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charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260807-gmem-inplace-conversion-v10-40-2fc18ee6d3ba@google.com> References: <20260807-gmem-inplace-conversion-v10-0-2fc18ee6d3ba@google.com> In-Reply-To: <20260807-gmem-inplace-conversion-v10-0-2fc18ee6d3ba@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 , John Hubbard , Peter Xu , tarunsahu@google.com, 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=1786139565; l=5301; i=ackerleytng@google.com; s=20260225; h=from:subject:message-id; bh=xs7fMwhgiH9Gq4d5OQ8oMbU9kMWBZd1SpkQeGjCZdt0=; b=xP2hZKeAJgSYqRy2w9Lz3AIrUj/JbXRETp2w1AQAHaWJdlfgRuY4D3v8O108f4UCAr37nhXB1 bmZHa7GmumwCY5zwoFF7pOTmIg20oysrFZ+iq5GiWk8se8Fz4Guzsbv 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 X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 317E620005 X-Stat-Signature: 591u7f4upzjwtqfaca6s9opi4b3os1ow X-Rspam-User: X-HE-Tag: 1786139588-233250 X-HE-Meta: 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 xo3YRCZg 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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. 2. With in-place conversions, the host's mapping points directly to the guest's memory. When the guest converts a region to private, host access to that region is blocked. Update the test to expect a SIGBUS when attempting to access the host virtual address (HVA) of private memory. 3. Use vm_mem_set_memory_attributes(), which chooses how to set memory attributes based on whether kvm_has_gmem_attributes. Restrict the test to using VM_MEM_SRC_SHMEM because guest_memfd's required mmap() flags and page sizes happens to align with those of VM_MEM_SRC_SHMEM. As long as VM_MEM_SRC_SHMEM is used for src_type, vm_mem_add() works as intended. Co-developed-by: Sean Christopherson Signed-off-by: Sean Christopherson Reviewed-by: Fuad Tabba Tested-by: Shivank Garg Signed-off-by: Ackerley Tng --- .../kvm/x86/private_mem_conversions_test.c | 44 ++++++++++++++++++---- 1 file changed, 36 insertions(+), 8 deletions(-) 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 cf50e9a332c5b..2af8d41963816 100644 --- a/tools/testing/selftests/kvm/x86/private_mem_conversions_test.c +++ b/tools/testing/selftests/kvm/x86/private_mem_conversions_test.c @@ -306,9 +306,12 @@ static void handle_exit_hypercall(struct kvm_vcpu *vcpu) if (do_fallocate) vm_guest_mem_fallocate(vm, gpa, size, map_shared); - if (set_attributes) - vm_set_memory_attributes(vm, gpa, size, - map_shared ? 0 : KVM_MEMORY_ATTRIBUTE_PRIVATE); + if (set_attributes) { + u64 attrs = map_shared ? 0 : KVM_MEMORY_ATTRIBUTE_PRIVATE; + + vm_mem_set_memory_attributes(vm, gpa, size, attrs); + } + run->hypercall.ret = 0; } @@ -352,8 +355,20 @@ static void *__test_mem_conversions(void *__vcpu) size_t nr_bytes = min_t(size_t, vm->page_size, size - i); u8 *hva = addr_gpa2hva(vm, gpa + i); - /* In all cases, the host should observe the shared data. */ - memcmp_h(hva, gpa + i, uc.args[3], nr_bytes); + /* + * When using per-guest_memfd memory attributes, + * i.e. in-place conversion, host accesses will + * point at guest memory and should SIGBUS when + * guest memory is private. When using per-VM + * attributes, i.e. separate backing for shared + * vs. private, the host should always observe + * the shared data. + */ + if (kvm_has_gmem_attributes && + uc.args[0] == SYNC_PRIVATE) + TEST_EXPECT_SIGBUS(READ_ONCE(*hva)); + else + memcmp_h(hva, gpa + i, uc.args[3], nr_bytes); /* For shared, write the new pattern to guest memory. */ if (uc.args[0] == SYNC_SHARED) @@ -382,6 +397,7 @@ 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; struct kvm_vm *vm; int memfd, i; @@ -397,12 +413,17 @@ 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_MMAP | GUEST_MEMFD_FLAG_INIT_SHARED; + else + gmem_flags = 0; + + 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, BASE_DATA_SLOT + i, slot_size / vm->page_size, - KVM_MEM_GUEST_MEMFD, memfd, slot_size * i, 0); + KVM_MEM_GUEST_MEMFD, memfd, slot_size * i, gmem_flags); for (i = 0; i < nr_vcpus; i++) { gpa_t gpa = BASE_DATA_GPA + i * per_cpu_size; @@ -452,17 +473,24 @@ static void usage(const char *cmd) int main(int argc, char *argv[]) { - enum vm_mem_backing_src_type src_type = DEFAULT_VM_MEM_SRC; + enum vm_mem_backing_src_type src_type; u32 nr_memslots = 1; u32 nr_vcpus = 1; int opt; TEST_REQUIRE(kvm_check_cap(KVM_CAP_VM_TYPES) & BIT(KVM_X86_SW_PROTECTED_VM)); + src_type = kvm_has_gmem_attributes ? VM_MEM_SRC_SHMEM : + DEFAULT_VM_MEM_SRC; + while ((opt = getopt(argc, argv, "hm:s:n:")) != -1) { switch (opt) { case 's': src_type = parse_backing_src_type(optarg); + TEST_ASSERT(!kvm_has_gmem_attributes || + src_type == VM_MEM_SRC_SHMEM, + "Testing in-place conversions, only %s mem_type supported\n", + vm_mem_backing_src_alias(VM_MEM_SRC_SHMEM)->name); break; case 'n': nr_vcpus = atoi_positive("nr_vcpus", optarg); -- 2.55.0.654.g21b8a5bc05-goog