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Date: Thu, 11 Nov 2021 22:13:47 +0800
From: Chao Peng <chao.p.peng@...ux.intel.com>
To: kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-mm@...ck.org, linux-fsdevel@...r.kernel.org,
qemu-devel@...gnu.org
Cc: Paolo Bonzini <pbonzini@...hat.com>,
Jonathan Corbet <corbet@....net>,
Sean Christopherson <seanjc@...gle.com>,
Vitaly Kuznetsov <vkuznets@...hat.com>,
Wanpeng Li <wanpengli@...cent.com>,
Jim Mattson <jmattson@...gle.com>,
Joerg Roedel <joro@...tes.org>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
x86@...nel.org, "H . Peter Anvin" <hpa@...or.com>,
Hugh Dickins <hughd@...gle.com>,
Jeff Layton <jlayton@...nel.org>,
"J . Bruce Fields" <bfields@...ldses.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Yu Zhang <yu.c.zhang@...ux.intel.com>,
Chao Peng <chao.p.peng@...ux.intel.com>,
"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
luto@...nel.org, john.ji@...el.com, susie.li@...el.com,
jun.nakajima@...el.com, dave.hansen@...el.com, ak@...ux.intel.com,
david@...hat.com
Subject: [RFC PATCH 08/13] hostmem: Add guest private memory to memory backend
Currently only memfd is supported.
Signed-off-by: Chao Peng <chao.p.peng@...ux.intel.com>
---
backends/hostmem-memfd.c | 12 +++++++++---
backends/hostmem.c | 24 ++++++++++++++++++++++++
include/exec/memory.h | 3 +++
include/exec/ram_addr.h | 3 ++-
include/qemu/memfd.h | 5 +++++
include/sysemu/hostmem.h | 1 +
softmmu/physmem.c | 33 +++++++++++++++++++--------------
util/memfd.c | 32 +++++++++++++++++++++++++-------
8 files changed, 88 insertions(+), 25 deletions(-)
diff --git a/backends/hostmem-memfd.c b/backends/hostmem-memfd.c
index 3fc85c3db8..ef057586a0 100644
--- a/backends/hostmem-memfd.c
+++ b/backends/hostmem-memfd.c
@@ -36,6 +36,7 @@ memfd_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
{
HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(backend);
uint32_t ram_flags;
+ unsigned int seals;
char *name;
int fd;
@@ -44,10 +45,14 @@ memfd_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
return;
}
+ seals = backend->guest_private ? F_SEAL_GUEST : 0;
+
+ if (m->seal) {
+ seals |= F_SEAL_GROW | F_SEAL_SHRINK | F_SEAL_SEAL;
+ }
+
fd = qemu_memfd_create(TYPE_MEMORY_BACKEND_MEMFD, backend->size,
- m->hugetlb, m->hugetlbsize, m->seal ?
- F_SEAL_GROW | F_SEAL_SHRINK | F_SEAL_SEAL : 0,
- errp);
+ m->hugetlb, m->hugetlbsize, seals, errp);
if (fd == -1) {
return;
}
@@ -55,6 +60,7 @@ memfd_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
name = host_memory_backend_get_name(backend);
ram_flags = backend->share ? RAM_SHARED : 0;
ram_flags |= backend->reserve ? 0 : RAM_NORESERVE;
+ ram_flags |= backend->guest_private ? RAM_GUEST_PRIVATE : 0;
memory_region_init_ram_from_fd(&backend->mr, OBJECT(backend), name,
backend->size, ram_flags, fd, 0, errp);
g_free(name);
diff --git a/backends/hostmem.c b/backends/hostmem.c
index 4c05862ed5..a90d1be0a0 100644
--- a/backends/hostmem.c
+++ b/backends/hostmem.c
@@ -472,6 +472,23 @@ host_memory_backend_set_use_canonical_path(Object *obj, bool value,
backend->use_canonical_path = value;
}
+static bool
+host_memory_backend_get_guest_private(Object *obj, Error **errp)
+{
+ HostMemoryBackend *backend = MEMORY_BACKEND(obj);
+
+ return backend->guest_private;
+
+}
+
+static void
+host_memory_backend_set_guest_private(Object *obj, bool value, Error **errp)
+{
+ HostMemoryBackend *backend = MEMORY_BACKEND(obj);
+
