONVERSION_TEST_INIT_PRIVATE(before_allocation_private)
+{
+	test_convert_to_shared(t, 0, 0, 'A', 'B');
+}
+
 int main(int argc, char *argv[])
 {
 	TEST_REQUIRE(kvm_check_cap(KVM_CAP_VM_TYPES) & BIT(KVM_X86_SW_PROTECTED_VM));
-- 
2.51.0.858.gf9c4a03a3a-goog