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X-CSE-ConnectionGUID: gWEm5T10RbOpoaUcKZ+OdA== X-CSE-MsgGUID: 5ZFTQxrDS2mNSIyxHA/RoQ== X-IronPort-AV: E=McAfee;i="6800,10657,11885"; a="91797078" X-IronPort-AV: E=Sophos;i="6.25,242,1779174000"; d="scan'208";a="91797078" Received: from orviesa008.jf.intel.com ([10.64.159.148]) by orvoesa107.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Aug 2026 03:06:42 -0700 X-CSE-ConnectionGUID: T+xKrRR4SkK84ruPBSE65Q== X-CSE-MsgGUID: shDtClh4RZWx8bZXjoSkTw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.25,242,1779174000"; d="scan'208";a="266698413" Received: from xiaoyaol-hp-g830.ccr.corp.intel.com (HELO [10.124.240.119]) ([10.124.240.119]) by orviesa008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Aug 2026 03:06:28 -0700 Message-ID: <9feadfea-c41c-4105-963a-a3d98421e1c3@intel.com> Date: Tue, 25 Aug 2026 18:06:25 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v10 40/41] KVM: selftests: Update private_mem_conversions_test to mmap() guest_memfd To: Ackerley Tng , Sean Christopherson Cc: 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 , 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, Vlastimil Babka , 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 References: <20260807-gmem-inplace-conversion-v10-0-2fc18ee6d3ba@google.com> <20260807-gmem-inplace-conversion-v10-40-2fc18ee6d3ba@google.com> Content-Language: en-US From: Xiaoyao Li In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Queue-Id: A435840003 X-Rspamd-Server: rspam07 X-Stat-Signature: 6f8miebh4m4a4r4am61w494674517p38 X-HE-Tag: 1787652402-695375 X-HE-Meta: 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 gExTRiKt N1+8U7ld+fSKjHejgWgiETcPT7V7l2TWuXq2oKVoaJ5z7uc3feqZNr/G+tDgefeXIp21bFD175dXHDvLapMyWju+uEu7fcQs/2SK3bj21Y0GN5vGgPOyJJdt9T9t41n8PR3bQwUkQgN5b4hCkvCvDZCja35759UlbIpDKcZdOUb7DDDyeJrabdhWWlsSUB6hSfmaj07zus2zxaeVinXaa5Nf1YPKzzSifdansdqVJrzYAYysC7HmaaAbO1QDCPV7nxCIL0W3fU4p6Sr/BwSgnQcdD0Q== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 8/25/2026 5:32 PM, Ackerley Tng wrote: > Sean Christopherson writes: > >> On Fri, Aug 21, 2026, Xiaoyao Li wrote: >>> On 8/8/2026 5:53 AM, Ackerley Tng via B4 Relay wrote: >>>> From: Ackerley Tng >>>> >>>> Update the private memory conversions selftest to also test conversions >>>> that are done "in-place" via per-guest_memfd memory attributes. In-place >>>> conversions require the host to be able to mmap() the guest_memfd so that >>>> the host and guest can share the same backing physical memory. >>>> >>>> This includes several updates, that are conditioned on the system >>>> supporting per-guest_memfd attributes (kvm_has_gmem_attributes): >>>> >>>> 1. Set up guest_memfd requesting MMAP and INIT_SHARED. >>> >>> If I understand correctly, even with in-place gmem, the model that shared >>> memory comes from the userspace_addr and private memory comes from gmem can >>> still work without passing GUEST_MEMFD_FLAG_MMAP flag. >>> >>> Since this model is not prohibited by KVM. I think we should keep the >>> testcase for this model to ensure test coverage? >> >> +1. Deprecated doesn't mean unsupported. > > The original test case was for non-in-place conversion, which wasn't > removed, it still passes. It only passes when /sys/module/kvm/parameters/gmem_in_place_conversion=n It fails as below when gmem_in_place_conversion=y ./tools/testing/selftests/kvm/x86/private_mem_conversions_test Random seed: 0x7eace343 ==== Test Assertion Failure ==== x86/private_mem_conversions_test.c:46: mem[i] == pattern pid=288745 tid=288747 errno=4 - Interrupted system call 1 0x000000000040426a: memcmp_h at private_mem_conversions_test.c:46 2 (inlined by) __test_mem_conversions at private_mem_conversions_test.c:356 3 0x00007f2ea2c89c01: ?? ??:0 4 0x00007f2ea2d0ec3f: ?? ??:0 Host expected 0xaa at gpa 0x100000000, got 0x0 > Is the ask to also test, under kvm_has_gmem_attributes aka > gmem_in_place_conversion, to have guest_memfd used as purely for private > memory and have shared memory taken from somewhere else completely? > > I can rephrase the changelog and change the code to clarify that this > patch is meant to specifically test in-place conversion with MMAP, the > intended usage of in-place conversions. > > The ask to test gmem for private and something else for shared seems > like a different test that can be added separately, perhaps in a > follow-up series? I see it as the fix for existing testcase, not another new test. And the fix is simple: 1. change to use vm_mem_set_memory_attributes() to set memory attribute. 2. pass GUEST_MEMFD_FLAG_INIT_SHARED to create the gmem because this test expects the initial state of the gfn is shared. ---8<---- diff --git a/tools/testing/selftests/kvm/x86/private_mem_conversions_test.c b/tools/testing/selftests/kvm/x86/private_mem_conversions_test.c index cf50e9a332c5..fbd6c63d21cf 100644 --- a/tools/testing/selftests/kvm/x86/private_mem_conversions_test.c +++ b/tools/testing/selftests/kvm/x86/private_mem_conversions_test.c @@ -307,7 +307,7 @@ static void handle_exit_hypercall(struct kvm_vcpu *vcpu) vm_guest_mem_fallocate(vm, gpa, size, map_shared); if (set_attributes) - vm_set_memory_attributes(vm, gpa, size, + vm_mem_set_memory_attributes(vm, gpa, size, map_shared ? 0 : KVM_MEMORY_ATTRIBUTE_PRIVATE); run->hypercall.ret = 0; } @@ -382,6 +382,7 @@ static void test_mem_conversions(enum vm_mem_backing_src_type src_type, u32 nr_v const size_t slot_size = memfd_size / nr_memslots; struct kvm_vcpu *vcpus[KVM_MAX_VCPUS]; pthread_t threads[KVM_MAX_VCPUS]; + u64 gmem_flags = 0; struct kvm_vm *vm; int memfd, i; @@ -397,7 +398,10 @@ static void test_mem_conversions(enum vm_mem_backing_src_type src_type, u32 nr_v vm_enable_cap(vm, KVM_CAP_EXIT_HYPERCALL, (1 << KVM_HC_MAP_GPA_RANGE)); - memfd = vm_create_guest_memfd(vm, memfd_size, 0); + if (kvm_has_gmem_attributes) + gmem_flags = GUEST_MEMFD_FLAG_INIT_SHARED; + + memfd = vm_create_guest_memfd(vm, memfd_size, gmem_flags); for (i = 0; i < nr_memslots; i++) vm_mem_add(vm, src_type, BASE_DATA_GPA + slot_size * i,