+ backend->guest_private = value;
+}
+
static void
host_memory_backend_class_init(ObjectClass *oc, void *data)
{
@@ -542,6 +559,13 @@ host_memory_backend_class_init(ObjectClass *oc, void *data)
object_class_property_add_bool(oc, "x-use-canonical-path-for-ramblock-id",
host_memory_backend_get_use_canonical_path,
host_memory_backend_set_use_canonical_path);
+
+ object_class_property_add_bool(oc, "guest-private",
+ host_memory_backend_get_guest_private,
+ host_memory_backend_set_guest_private);
+ object_class_property_set_description(oc, "guest-private",
+ "Guest private memory");
+
}
static const TypeInfo host_memory_backend_info = {
diff --git a/include/exec/memory.h b/include/exec/memory.h
index c3d417d317..ae9d3bc574 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -190,6 +190,9 @@ typedef struct IOMMUTLBEvent {
*/
#define RAM_NORESERVE (1 << 7)
+/* RAM is guest private memory that can not be mmap-ed. */
+#define RAM_GUEST_PRIVATE (1 << 8)
+
static inline void iommu_notifier_init(IOMMUNotifier *n, IOMMUNotify fn,
IOMMUNotifierFlag flags,
hwaddr start, hwaddr end,
diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h
index 551876bed0..32768291de 100644
--- a/include/exec/ram_addr.h
+++ b/include/exec/ram_addr.h
@@ -74,7 +74,8 @@ static inline bool clear_bmap_test_and_clear(RAMBlock *rb, uint64_t page)
static inline bool offset_in_ramblock(RAMBlock *b, ram_addr_t offset)
{
- return (b && b->host && offset < b->used_length) ? true : false;
+ return (b && (b->flags & RAM_GUEST_PRIVATE || b->host)
+ && offset < b->used_length) ? true : false;
}
static inline void *ramblock_ptr(RAMBlock *block, ram_addr_t offset)
diff --git a/include/qemu/memfd.h b/include/qemu/memfd.h
index 975b6bdb77..f021a0730a 100644
--- a/include/qemu/memfd.h
+++ b/include/qemu/memfd.h
@@ -14,6 +14,11 @@
#define F_SEAL_SHRINK 0x0002 /* prevent file from shrinking */
#define F_SEAL_GROW 0x0004 /* prevent file from growing */
#define F_SEAL_WRITE 0x0008 /* prevent writes */
+
+#endif
+
+#ifndef F_SEAL_GUEST
+#define F_SEAL_GUEST 0x0020 /* guest private memory */
#endif
#ifndef MFD_CLOEXEC
diff --git a/include/sysemu/hostmem.h b/include/sysemu/hostmem.h
index 9ff5c16963..ddf742a69b 100644
--- a/include/sysemu/hostmem.h
+++ b/include/sysemu/hostmem.h
@@ -65,6 +65,7 @@ struct HostMemoryBackend {
uint64_t size;
bool merge, dump, use_canonical_path;
bool prealloc, is_mapped, share, reserve;
+ bool guest_private;
uint32_t prealloc_threads;
DECLARE_BITMAP(host_nodes, MAX_NODES + 1);
HostMemPolicy policy;
diff --git a/softmmu/physmem.c b/softmmu/physmem.c
index 23e77cb771..f4d6eeaa17 100644
--- a/softmmu/physmem.c
+++ b/softmmu/physmem.c
@@ -1591,15 +1591,19 @@ static void *file_ram_alloc(RAMBlock *block,
perror("ftruncate");
}
- qemu_map_flags = readonly ? QEMU_MAP_READONLY : 0;
- qemu_map_flags |= (block->flags & RAM_SHARED) ? QEMU_MAP_SHARED : 0;
- qemu_map_flags |= (block->flags & RAM_PMEM) ? QEMU_MAP_SYNC : 0;
- qemu_map_flags |= (block->flags & RAM_NORESERVE) ? QEMU_MAP_NORESERVE : 0;
- area = qemu_ram_mmap(fd, memory, block->mr->align, qemu_map_flags, offset);
- if (area == MAP_FAILED) {
- error_setg_errno(errp, errno,
- "unable to map backing store for guest RAM");
- return NULL;
+ if (block->flags & RAM_GUEST_PRIVATE) {
+ area = (void*)offset;
+ } else {
+ qemu_map_flags = readonly ? QEMU_MAP_READONLY : 0;
+ qemu_map_flags |= (block->flags & RAM_SHARED) ? QEMU_MAP_SHARED : 0;
+ qemu_map_flags |= (block->flags & RAM_PMEM) ? QEMU_MAP_SYNC : 0;
