From: Paolo Bonzini <pbonzini@redhat.com>
To: qemu-devel@nongnu.org
Cc: "Philippe Mathieu-Daudé" <philmd@redhat.com>,
"Eduardo Habkost" <ehabkost@redhat.com>,
"Peter Xu" <peterx@redhat.com>,
"David Hildenbrand" <david@redhat.com>
Subject: [PULL 24/33] util/mmap-alloc: Pass flags instead of separate bools to qemu_ram_mmap()
Date: Tue, 15 Jun 2021 15:38:46 +0200 [thread overview]
Message-ID: <20210615133855.775687-25-pbonzini@redhat.com> (raw)
In-Reply-To: <20210615133855.775687-1-pbonzini@redhat.com>
From: David Hildenbrand <david@redhat.com>
Let's pass flags instead of bools to prepare for passing other flags and
update the documentation of qemu_ram_mmap(). Introduce new QEMU_MAP_
flags that abstract the mmap() PROT_ and MAP_ flag handling and simplify
it.
We expose only flags that are currently supported by qemu_ram_mmap().
Maybe, we'll see qemu_mmap() in the future as well that can implement these
flags.
Note: We don't use MAP_ flags as some flags (e.g., MAP_SYNC) are only
defined for some systems and we want to always be able to identify
these flags reliably inside qemu_ram_mmap() -- for example, to properly
warn when some future flags are not available or effective on a system.
Also, this way we can simplify PROT_ handling as well.
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Acked-by: Eduardo Habkost <ehabkost@redhat.com> for memory backend and machine core
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20210510114328.21835-8-david@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
include/qemu/mmap-alloc.h | 16 +++++++++-------
include/qemu/osdep.h | 18 ++++++++++++++++++
softmmu/physmem.c | 8 +++++---
util/mmap-alloc.c | 15 ++++++++-------
util/oslib-posix.c | 3 ++-
5 files changed, 42 insertions(+), 18 deletions(-)
diff --git a/include/qemu/mmap-alloc.h b/include/qemu/mmap-alloc.h
index 456ff87df1..90d0eee705 100644
--- a/include/qemu/mmap-alloc.h
+++ b/include/qemu/mmap-alloc.h
@@ -7,18 +7,22 @@ size_t qemu_fd_getpagesize(int fd);
size_t qemu_mempath_getpagesize(const char *mem_path);
/**
- * qemu_ram_mmap: mmap the specified file or device.
+ * qemu_ram_mmap: mmap anonymous memory, the specified file or device.
+ *
+ * mmap() abstraction to map guest RAM, simplifying flag handling, taking
+ * care of alignment requirements and installing guard pages.
*
* Parameters:
* @fd: the file or the device to mmap
* @size: the number of bytes to be mmaped
* @align: if not zero, specify the alignment of the starting mapping address;
* otherwise, the alignment in use will be determined by QEMU.
- * @readonly: true for a read-only mapping, false for read/write.
- * @shared: map has RAM_SHARED flag.
- * @is_pmem: map has RAM_PMEM flag.
+ * @qemu_map_flags: QEMU_MAP_* flags
* @map_offset: map starts at offset of map_offset from the start of fd
*
+ * Internally, MAP_PRIVATE, MAP_ANONYMOUS and MAP_SHARED_VALIDATE are set
+ * implicitly based on other parameters.
+ *
* Return:
* On success, return a pointer to the mapped area.
* On failure, return MAP_FAILED.
@@ -26,9 +30,7 @@ size_t qemu_mempath_getpagesize(const char *mem_path);
void *qemu_ram_mmap(int fd,
size_t size,
size_t align,
- bool readonly,
- bool shared,
- bool is_pmem,
+ uint32_t qemu_map_flags,
off_t map_offset);
void qemu_ram_munmap(int fd, void *ptr, size_t size);
diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
index 4c6f2390be..88106e88fc 100644
--- a/include/qemu/osdep.h
+++ b/include/qemu/osdep.h
@@ -366,6 +366,24 @@ void *qemu_anon_ram_alloc(size_t size, uint64_t *align, bool shared);
void qemu_vfree(void *ptr);
void qemu_anon_ram_free(void *ptr, size_t size);
+/*
+ * Abstraction of PROT_ and MAP_ flags as passed to mmap(), for example,
+ * consumed by qemu_ram_mmap().
+ */
+
+/* Map PROT_READ instead of PROT_READ | PROT_WRITE. */
+#define QEMU_MAP_READONLY (1 << 0)
+
+/* Use MAP_SHARED instead of MAP_PRIVATE. */
+#define QEMU_MAP_SHARED (1 << 1)
+
+/*
+ * Use MAP_SYNC | MAP_SHARED_VALIDATE if supported. Ignored without
+ * QEMU_MAP_SHARED. If mapping fails, warn and fallback to !QEMU_MAP_SYNC.
