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 0FDA330676A; Fri, 19 Jun 2026 00:31:51 +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=1781829111; cv=none; b=nzX3qKIOsuXoqZQC8Td/C/cOymxaBJWRnJ9/hSDXZPAe+agldOrqe9kpZMw4DQ0XtUquwiOB4EzOSf58RFEYXhlH73zxR1V6TGR1MwkRIS+M8uBjbr+ybEl4M4Mtqp5af/a6ZgKCxQ84ckaW/A6jXxhMMxR1hV9K+8UETZnc1VU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781829111; c=relaxed/simple; bh=CelGdSIrcwF9eC8V3OzxEMp5LBaqPY/SgXdA3HXcPS8=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=d02d4z2tY0oj0aFvWZT651U8xUG4DZRdSdwm88Yn6ZJG65S47goHRvXQPG69GEIO4kDamfkY5UH7s7Vfaf4shO9/3alAWjffnNgm1FjjfGsxSwjxIlj3ftvIozb4/BxSGH4dewvC/3+ycayv+AEyLyCp/+S8uo+Rr0FQPPQi2JQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=rc5zH1uK; 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="rc5zH1uK" Received: by smtp.kernel.org (Postfix) with ESMTPS id D8C23C4AF09; Fri, 19 Jun 2026 00:31:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1781829110; bh=CelGdSIrcwF9eC8V3OzxEMp5LBaqPY/SgXdA3HXcPS8=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=rc5zH1uK/rn2RmSqmsgcgV9SoiEcQ2sC8AI8hE8KQDnbJWB/1ahCK1Z8hGZTsxlNb AwL/RJTrJbhsknNF3+irVVff/z/nkNRbdC4qnloLophp2hewBidksyOG7IPEdJ43uB ichlQJFOlN/TdBRlBgnkEIBsOZggkitQ/TOXuwJZ/wQHzgf/MMM7r89gtfZIktxjbb EoVOHUIq7l8fetILDvjklwd6GwlySBD6zNZDIbFZRnL+K3q+okcX4z1KuWLBWw/8Q5 v0D9M1fGcPvJn4iCjn48sTjgfpz2luI75NGnnGMOJt/yn1A9QFtwV2KiSR+8HMrBNG wmximvvbU+KSg== 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 C5898CDB464; Fri, 19 Jun 2026 00:31:50 +0000 (UTC) From: Ackerley Tng via B4 Relay Date: Thu, 18 Jun 2026 17:32:16 -0700 Subject: [PATCH v8 39/46] KVM: selftests: Test conversion with elevated page refcount Precedence: bulk X-Mailing-List: linux-kernel@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: <20260618-gmem-inplace-conversion-v8-39-9d2959357853@google.com> References: <20260618-gmem-inplace-conversion-v8-0-9d2959357853@google.com> In-Reply-To: <20260618-gmem-inplace-conversion-v8-0-9d2959357853@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, tabba@google.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 , 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=1781829104; l=3041; i=ackerleytng@google.com; s=20260225; h=from:subject:message-id; bh=RcEpvRGUyrZ9oNGCavid+DRt+Nqf2g3joo3oK0JU+QI=; b=1WdvTXOXFGcn5XmhM4B4XGBW7iYWn2QcIPuPJK0o7bdLfsq5Wl0T7yXsUwYOTD+Wa49SefCno Ipl+1eP+/o5CHbj6wvDYl5+H8w8x8p9faLnFJC67HSVIHhlPSA+0T6o 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. Signed-off-by: Ackerley Tng Co-developed-by: Sean Christopherson Signed-off-by: Sean Christopherson --- .../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 99b0023609670..4ebbd29029526 100644 --- a/tools/testing/selftests/kvm/x86/guest_memfd_conversions_test.c +++ b/tools/testing/selftests/kvm/x86/guest_memfd_conversions_test.c @@ -441,6 +441,62 @@ 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.rc0.738.g0c8ab3ebcc-goog