From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 936363CF209; Thu, 10 Sep 2026 23:55:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789084540; cv=none; b=rdox9LW2Nb6KD+NzJn/in8WO1fxqYG0hEUQBzVpNEJfQ8g9hBQf50Qj6fig42JtvWd09xpKfORGRmQ0CC/BW0qiv6tvDpNiPwvgUVYFSzFEKH+GXPly5Onb0U+OACfFBR3iOr+aSl91e67AzJXtzV1TS3OW4RUfogGqPmyFsRLc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789084540; c=relaxed/simple; bh=G8N4ShrkYGN5GBTB755cDv3HxqeV741x6ACmQkhLBp0=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=A87yexO274Y6W1XzWoRwnM0jDn8e2OxHwasd3szFa6ZsKKk3chxbLnBx8S+60RDqt46e+QAnrhEfPhPpyLo5hFjnYeI8j0Ro6xiRCQwKr0cwHBVOIGWqkIbO52PeR+3BgMA59oY2b46cFUtCQJl+6855eLZ9LrfsBb/Vaksv4Pg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=qY2F3Brc; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="qY2F3Brc" Received: by smtp.kernel.org (Postfix) with ESMTPS id 70C12C4AF1A; Thu, 10 Sep 2026 23:55:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1789084540; bh=G8N4ShrkYGN5GBTB755cDv3HxqeV741x6ACmQkhLBp0=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=qY2F3BrcEAlD9+DUuhU1Ag9LdFgkB1u4J6mSq8WG5HY6wxdUHaxQe7dsCkH7dywU0 EwNmPAnTZ9np7xSpJsD/KSG9pCC7Vy9tVnG+8OWlnrwaUBgsTNJt7wUxuSruG4UTFg F7zvhRo2eSq+Pqk5IQWIZEP07bynY7se3WMJgUP0ujPWLGS4JADL6haeS06bzxQ4aI jyjE2B13z/hMIYrvNYpGO0/mlrRfP7bkY7nGvrr/6P57VZf2cEkuaLwwZ54kVjWtF6 7J5Twe7/XRRruvQaAVlgTSKHLp1QTw80MAVwSe2vj2QF9JLVxmr0DMRuX5RMso0pA0 R8U0M7gcHqZQw== Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5AACBC88E4D; Thu, 10 Sep 2026 23:55:40 +0000 (UTC) From: Ackerley Tng via B4 Relay Date: Thu, 10 Sep 2026 16:56:03 -0700 Subject: [PATCH v13 37/44] KVM: selftests: Test conversion with elevated page refcount Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260910-gmem-inplace-conversion-v13-37-dd6fbf94f4e1@google.com> References: <20260910-gmem-inplace-conversion-v13-0-dd6fbf94f4e1@google.com> In-Reply-To: <20260910-gmem-inplace-conversion-v13-0-dd6fbf94f4e1@google.com> To: aik@amd.com, andrew.jones@linux.dev, binbin.wu@linux.intel.com, brauner@kernel.org, chao.p.peng@linux.intel.com, david@kernel.org, jmattson@google.com, jthoughton@google.com, michael.roth@amd.com, oupton@kernel.org, pankaj.gupta@amd.com, qperret@google.com, rick.p.edgecombe@intel.com, rientjes@google.com, shivankg@amd.com, steven.price@arm.com, willy@infradead.org, wyihan@google.com, yan.y.zhao@intel.com, forkloop@google.com, pratyush@kernel.org, suzuki.poulose@arm.com, aneesh.kumar@kernel.org, liam@infradead.org, Paolo Bonzini , Sean Christopherson , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Jonathan Corbet , Shuah Khan , Shuah Khan , Vishal Annapurve , Andrew Morton , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Youngjun Park , Qi Zheng , Shakeel Butt , Kiryl Shutsemau , Baoquan He , Jason Gunthorpe , John Hubbard , Peter Xu , tarunsahu@google.com, Randy Dunlap , Lorenzo Stoakes , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jason Gunthorpe , Fuad Tabba , Vlastimil Babka , Baoquan He Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, linux-coco@lists.linux.dev, Ackerley Tng X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=ed25519-sha256; t=1789084533; l=3126; i=ackerleytng@google.com; s=20260225; h=from:subject:message-id; bh=PmSTG3Mn3VeRBRB+Sk4c+WCKivO001+yahByLRYiXQc=; b=RpykbcULhzk4ajqe3DS/wC8n7+NFwOF0ACIKr+g2KTH4KaYSGPwwQkK/DSqTHRM2PdjRrrgAu