From: Sean Christopherson <seanjc@google•com>
To: Paolo Bonzini <pbonzini@redhat•com>,
Marc Zyngier <maz@kernel•org>,
Oliver Upton <oliver.upton@linux•dev>,
Sean Christopherson <seanjc@google•com>
Cc: kvm@vger•kernel.org, linux-arm-kernel@lists•infradead.org,
kvmarm@lists•linux.dev, linux-kernel@vger•kernel.org,
Ira Weiny <ira.weiny@intel•com>, Gavin Shan <gshan@redhat•com>,
Shivank Garg <shivankg@amd•com>,
Vlastimil Babka <vbabka@suse•cz>,
Xiaoyao Li <xiaoyao.li@intel•com>,
David Hildenbrand <david@redhat•com>,
Fuad Tabba <tabba@google•com>,
Ackerley Tng <ackerleytng@google•com>,
Tao Chan <chentao@kylinos•cn>,
James Houghton <jthoughton@google•com>
Subject: [PATCH v17 23/24] KVM: selftests: guest_memfd mmap() test when mmap is supported
Date: Tue, 29 Jul 2025 15:54:54 -0700 [thread overview]
Message-ID: <20250729225455.670324-24-seanjc@google.com> (raw)
In-Reply-To: <20250729225455.670324-1-seanjc@google.com>
From: Fuad Tabba <tabba@google•com>
Expand the guest_memfd selftests to comprehensively test host userspace
mmap functionality for guest_memfd-backed memory when supported by the
VM type.
Introduce new test cases to verify the following:
* Successful mmap operations: Ensure that MAP_SHARED mappings succeed
when guest_memfd mmap is enabled.
* Data integrity: Validate that data written to the mmap'd region is
correctly persistent and readable.
* fallocate interaction: Test that fallocate(FALLOC_FL_PUNCH_HOLE)
correctly zeros out mapped pages.
* Out-of-bounds access: Verify that accessing memory beyond the
guest_memfd's size correctly triggers a SIGBUS signal.
* Unsupported mmap: Confirm that mmap attempts fail as expected when
guest_memfd mmap support is not enabled for the specific guest_memfd
instance or VM type.
* Flag validity: Introduce test_vm_type_gmem_flag_validity() to
systematically test that only allowed guest_memfd creation flags are
accepted for different VM types (e.g., GUEST_MEMFD_FLAG_MMAP for
default VMs, no flags for CoCo VMs).
The existing tests for guest_memfd creation (multiple instances, invalid
sizes), file read/write, file size, and invalid punch hole operations
are integrated into the new test_with_type() framework to allow testing
across different VM types.
Cc: James Houghton <jthoughton@google•com>
Cc: Gavin Shan <gshan@redhat•com>
Cc: Shivank Garg <shivankg@amd•com>
Co-developed-by: Ackerley Tng <ackerleytng@google•com>
Signed-off-by: Ackerley Tng <ackerleytng@google•com>
Signed-off-by: Fuad Tabba <tabba@google•com>
Co-developed-by: Sean Christopherson <seanjc@google•com>
Signed-off-by: Sean Christopherson <seanjc@google•com>
---
.../testing/selftests/kvm/guest_memfd_test.c | 161 +++++++++++++++---
1 file changed, 139 insertions(+), 22 deletions(-)
diff --git a/tools/testing/selftests/kvm/guest_memfd_test.c b/tools/testing/selftests/kvm/guest_memfd_test.c
index 341ba616cf55..088053d5f0f5 100644
--- a/tools/testing/selftests/kvm/guest_memfd_test.c
+++ b/tools/testing/selftests/kvm/guest_memfd_test.c
@@ -13,6 +13,8 @@
#include <linux/bitmap.h>
#include <linux/falloc.h>
+#include <setjmp.h>
+#include <signal.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
@@ -34,12 +36,83 @@ static void test_file_read_write(int fd)
"pwrite on a guest_mem fd should fail");
}
-static void test_mmap(int fd, size_t page_size)
+static void test_mmap_supported(int fd, size_t page_size, size_t total_size)
+{
+ const char val = 0xaa;
+ char *mem;
+ size_t i;
+ int ret;
+
+ mem = mmap(NULL, total_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
