On 22.10.24 23:35, “William Roche wrote:
From: William Roche <william.ro...@oracle.com>When the VM reboots, a memory reset is performed calling qemu_ram_remap() on all hwpoisoned pages. While we take into account the recorded page sizes to repair the memory locations, a large page also needs to punch a hole in the backend file to regenerate a usable memory, cleaning the HW poisoned section. This is mandatory for hugetlbfs case for example. Signed-off-by: William Roche <william.ro...@oracle.com> --- system/physmem.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/system/physmem.c b/system/physmem.c index 3757428336..3f6024a92d 100644 --- a/system/physmem.c +++ b/system/physmem.c @@ -2211,6 +2211,14 @@ void qemu_ram_remap(ram_addr_t addr, ram_addr_t length) prot = PROT_READ; prot |= block->flags & RAM_READONLY ? 0 : PROT_WRITE; if (block->fd >= 0) { + if (length > TARGET_PAGE_SIZE && fallocate(block->fd, + FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE, + offset + block->fd_offset, length) != 0) { + error_report("Could not recreate the file hole for " + "addr: " RAM_ADDR_FMT "@" RAM_ADDR_FMT "", + length, addr); + exit(1); + } area = mmap(vaddr, length, prot, flags, block->fd, offset + block->fd_offset); } else {
Ah! Just what I commented to patch #3; we should be using ram_discard_range(). It might be better to avoid the mmap() completely if ram_discard_range() worked.
And as raised, there is the problem with memory preallocation (where we should fail if it doesn't work) and ram discards being disabled because something relies on long-term page pinning ...
-- Cheers, David / dhildenb
