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Peter Anvin" , "Tom Lendacky" , "Kiryl Shutsemau (Meta)" , linux-kernel@vger.kernel.org, "Mike Rapoport" , linux-mm@kvack.org Message-Id: In-Reply-To: <20261102113127.161823-1-pankaj.gupta@amd.com> References: <20261102113127.161823-1-pankaj.gupta@amd.com> Subject: Re: [PATCH] x86/unaccepted_memory: Do not accept ranges that are no longer E820 RAM Content-Type: text/plain Content-Transfer-Encoding: 7bit Hello Pankaj, On Mon, 2 Nov 2026, at 12:31, Pankaj Gupta wrote: > The EFI stub builds the unaccepted memory bitmap before the kernel parses > its command line. 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?