Q3Hqr1m2V5LBan2oI5vKX8wYPbB8YSk5b4E/+D8Y4Rnch7JyaXKpDli X-Developer-Key: i=ackerleytng@google.com; a=ed25519; pk=sAZDYXdm6Iz8FHitpHeFlCMXwabodTm7p8/3/8xUxuU= X-Endpoint-Received: by B4 Relay for ackerleytng@google.com/20260225 with auth_id=649 X-Original-From: Ackerley Tng Reply-To: ackerleytng@google.com From: Ackerley Tng Add a selftest to verify that converting a shared guest_memfd page to a private page fails if the page has an elevated reference count. When KVM converts a shared page to a private one, it expects the page to have a reference count equal to the reference counts taken by the filemap. If another kernel subsystem holds a reference to the page, the conversion must be aborted. The test asserts that both bulk and single-page conversion attempts correctly fail with EAGAIN for the pinned page. After the page is unpinned, the test verifies that subsequent conversions succeed. Co-developed-by: Sean Christopherson Signed-off-by: Sean Christopherson Signed-off-by: Ackerley Tng Tested-by: Shivank Garg Reviewed-by: Fuad Tabba --- .../kvm/x86/guest_memfd_conversions_test.c | 56 ++++++++++++++++++++++ 1 file changed, 56 insertions(+) diff --git a/tools/testing/selftests/kvm/x86/guest_memfd_conversions_test.c b/tools/testing/selftests/kvm/x86/guest_memfd_conversions_test.c index a972a09c5c6e5..e1c84df0f0596 100644 --- a/tools/testing/selftests/kvm/x86/guest_memfd_conversions_test.c +++ b/tools/testing/selftests/kvm/x86/guest_memfd_conversions_test.c @@ -444,6 +444,62 @@ GMEM_CONVERSION_TEST_INIT_SHARED(forked_accesses) #undef TEST_STATE_AWAIT } +static void test_convert_to_private_fails(test_data_t *t, u64 pgoff, + size_t nr_pages, + u64 expected_error_offset) +{ + /* +1 to make it anything but expected_error_offset. */ + u64 error_offset = expected_error_offset + 1; + u64 offset = pgoff * page_size; + int ret; + + do { + ret = __gmem_set_private(t->gmem_fd, offset, + nr_pages * page_size, &error_offset); + } while (ret == -1 && errno == EINTR); + TEST_ASSERT(ret == -1 && errno == EAGAIN, + "Wanted EAGAIN on page %lu, got %d (ret = %d)", pgoff, + errno, ret); + TEST_ASSERT_EQ(error_offset, expected_error_offset); +} + +GMEM_CONVERSION_MULTIPAGE_TEST_INIT_SHARED(elevated_refcount, 4) +{ + int i; + + pin_pages(t->mem + test_page * page_size, page_size); + + for (i = 0; i < nr_pages; i++) + test_shared(t, i, 0, 'A', 'B'); + + /* + * Converting in bulk should fail as long any page in the range has + * unexpected refcounts. + */ + test_convert_to_private_fails(t, 0, nr_pages, test_page * page_size); + + for (i = 0; i < nr_pages; i++) { + /* + * Converting page-wise should also fail as long any page in the + * range has unexpected refcounts. + */ + if (i == test_page) + test_convert_to_private_fails(t, i, 1, test_page * page_size); + else + test_convert_to_private(t, i, 'B', 'C'); + } + + unpin_pages(); + + gmem_set_private(t->gmem_fd, 0, nr_pages * page_size); + + for (i = 0; i < nr_pages; i++) { + char expected = i == test_page ? 'B' : 'C'; + + test_private(t, i, expected, 'D'); + } +} + int main(int argc, char *argv[]) { TEST_REQUIRE(kvm_check_cap(KVM_CAP_VM_TYPES) & BIT(KVM_X86_SW_PROTECTED_VM)); -- 2.55.0.1007.g17ff1f9808-goog