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Message-ID: <4ed67e5b-c2ea-4dc3-b4c5-f8f112b0cd40@gmail.com> Date: Fri, 10 Jan 2025 11:12:41 +0000 From: Usama Arif <usamaarif642@...il.com> To: Dave Young <dyoung@...hat.com> Cc: linux-efi@...r.kernel.org, devel@...2.groups.io, kexec@...ts.infradead.org, ardb@...nel.org, hannes@...xchg.org, x86@...nel.org, linux-kernel@...r.kernel.org, leitao@...ian.org, gourry@...rry.net, kernel-team@...a.com Subject: Re: [RFC 2/2] efi/memattr: add efi_mem_attr_table as a reserved region in 820_table_firmware On 10/01/2025 02:50, Dave Young wrote: > Hi Usama, > > On Thu, 9 Jan 2025 at 06:00, Usama Arif <usamaarif642@...il.com> wrote: >> >> When this area is not reserved, it comes up as usable in >> /sys/firmware/memmap. This means that kexec, which uses that memmap >> to find usable memory regions, can select the region where >> efi_mem_attr_table is and overwrite it and relocate_kernel. > > Is the attr table BOOT SERVICE DATA? If so, does efi_mem_reserve() > work for you? > Just refer to esrt.c. > Hi Dave, Its a bit difficult to reproduce the problem and therefore test the fix, but we are seeing it a lot in production. Ard proposed the same thing in https://lore.kernel.org/all/6b4780a5-ada0-405e-9f0a-4d2186177f29@gmail.com/ but as I mentioned there, I dont think that efi_mem_reserve would help, as efi_mem_reserve changes e820_table, while kexec looks at /sys/firmware/memmap which uses e820_table_firmware. Thanks, Usama > Thanks > Dave >
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