+ TEST_ASSERT(mem == MAP_FAILED, "Copy-on-write not allowed by guest_memfd.");
+
+ mem = mmap(NULL, total_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+ TEST_ASSERT(mem != MAP_FAILED, "mmap() for guest_memfd should succeed.");
+
+ memset(mem, val, total_size);
+ for (i = 0; i < total_size; i++)
+ TEST_ASSERT_EQ(READ_ONCE(mem[i]), val);
+
+ ret = fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE, 0,
+ page_size);
+ TEST_ASSERT(!ret, "fallocate the first page should succeed.");
+
+ for (i = 0; i < page_size; i++)
+ TEST_ASSERT_EQ(READ_ONCE(mem[i]), 0x00);
+ for (; i < total_size; i++)
+ TEST_ASSERT_EQ(READ_ONCE(mem[i]), val);
+
+ memset(mem, val, page_size);
+ for (i = 0; i < total_size; i++)
+ TEST_ASSERT_EQ(READ_ONCE(mem[i]), val);
+
+ ret = munmap(mem, total_size);
+ TEST_ASSERT(!ret, "munmap() should succeed.");
+}
+
+static sigjmp_buf jmpbuf;
+void fault_sigbus_handler(int signum)
+{
+ siglongjmp(jmpbuf, 1);
+}
+
+static void test_fault_overflow(int fd, size_t page_size, size_t total_size)
+{
+ struct sigaction sa_old, sa_new = {
+ .sa_handler = fault_sigbus_handler,
+ };
+ size_t map_size = total_size * 4;
+ const char val = 0xaa;
+ char *mem;
+ size_t i;
+ int ret;
+
+ mem = mmap(NULL, map_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+ TEST_ASSERT(mem != MAP_FAILED, "mmap() for guest_memfd should succeed.");
+
+ sigaction(SIGBUS, &sa_new, &sa_old);
+ if (sigsetjmp(jmpbuf, 1) == 0) {
+ memset(mem, 0xaa, map_size);
+ TEST_ASSERT(false, "memset() should have triggered SIGBUS.");
+ }
+ sigaction(SIGBUS, &sa_old, NULL);
+
+ for (i = 0; i < total_size; i++)
+ TEST_ASSERT_EQ(READ_ONCE(mem[i]), val);
+
+ ret = munmap(mem, map_size);
+ TEST_ASSERT(!ret, "munmap() should succeed.");
+}
+
+static void test_mmap_not_supported(int fd, size_t page_size, size_t total_size)
{
char *mem;
mem = mmap(NULL, page_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
TEST_ASSERT_EQ(mem, MAP_FAILED);
+
+ mem = mmap(NULL, total_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+ TEST_ASSERT_EQ(mem, MAP_FAILED);
}
static void test_file_size(int fd, size_t page_size, size_t total_size)
@@ -120,26 +193,19 @@ static void test_invalid_punch_hole(int fd, size_t page_size, size_t total_size)
}
}
-static void test_create_guest_memfd_invalid(struct kvm_vm *vm)
+static void test_create_guest_memfd_invalid_sizes(struct kvm_vm *vm,
+ uint64_t guest_memfd_flags,
+ size_t page_size)
{
- size_t page_size = getpagesize();
- uint64_t flag;
size_t size;
int fd;
for (size = 1; size < page_size; size++) {
- fd = __vm_create_guest_memfd(vm, size, 0);
- TEST_ASSERT(fd == -1 && errno == EINVAL,
+ fd = __vm_create_guest_memfd(vm, size, guest_memfd_flags);
+ TEST_ASSERT(fd < 0 && errno == EINVAL,
"guest_memfd() with non-page-aligned page size '0x%lx' should fail with EINVAL",
size);
}
-
- for (flag = BIT(0); flag; flag <<= 1) {
- fd = __vm_create_guest_memfd(vm, page_size, flag);
- TEST_ASSERT(fd == -1 && errno == EINVAL,
- "guest_memfd() with flag '0x%lx' should fail with EINVAL",
- flag);
- }
}
static void test_create_guest_memfd_multiple(struct kvm_vm *vm)
@@ -171,30 +237,81 @@ static void test_create_guest_memfd_multiple(struct kvm_vm *vm)
close(fd1);
}
-int main(int argc, char *argv[])
+static void test_guest_memfd_flags(struct kvm_vm *vm, uint64_t valid_flags)
{
- size_t page_size;
- size_t total_size;
+ size_t page_size = getpagesize();
+ uint64_t flag;
int fd;
+
+ for (flag = BIT(0); flag; flag <<= 1) {