+ */
+#define QEMU_MAP_SYNC (1 << 2)
+
+
#define QEMU_MADV_INVALID -1
#if defined(CONFIG_MADVISE)
diff --git a/softmmu/physmem.c b/softmmu/physmem.c
index f7adf544df..24228c838c 100644
--- a/softmmu/physmem.c
+++ b/softmmu/physmem.c
@@ -1540,6 +1540,7 @@ static void *file_ram_alloc(RAMBlock *block,
off_t offset,
Error **errp)
{
+ uint32_t qemu_map_flags;
void *area;
block->page_size = qemu_fd_getpagesize(fd);
@@ -1587,9 +1588,10 @@ static void *file_ram_alloc(RAMBlock *block,
perror("ftruncate");
}
- area = qemu_ram_mmap(fd, memory, block->mr->align, readonly,
- block->flags & RAM_SHARED, block->flags & RAM_PMEM,
- offset);
+ 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;
+ 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");
diff --git a/util/mmap-alloc.c b/util/mmap-alloc.c
index 0e2bd7bc0e..1ddc0e2a1e 100644
--- a/util/mmap-alloc.c
+++ b/util/mmap-alloc.c
@@ -118,9 +118,12 @@ static void *mmap_reserve(size_t size, int fd)
* Activate memory in a reserved region from the given fd (if any), to make
* it accessible.
*/
-static void *mmap_activate(void *ptr, size_t size, int fd, bool readonly,
- bool shared, bool is_pmem, off_t map_offset)
+static void *mmap_activate(void *ptr, size_t size, int fd,
+ uint32_t qemu_map_flags, off_t map_offset)
{
+ const bool readonly = qemu_map_flags & QEMU_MAP_READONLY;
+ const bool shared = qemu_map_flags & QEMU_MAP_SHARED;
+ const bool sync = qemu_map_flags & QEMU_MAP_SYNC;
const int prot = PROT_READ | (readonly ? 0 : PROT_WRITE);
int map_sync_flags = 0;
int flags = MAP_FIXED;
@@ -128,7 +131,7 @@ static void *mmap_activate(void *ptr, size_t size, int fd, bool readonly,
flags |= fd == -1 ? MAP_ANONYMOUS : 0;
flags |= shared ? MAP_SHARED : MAP_PRIVATE;
- if (shared && is_pmem) {
+ if (shared && sync) {
map_sync_flags = MAP_SYNC | MAP_SHARED_VALIDATE;
}
@@ -173,9 +176,7 @@ static inline size_t mmap_guard_pagesize(int fd)
void *qemu_ram_mmap(int fd,
size_t size,
size_t align,
- bool readonly,
- bool shared,
- bool is_pmem,
+ uint32_t qemu_map_flags,
off_t map_offset)
{
const size_t guard_pagesize = mmap_guard_pagesize(fd);
@@ -199,7 +200,7 @@ void *qemu_ram_mmap(int fd,
offset = QEMU_ALIGN_UP((uintptr_t)guardptr, align) - (uintptr_t)guardptr;
- ptr = mmap_activate(guardptr + offset, size, fd, readonly, shared, is_pmem,
+ ptr = mmap_activate(guardptr + offset, size, fd, qemu_map_flags,
map_offset);
if (ptr == MAP_FAILED) {
munmap(guardptr, total);
diff --git a/util/oslib-posix.c b/util/oslib-posix.c
index 7b4bec1402..0dd7784a88 100644
--- a/util/oslib-posix.c
+++ b/util/oslib-posix.c
@@ -229,8 +229,9 @@ void *qemu_memalign(size_t alignment, size_t size)
/* alloc shared memory pages */
void *qemu_anon_ram_alloc(size_t size, uint64_t *alignment, bool shared)
{
+ const uint32_t qemu_map_flags = shared ? QEMU_MAP_SHARED : 0;
size_t align = QEMU_VMALLOC_ALIGN;
- void *ptr = qemu_ram_mmap(-1, size, align, false, shared, false, 0);
+ void *ptr = qemu_ram_mmap(-1, size, align, qemu_map_flags, 0);
if (ptr == MAP_FAILED) {
return NULL;
--
2.31.1
next prev parent reply other threads:[~2021-06-15 13:53 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-15 13:38 [PULL 00/33] Misc patches for 2021-06-15 Paolo Bonzini
2021-06-15 13:38 ` [PULL 01/33] vnc: avoid deprecation warnings for SASL on OS X Paolo Bonzini
2021-06-15 13:38 ` [PULL 02/33] vl: Fix an assert failure in error path Paolo Bonzini
2021-06-15 13:38 ` [PULL 03/33] qemu-config: use qemu_opts_from_qdict Paolo Bonzini