+ qemu_map_flags |= (block->flags & RAM_NORESERVE) ? QEMU_MAP_NORESERVE : 0;
+ area = qemu_ram_mmap(fd, memory, block->mr->align, qemu_map_flags, offset);
+ if (area == MAP_FAILED) {
+ error_setg_errno(errp, errno,
+ "unable to map backing store for guest RAM");
+ return NULL;
+ }
}
block->fd = fd;
@@ -1971,7 +1975,7 @@ static void ram_block_add(RAMBlock *new_block, Error **errp)
qemu_mutex_lock_ramlist();
new_block->offset = find_ram_offset(new_block->max_length);
- if (!new_block->host) {
+ if (!new_block->host && !(new_block->flags & RAM_GUEST_PRIVATE)) {
if (xen_enabled()) {
xen_ram_alloc(new_block->offset, new_block->max_length,
new_block->mr, &err);
@@ -2028,7 +2032,7 @@ static void ram_block_add(RAMBlock *new_block, Error **errp)
new_block->used_length,
DIRTY_CLIENTS_ALL);
- if (new_block->host) {
+ if (new_block->host && !(new_block->flags & RAM_GUEST_PRIVATE)) {
qemu_ram_setup_dump(new_block->host, new_block->max_length);
qemu_madvise(new_block->host, new_block->max_length, QEMU_MADV_HUGEPAGE);
/*
@@ -2055,7 +2059,8 @@ RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr,
int64_t file_size, file_align;
/* Just support these ram flags by now. */
- assert((ram_flags & ~(RAM_SHARED | RAM_PMEM | RAM_NORESERVE)) == 0);
+ assert((ram_flags & ~(RAM_SHARED | RAM_PMEM | RAM_NORESERVE |
+ RAM_GUEST_PRIVATE)) == 0);
if (xen_enabled()) {
error_setg(errp, "-mem-path not supported with Xen");
@@ -2092,7 +2097,7 @@ RAMBlock *qemu_ram_alloc_from_fd(ram_addr_t size, MemoryRegion *mr,
new_block->flags = ram_flags;
new_block->host = file_ram_alloc(new_block, size, fd, readonly,
!file_size, offset, errp);
- if (!new_block->host) {
+ if (!new_block->host && !(ram_flags & RAM_GUEST_PRIVATE)) {
g_free(new_block);
return NULL;
}
@@ -2392,7 +2397,7 @@ RAMBlock *qemu_ram_block_from_host(void *ptr, bool round_offset,
RAMBLOCK_FOREACH(block) {
/* This case append when the block is not mapped. */
- if (block->host == NULL) {
+ if (block->host == NULL && !(block->flags & RAM_GUEST_PRIVATE)) {
continue;
}
if (host - block->host < block->max_length) {
diff --git a/util/memfd.c b/util/memfd.c
index 4a3c07e0be..3b4b88d81e 100644
--- a/util/memfd.c
+++ b/util/memfd.c
@@ -76,14 +76,32 @@ int qemu_memfd_create(const char *name, size_t size, bool hugetlb,
goto err;
}
- if (ftruncate(mfd, size) == -1) {
- error_setg_errno(errp, errno, "failed to resize memfd to %zu", size);
- goto err;
- }
- if (seals && fcntl(mfd, F_ADD_SEALS, seals) == -1) {
- error_setg_errno(errp, errno, "failed to add seals 0x%x", seals);
- goto err;
+ /*
+ * The call sequence of F_ADD_SEALS and ftruncate matters here.
+ * For SEAL_GUEST, it requires the size to be 0 at the time of setting seal
+ * For SEAL_GROW/SHRINK, ftruncate should be called before setting seal.
+ */
+ if (seals & F_SEAL_GUEST) {
+ if (seals && fcntl(mfd, F_ADD_SEALS, seals) == -1) {
+ error_setg_errno(errp, errno, "failed to add seals 0x%x", seals);
+ goto err;
+ }
+
+ if (ftruncate(mfd, size) == -1) {
+ error_setg_errno(errp, errno, "failed to resize memfd to %zu", size);
+ goto err;
+ }
+ } else {
+ if (ftruncate(mfd, size) == -1) {
+ error_setg_errno(errp, errno, "failed to resize memfd to %zu", size);
+ goto err;
+ }
+
+ if (seals && fcntl(mfd, F_ADD_SEALS, seals) == -1) {
+ error_setg_errno(errp, errno, "failed to add seals 0x%x", seals);
+ goto err;
+ }
}
return mfd;
--
2.17.1
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