On 12.07.2022 01:14, Demi Marie Obenour wrote: > The EFI System Resource Table (ESRT) is necessary for fwupd to identify > firmware updates to install. According to the UEFI specification ยง23.4, > the ESRT shall be stored in memory of type EfiBootServicesData. However, > memory of type EfiBootServicesData is considered general-purpose memory > by Xen, so the ESRT needs to be moved somewhere where Xen will not > overwrite it. Copy the ESRT to memory of type EfiRuntimeServicesData, > which Xen will not reuse. dom0 can use the ESRT if (and only if) it is > in memory of type EfiRuntimeServicesData. > > Earlier versions of this patch reserved the memory in which the ESRT was > located. This created awkward alignment problems, and required either > splitting the E820 table or wasting memory. It also would have required > a new platform op for dom0 to use to indicate if the ESRT is reserved. > By copying the ESRT into EfiRuntimeServicesData memory, the E820 table > does not need to be modified, and dom0 can just check the type of the > memory region containing the ESRT. The copy is only done if the ESRT is > not already in EfiRuntimeServicesData memory, avoiding memory leaks on > repeated kexec. > > See https://lore.kernel.org/xen-devel/20200818184018.GN1679@mail-itl/T/ > for details. > > Signed-off-by: Demi Marie Obenour <[email protected]> > Tested-by: Luca Fancellu <[email protected]>
Reviewed-by: Jan Beulich <[email protected]>