+ fd = __vm_create_guest_memfd(vm, page_size, flag);
+ if (flag & valid_flags) {
+ TEST_ASSERT(fd >= 0,
+ "guest_memfd() with flag '0x%lx' should succeed",
+ flag);
+ close(fd);
+ } else {
+ TEST_ASSERT(fd < 0 && errno == EINVAL,
+ "guest_memfd() with flag '0x%lx' should fail with EINVAL",
+ flag);
+ }
+ }
+}
+
+static void test_guest_memfd(unsigned long vm_type)
+{
+ uint64_t flags = 0;
struct kvm_vm *vm;
-
- TEST_REQUIRE(kvm_has_cap(KVM_CAP_GUEST_MEMFD));
+ size_t total_size;
+ size_t page_size;
+ int fd;
page_size = getpagesize();
total_size = page_size * 4;
- vm = vm_create_barebones();
+ vm = vm_create_barebones_type(vm_type);
+
+ if (vm_check_cap(vm, KVM_CAP_GUEST_MEMFD_MMAP))
+ flags |= GUEST_MEMFD_FLAG_MMAP;
- test_create_guest_memfd_invalid(vm);
test_create_guest_memfd_multiple(vm);
+ test_create_guest_memfd_invalid_sizes(vm, flags, page_size);
- fd = vm_create_guest_memfd(vm, total_size, 0);
+ fd = vm_create_guest_memfd(vm, total_size, flags);
test_file_read_write(fd);
- test_mmap(fd, page_size);
+
+ if (flags & GUEST_MEMFD_FLAG_MMAP) {
+ test_mmap_supported(fd, page_size, total_size);
+ test_fault_overflow(fd, page_size, total_size);
+ } else {
+ test_mmap_not_supported(fd, page_size, total_size);
+ }
+
test_file_size(fd, page_size, total_size);
test_fallocate(fd, page_size, total_size);
test_invalid_punch_hole(fd, page_size, total_size);
+ test_guest_memfd_flags(vm, flags);
+
close(fd);
+ kvm_vm_free(vm);
+}
+
+int main(int argc, char *argv[])
+{
+ unsigned long vm_types, vm_type;
+
+ TEST_REQUIRE(kvm_has_cap(KVM_CAP_GUEST_MEMFD));
+
+ /*
+ * Not all architectures support KVM_CAP_VM_TYPES. However, those that
+ * support guest_memfd have that support for the default VM type.
+ */
+ vm_types = kvm_check_cap(KVM_CAP_VM_TYPES);
+ if (!vm_types)
+ vm_types = VM_TYPE_DEFAULT;
+
+ for_each_set_bit(vm_type, &vm_types, BITS_PER_TYPE(vm_types))
+ test_guest_memfd(vm_type);
}
--
2.50.1.552.g942d659e1b-goog
next prev parent reply other threads:[~2025-07-29 23:57 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-29 22:54 [PATCH v17 00/24] KVM: Enable mmap() for guest_memfd Sean Christopherson
2025-07-29 22:54 ` [PATCH v17 01/24] KVM: Rename CONFIG_KVM_PRIVATE_MEM to CONFIG_KVM_GUEST_MEMFD Sean Christopherson
2025-07-29 22:54 ` [PATCH v17 02/24] KVM: x86: Have all vendor neutral sub-configs depend on KVM_X86, not just KVM Sean Christopherson
2025-07-31 8:08 ` Fuad Tabba
2025-07-29 22:54 ` [PATCH v17 03/24] KVM: x86: Select KVM_GENERIC_PRIVATE_MEM directly from KVM_SW_PROTECTED_VM Sean Christopherson
2025-07-31 8:08 ` Fuad Tabba
2025-07-29 22:54 ` [PATCH v17 04/24] KVM: x86: Select TDX's KVM_GENERIC_xxx dependencies iff CONFIG_KVM_INTEL_TDX=y Sean Christopherson
2025-07-31 8:07 ` Fuad Tabba
2025-07-29 22:54 ` [PATCH v17 05/24] KVM: Rename CONFIG_KVM_GENERIC_PRIVATE_MEM to CONFIG_HAVE_KVM_ARCH_GMEM_POPULATE Sean Christopherson
2025-07-29 22:54 ` [PATCH v17 06/24] KVM: Rename kvm_slot_can_be_private() to kvm_slot_has_gmem() Sean Christopherson
2025-07-29 22:54 ` [PATCH v17 07/24] KVM: Fix comments that refer to slots_lock Sean Christopherson
2025-07-29 22:54 ` [PATCH v17 08/24] KVM: Fix comment that refers to kvm uapi header path Sean Christopherson
2025-07-29 22:54 ` [PATCH v17 09/24] KVM: x86: Enable KVM_GUEST_MEMFD for all 64-bit builds Sean Christopherson
2025-07-29 22:54 ` [PATCH v17 10/24] KVM: guest_memfd: Add plumbing to host to map guest_memfd pages Sean Christopherson
