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Option memmap=$ removes RAM from the E820 >> map while its bits are still set in the bitmap. >> >> The removed range, such as a memmap=...$... hole, is then still treated as >> unaccepted RAM and accept_memory() tries to accept it. The hole is not >> mapped, so on SEV-SNP the PVALIDATE faults and the guest crashes early in >> the boot: >> >> BUG: unable to handle page fault for address: ffff8a14bfe00000 >> RIP: 0010:pvalidate_pages+0xc0/0x250 >> set_pages_state+0x41a/0x440 >> snp_accept_memory+0x3e/0x50 >> accept_memory+0x186/0x260 >> __free_pages_core+0xd2/0x240 >> memblock_free_pages+0x1b/0x30 >> memblock_free_all+0x275/0x2d0 >> >> This was seen with memmap=2M$0x1ffe00000, a 2 MiB hole in RAM, on a 19 GiB >> SNP guest with lazy acceptance. >> >> Fixes: 2053bc57f367 ("efi: Add unaccepted memory support") >> Signed-off-by: Pankaj Gupta >> --- >> arch/x86/include/asm/unaccepted_memory.h | 23 ++++++++++++++++++++++- >> 1 file changed, 22 insertions(+), 1 deletion(-) >> > Can we just disallow memmap= when running in a confidential VM? My experiments showed: memmap itself don't have a problem but memap with a hole is causing crash. There might be some usecases which are already using this, e.g: https://lore.kernel.org/all/20261029-cma-multi-v1-0-2cbced8b5cb7@kernel.org/ Thanks, Pankaj >