| Message ID | 20250127213107.3454680-3-william.roche@oracle.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Poisoned memory recovery on reboot | expand |
On 27.01.25 22:31, “William Roche wrote: > From: William Roche <william.roche@oracle.com> > > Repair poisoned memory location(s), calling ram_block_discard_range(): > punching a hole in the backend file when necessary and regenerating > a usable memory. > If the kernel doesn't support the madvise calls used by this function > and we are dealing with anonymous memory, fall back to remapping the > location(s). > > Signed-off-by: William Roche <william.roche@oracle.com> > --- > system/physmem.c | 54 ++++++++++++++++++++++++++++-------------------- > 1 file changed, 32 insertions(+), 22 deletions(-) > > diff --git a/system/physmem.c b/system/physmem.c > index 3dd2adde73..3dc10ae27b 100644 > --- a/system/physmem.c > +++ b/system/physmem.c > @@ -2167,6 +2167,23 @@ void qemu_ram_free(RAMBlock *block) > } > > #ifndef _WIN32 > +/* Simply remap the given VM memory location from start to start+length */ > +static int qemu_ram_remap_mmap(RAMBlock *block, uint64_t start, size_t length) > +{ > + int flags, prot; > + void *area; > + void *host_startaddr = block->host + start; > + > + assert(block->fd < 0); > + flags = MAP_FIXED | MAP_ANONYMOUS; > + flags |= block->flags & RAM_SHARED ? MAP_SHARED : MAP_PRIVATE; > + flags |= block->flags & RAM_NORESERVE ? MAP_NORESERVE : 0; > + prot = PROT_READ; > + prot |= block->flags & RAM_READONLY ? 0 : PROT_WRITE; > + area = mmap(host_startaddr, length, prot, flags, -1, 0); > + return area != host_startaddr ? -errno : 0; > +} > + > /* > * qemu_ram_remap - remap a single RAM page > * > @@ -2184,9 +2201,7 @@ void qemu_ram_remap(ram_addr_t addr) > { > RAMBlock *block; > uint64_t offset; > - int flags; > - void *area, *vaddr; > - int prot; > + void *vaddr; > size_t page_size; > > RAMBLOCK_FOREACH(block) { > @@ -2201,25 +2216,20 @@ void qemu_ram_remap(ram_addr_t addr) > ; > } else if (xen_enabled()) { > abort(); > - } else { > - flags = MAP_FIXED; > - flags |= block->flags & RAM_SHARED ? > - MAP_SHARED : MAP_PRIVATE; > - flags |= block->flags & RAM_NORESERVE ? MAP_NORESERVE : 0; > - prot = PROT_READ; > - prot |= block->flags & RAM_READONLY ? 0 : PROT_WRITE; > - if (block->fd >= 0) { > - area = mmap(vaddr, page_size, prot, flags, block->fd, > - offset + block->fd_offset); > - } else { > - flags |= MAP_ANONYMOUS; > - area = mmap(vaddr, page_size, prot, flags, -1, 0); > - } > - if (area != vaddr) { > - error_report("Could not remap RAM %s:%" PRIx64 "+%" PRIx64 > - " +%zx", block->idstr, offset, > - block->fd_offset, page_size); > - exit(1); > + if (ram_block_discard_range(block, offset, page_size) != 0) { > + /* > + * Fall back to using mmap() only for anonymous mapping, > + * as if a backing file is associated we may not be able > + * to recover the memory in all cases. > + * So don't take the risk of using only mmap and fail now. > + */ > + if (block->fd >= 0 || > + qemu_ram_remap_mmap(block, offset, page_size) != 0) { > + error_report("Could not remap RAM %s:%" PRIx64 "+%" > + PRIx64 " +%zx", block->idstr, offset, > + block->fd_offset, page_size); > + exit(1); > + } > } > memory_try_enable_merging(vaddr, page_size); > qemu_ram_setup_dump(vaddr, page_size); Acked-by: David Hildenbrand <david@redhat.com>
diff --git a/system/physmem.c b/system/physmem.c index 3dd2adde73..3dc10ae27b 100644 --- a/system/physmem.c +++ b/system/physmem.c @@ -2167,6 +2167,23 @@ void qemu_ram_free(RAMBlock *block) } #ifndef _WIN32 +/* Simply remap the given VM memory location from start to start+length */ +static int qemu_ram_remap_mmap(RAMBlock *block, uint64_t start, size_t length) +{ + int flags, prot; + void *area; + void *host_startaddr = block->host + start; + + assert(block->fd < 0); + flags = MAP_FIXED | MAP_ANONYMOUS; + flags |= block->flags & RAM_SHARED ? MAP_SHARED : MAP_PRIVATE; + flags |= block->flags & RAM_NORESERVE ? MAP_NORESERVE : 0; + prot = PROT_READ; + prot |= block->flags & RAM_READONLY ? 0 : PROT_WRITE; + area = mmap(host_startaddr, length, prot, flags, -1, 0); + return area != host_startaddr ? -errno : 0; +} + /* * qemu_ram_remap - remap a single RAM page * @@ -2184,9 +2201,7 @@ void qemu_ram_remap(ram_addr_t addr) { RAMBlock *block; uint64_t offset; - int flags; - void *area, *vaddr; - int prot; + void *vaddr; size_t page_size; RAMBLOCK_FOREACH(block) { @@ -2201,25 +2216,20 @@ void qemu_ram_remap(ram_addr_t addr) ; } else if (xen_enabled()) { abort(); - } else { - flags = MAP_FIXED; - flags |= block->flags & RAM_SHARED ? - MAP_SHARED : MAP_PRIVATE; - flags |= block->flags & RAM_NORESERVE ? MAP_NORESERVE : 0; - prot = PROT_READ; - prot |= block->flags & RAM_READONLY ? 0 : PROT_WRITE; - if (block->fd >= 0) { - area = mmap(vaddr, page_size, prot, flags, block->fd, - offset + block->fd_offset); - } else { - flags |= MAP_ANONYMOUS; - area = mmap(vaddr, page_size, prot, flags, -1, 0); - } - if (area != vaddr) { - error_report("Could not remap RAM %s:%" PRIx64 "+%" PRIx64 - " +%zx", block->idstr, offset, - block->fd_offset, page_size); - exit(1); + if (ram_block_discard_range(block, offset, page_size) != 0) { + /* + * Fall back to using mmap() only for anonymous mapping, + * as if a backing file is associated we may not be able + * to recover the memory in all cases. + * So don't take the risk of using only mmap and fail now. + */ + if (block->fd >= 0 || + qemu_ram_remap_mmap(block, offset, page_size) != 0) { + error_report("Could not remap RAM %s:%" PRIx64 "+%" + PRIx64 " +%zx", block->idstr, offset, + block->fd_offset, page_size); + exit(1); + } } memory_try_enable_merging(vaddr, page_size); qemu_ram_setup_dump(vaddr, page_size);