2025-07-29 22:54 ` [PATCH v17 11/24] KVM: guest_memfd: Track guest_memfd mmap support in memslot Sean Christopherson
2025-07-29 22:54 ` [PATCH v17 12/24] KVM: x86/mmu: Rename .private_max_mapping_level() to .gmem_max_mapping_level() Sean Christopherson
2025-07-31 8:15 ` Fuad Tabba
2025-07-31 8:29 ` David Hildenbrand
2025-07-31 8:33 ` Fuad Tabba
2025-07-29 22:54 ` [PATCH v17 13/24] KVM: x86/mmu: Hoist guest_memfd max level/order helpers "up" in mmu.c Sean Christopherson
2025-07-31 7:59 ` David Hildenbrand
2025-07-31 8:06 ` Fuad Tabba
2025-07-29 22:54 ` [PATCH v17 14/24] KVM: x86/mmu: Enforce guest_memfd's max order when recovering hugepages Sean Christopherson
2025-07-30 7:33 ` Xiaoyao Li
2025-07-31 8:06 ` David Hildenbrand
2025-07-31 8:10 ` Fuad Tabba
2025-07-29 22:54 ` [PATCH v17 15/24] KVM: x86/mmu: Extend guest_memfd's max mapping level to shared mappings Sean Christopherson
2025-07-30 7:36 ` Xiaoyao Li
2025-07-31 8:01 ` David Hildenbrand
2025-07-31 8:05 ` Fuad Tabba
2025-07-29 22:54 ` [PATCH v17 16/24] KVM: x86/mmu: Handle guest page faults for guest_memfd with shared memory Sean Christopherson
2025-07-30 7:37 ` Xiaoyao Li
2025-07-29 22:54 ` [PATCH v17 17/24] KVM: arm64: Refactor user_mem_abort() Sean Christopherson
2025-07-29 22:54 ` [PATCH v17 18/24] KVM: arm64: Handle guest_memfd-backed guest page faults Sean Christopherson
2025-07-29 22:54 ` [PATCH v17 19/24] KVM: arm64: nv: Handle VNCR_EL2-triggered faults backed by guest_memfd Sean Christopherson
2025-07-29 22:54 ` [PATCH v17 20/24] KVM: arm64: Enable support for guest_memfd backed memory Sean Christopherson
2025-07-29 22:54 ` [PATCH v17 21/24] KVM: Allow and advertise support for host mmap() on guest_memfd files Sean Christopherson
2025-07-29 22:54 ` [PATCH v17 22/24] KVM: selftests: Do not use hardcoded page sizes in guest_memfd test Sean Christopherson
2025-07-30 11:04 ` Xiaoyao Li
2025-07-29 22:54 ` Sean Christopherson [this message]
2025-07-30 11:39 ` [PATCH v17 23/24] KVM: selftests: guest_memfd mmap() test when mmap is supported Xiaoyao Li
2025-07-30 12:57 ` Sean Christopherson
2025-07-31 7:49 ` Xiaoyao Li
2025-08-07 8:12 ` Shivank Garg
2025-07-29 22:54 ` [PATCH v17 24/24] KVM: selftests: Add guest_memfd testcase to fault-in on !mmap()'d memory Sean Christopherson
2025-07-30 8:20 ` Xiaoyao Li
2025-07-30 15:51 ` Fuad Tabba
2026-03-30 6:21 ` Zenghui Yu
2026-04-17 16:47 ` Sean Christopherson
2026-05-12 7:28 ` Zenghui Yu
2026-05-12 15:53 ` Sean Christopherson
2025-07-30 21:34 ` [PATCH v17 00/24] KVM: Enable mmap() for guest_memfd Ackerley Tng
2025-07-30 22:44 ` Ackerley Tng
2025-08-27 8:43 ` Paolo Bonzini
2025-08-27 12:57 ` Sean Christopherson
2025-08-27 13:08 ` Marc Zyngier
2025-08-27 13:11 ` Paolo Bonzini
2025-08-27 13:14 ` Marc Zyngier
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20250729225455.670324-24-seanjc@google.com \
--to=seanjc@google$(echo .)com \
--cc=ackerleytng@google$(echo .)com \
--cc=chentao@kylinos$(echo .)cn \
--cc=david@redhat$(echo .)com \
--cc=gshan@redhat$(echo .)com \
--cc=ira.weiny@intel$(echo .)com \
--cc=jthoughton@google$(echo .)com \
--cc=kvm@vger$(echo .)kernel.org \
--cc=kvmarm@lists$(echo .)linux.dev \
--cc=linux-arm-kernel@lists$(echo .)infradead.org \
--cc=linux-kernel@vger$(echo .)kernel.org \
--cc=maz@kernel$(echo .)org \
--cc=oliver.upton@linux$(echo .)dev \
--cc=pbonzini@redhat$(echo .)com \
--cc=shivankg@amd$(echo .)com \
--cc=tabba@google$(echo .)com \
--cc=vbabka@suse$(echo .)cz \
--cc=xiaoyao.li@intel$(echo .)com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox