On 05.09.22 14:57, [email protected] wrote:
From: Marc-André Lureau <[email protected]>
Rewrite get_next_page() to work over non-aligned blocks. When it
encounters non aligned addresses, it will try to fill a page provided by
the caller.
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 <[email protected]>
---
dump/dump.c | 79 +++++++++++++++++++++++++++++++++++++----------------
1 file changed, 56 insertions(+), 23 deletions(-)
diff --git a/dump/dump.c b/dump/dump.c
index f465830371..500357bafe 100644
--- a/dump/dump.c
+++ b/dump/dump.c
@@ -1094,50 +1094,81 @@ 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 can be
+ * NULL. If not NULL, *bufptr must contains a target page size of pre-allocated
+ * memory. This is not necessarily the memory returned.
*/
static bool get_next_page(GuestPhysBlock **blockptr, uint64_t *pfnptr,
uint8_t **bufptr, 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;
+ uint8_t *buf = NULL, *hbuf;
+ hwaddr addr;
/* block == NULL means the start of the iteration */
if (!block) {
block = QTAILQ_FIRST(&s->guest_phys_blocks.head);
*blockptr = block;
addr = block->target_start;
+ *pfnptr = dump_paddr_to_pfn(s, addr);
} else {
- addr = dump_pfn_to_paddr(s, *pfnptr + 1);
+ *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 */
- block = QTAILQ_NEXT(block, next);
- *blockptr = block;
- 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 (!buf) {
+ if (n == page_size) {
+ /* this is a whole target page, go for it */
+ assert(addr % page_size == 0);
+ buf = hbuf;
+ break;
+ } else if (bufptr) {
+ assert(*bufptr);
+ buf = *bufptr;
+ memset(buf, 0, page_size);
+ } else {
+ return true;
+ }
+ }
+
+ memcpy(buf + addr % page_size, hbuf, n);
+ addr += n;
+ if (addr % page_size == 0) {
+ /* we filled up the 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 (buf) {
+ /* no, but we already filled something earlier, return it
*/
+ break;
+ } else {
+ /* else continue from there */
+ *pfnptr = dump_paddr_to_pfn(s, addr);
+ }
+ }
}
The loop is a bit confusing and the code is not that easy to follow.
... but I don't have a good idea to do it any better/cleaner. :)
So I assume as long as testing is good, this is fine
Acked-by: David Hildenbrand <[email protected]>
--
Thanks,
David / dhildenb
