From: Marc-André Lureau <marcandre.lur...@redhat.com> Rewrite get_next_page() to work over non-aligned blocks. When it encounters non aligned addresses, it will allocate a zero-page and try to fill it.
This solves a kdump crash with "tpm-crb-cmd" RAM memory region, qemu-kvm: ../dump/dump.c:1162: _Bool get_next_page(GuestPhysBlock **, uint64_t *, uint8_t **, DumpState *): Assertion `(block->target_start & ~target_page_mask) == 0' failed. because: guest_phys_block_add_section: target_start=00000000fed40080 target_end=00000000fed41000: added (count: 4) Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=2120480 Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com> --- dump/dump.c | 89 ++++++++++++++++++++++++++++++++++++++--------------- 1 file changed, 64 insertions(+), 25 deletions(-) diff --git a/dump/dump.c b/dump/dump.c index 18f06cffe2..9aeed88688 100644 --- a/dump/dump.c +++ b/dump/dump.c @@ -1094,49 +1094,79 @@ static uint64_t dump_pfn_to_paddr(DumpState *s, uint64_t pfn) } /* - * exam every page and return the page frame number and the address of the page. - * bufptr can be NULL. note: the blocks here is supposed to reflect guest-phys - * blocks, so block->target_start and block->target_end should be interal - * multiples of the target page size. + * Return the page frame number and the page content in *bufptr. + * bufptr and allocptr can be NULL. If alloced, *bufptr must be freed. */ static bool get_next_page(GuestPhysBlock **blockptr, uint64_t *pfnptr, - uint8_t **bufptr, DumpState *s) + uint8_t **bufptr, bool *allocptr, DumpState *s) { GuestPhysBlock *block = *blockptr; - hwaddr addr, target_page_mask = ~((hwaddr)s->dump_info.page_size - 1); - uint8_t *buf; + uint32_t page_size = s->dump_info.page_size; + bool alloced = false; + uint8_t *buf = NULL, *hbuf; + hwaddr addr; /* block == NULL means the start of the iteration */ if (block == NULL) { *blockptr = block = QTAILQ_FIRST(&s->guest_phys_blocks.head); addr = block->target_start; + *pfnptr = dump_paddr_to_pfn(s, addr); } else { - addr = dump_pfn_to_paddr(s, *pfnptr + 1); + assert(block != NULL); + *pfnptr += 1; + addr = dump_pfn_to_paddr(s, *pfnptr); } assert(block != NULL); - if ((addr >= block->target_start) && - (addr + s->dump_info.page_size <= block->target_end)) { - buf = block->host_addr + (addr - block->target_start); - } else { - /* the next page is in the next block */ - *blockptr = block = QTAILQ_NEXT(block, next); - if (!block) { - return false; + while (1) { + if (addr >= block->target_start && addr < block->target_end) { + size_t n = MIN(block->target_end - addr, page_size - addr % page_size); + hbuf = block->host_addr + (addr - block->target_start); + if (!alloced) { + if (n == page_size) { + /* this is a whole host page, go for it */ + assert(addr % page_size == 0); + buf = hbuf; + break; + } else { + buf = g_malloc0(page_size); + alloced = true; + } + } + + memcpy(buf + addr % page_size, hbuf, n); + addr += n; + if (addr % page_size == 0) { + /* we filled up the alloc page */ + break; + } + } else { + /* the next page is in the next block */ + *blockptr = block = QTAILQ_NEXT(block, next); + if (!block) { + break; + } + + addr = block->target_start; + /* are we still in the same page? */ + if (dump_paddr_to_pfn(s, addr) != *pfnptr) { + if (alloced) { + /* no, but we already filled something earlier, return it */ + break; + } else { + /* else continue from there */ + *pfnptr = dump_paddr_to_pfn(s, addr); + } + } } - addr = block->target_start; - buf = block->host_addr; } - /* those checks are going away next */ - assert((block->target_start & ~target_page_mask) == 0); - assert((block->target_end & ~target_page_mask) == 0); - *pfnptr = dump_paddr_to_pfn(s, addr); if (bufptr) { *bufptr = buf; + *allocptr = alloced; } - return true; + return buf != NULL; } static void write_dump_bitmap(DumpState *s, Error **errp) @@ -1159,7 +1189,7 @@ static void write_dump_bitmap(DumpState *s, Error **errp) * exam memory page by page, and set the bit in dump_bitmap corresponded * to the existing page. */ - while (get_next_page(&block_iter, &pfn, NULL, s)) { + while (get_next_page(&block_iter, &pfn, NULL, NULL, s)) { ret = set_dump_bitmap(last_pfn, pfn, true, dump_bitmap_buf, s); if (ret < 0) { error_setg(errp, "dump: failed to set dump_bitmap"); @@ -1274,6 +1304,7 @@ static void write_dump_pages(DumpState *s, Error **errp) uint8_t *buf; GuestPhysBlock *block_iter = NULL; uint64_t pfn_iter; + bool freebuf = false; /* get offset of page_desc and page_data in dump file */ offset_desc = s->offset_page; @@ -1314,7 +1345,7 @@ static void write_dump_pages(DumpState *s, Error **errp) * dump memory to vmcore page by page. zero page will all be resided in the * first page of page section */ - while (get_next_page(&block_iter, &pfn_iter, &buf, s)) { + while (get_next_page(&block_iter, &pfn_iter, &buf, &freebuf, s)) { /* check zero page */ if (buffer_is_zero(buf, s->dump_info.page_size)) { ret = write_cache(&page_desc, &pd_zero, sizeof(PageDescriptor), @@ -1403,6 +1434,10 @@ static void write_dump_pages(DumpState *s, Error **errp) error_setg(errp, "dump: failed to write page desc"); goto out; } + if (freebuf) { + g_free(buf); + freebuf = false; + } } s->written_size += s->dump_info.page_size; } @@ -1419,6 +1454,10 @@ static void write_dump_pages(DumpState *s, Error **errp) } out: + if (freebuf) { + g_free(buf); + } + free_data_cache(&page_desc); free_data_cache(&page_data); -- 2.37.2