2021-06-15 13:38 ` [PULL 04/33] block/scsi: correctly emulate the VPD block limits page Paolo Bonzini
2021-06-15 13:38 ` [PULL 05/33] runstate: Initialize Error * to NULL Paolo Bonzini
2021-06-15 13:38 ` [PULL 06/33] esp: only assert INTR_DC interrupt flag if selection fails Paolo Bonzini
2021-06-15 13:38 ` [PULL 07/33] esp: only set ESP_RSEQ at the start of the select sequence Paolo Bonzini
2021-06-15 13:38 ` [PULL 08/33] esp: allow non-DMA callback in esp_transfer_data() initial transfer Paolo Bonzini
2021-06-15 13:38 ` [PULL 09/33] esp: handle non-DMA transfers from the target one byte at a time Paolo Bonzini
2021-06-15 13:38 ` [PULL 10/33] esp: ensure PDMA write transfers are flushed from the FIFO to the target immediately Paolo Bonzini
2021-06-15 13:38 ` [PULL 11/33] esp: revert 75ef849696 "esp: correctly fill bus id with requested lun" Paolo Bonzini
2021-06-15 13:38 ` [PULL 12/33] esp: correctly accumulate extended messages for PDMA Paolo Bonzini
2021-06-15 13:38 ` [PULL 13/33] esp: fix migration version check in esp_is_version_5() Paolo Bonzini
2021-06-15 13:38 ` [PULL 14/33] esp: store lun coming from the MESSAGE OUT phase Paolo Bonzini
2021-06-15 13:38 ` [PULL 15/33] softmmu/physmem: Mark shared anonymous memory RAM_SHARED Paolo Bonzini
2021-06-15 13:38 ` [PULL 16/33] softmmu/physmem: Fix ram_block_discard_range() to handle shared anonymous memory Paolo Bonzini
2021-06-15 13:38 ` [PULL 17/33] softmmu/physmem: Fix qemu_ram_remap() " Paolo Bonzini
2021-06-15 13:38 ` [PULL 18/33] util/mmap-alloc: Factor out calculation of the pagesize for the guard page Paolo Bonzini
2021-06-15 13:38 ` [PULL 19/33] util/mmap-alloc: Factor out reserving of a memory region to mmap_reserve() Paolo Bonzini
2021-06-15 13:38 ` [PULL 20/33] util/mmap-alloc: Factor out activating of memory to mmap_activate() Paolo Bonzini
2021-06-15 13:38 ` [PULL 21/33] softmmu/memory: Pass ram_flags to qemu_ram_alloc_from_fd() Paolo Bonzini
2021-06-15 13:38 ` [PULL 22/33] softmmu/memory: Pass ram_flags to memory_region_init_ram_shared_nomigrate() Paolo Bonzini
2021-06-15 13:38 ` [PULL 23/33] softmmu/memory: Pass ram_flags to qemu_ram_alloc() and qemu_ram_alloc_internal() Paolo Bonzini
2021-06-15 13:38 ` Paolo Bonzini [this message]
2021-06-15 13:38 ` [PULL 25/33] memory: Introduce RAM_NORESERVE and wire it up in qemu_ram_mmap() Paolo Bonzini
2021-06-15 13:38 ` [PULL 26/33] util/mmap-alloc: Support RAM_NORESERVE via MAP_NORESERVE under Linux Paolo Bonzini
2021-06-15 13:38 ` [PULL 27/33] hostmem: Wire up RAM_NORESERVE via "reserve" property Paolo Bonzini
2021-06-15 13:38 ` [PULL 28/33] qmp: Clarify memory backend properties returned via query-memdev Paolo Bonzini
2021-06-15 13:38 ` [PULL 29/33] qmp: Include "share" property of memory backends Paolo Bonzini
2021-06-15 13:38 ` [PULL 30/33] hmp: Print "share" property of memory backends with "info memdev" Paolo Bonzini
2021-06-15 13:38 ` [PULL 31/33] qmp: Include "reserve" property of memory backends Paolo Bonzini
2021-06-15 13:38 ` [PULL 32/33] hmp: Print "reserve" property of memory backends with "info memdev" Paolo Bonzini
2021-06-15 13:38 ` [PULL 33/33] configure: map x32 to cpu_family x86_64 for meson Paolo Bonzini
2021-06-15 14:17 ` [PULL 00/33] Misc patches for 2021-06-15 Peter Maydell
2021-06-15 16:52 ` Philippe Mathieu-Daudé
2021-06-17 10:06 ` Alex Bennée
2021-06-17 12:55 ` Paolo Bonzini
2021-06-17 15:34 ` Thomas Huth
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