[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH v4] EFI: always map EfiRuntimeServices{Code,Data}
Hi Jan, On 27/01/2022 12:25, Jan Beulich wrote: On 27.01.2022 11:45, Julien Grall wrote:On 12/01/2022 08:45, Jan Beulich wrote:From: Sergey Temerkhanov <s.temerkhanov@xxxxxxxxx> This helps overcome problems observed with some UEFI implementationsWould it be possible to provide some details about the platform? This is helpful to track why a workaround is present.I cannot provide any details. I took over the patch after pinging Sergey more than once, without any reaction. It was him to actually run into the problem in the wild. This is a quite unfortunate. which don't set the Attributes field in memery descriptors properly.typo: s/memery/memory/Signed-off-by: Sergey Temerkhanov <s.temerkhanov@xxxxxxxxx> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx> --- v4: Drop EFI_MEMORY_CACHEABILITY_MASK. Fold with pre-existing if() (into switch()). Style. --- I guess "map_bs" would also want honoring in efi_exit_boot(), but that's yet another patch then I suppose.IIUC, we would need to invalidate the mapping when map_bs was used. Is it correct? If so, then I agree this sounds separate to the issue you are describing here.No, the other way around: We'd also need to put in a valid virtual address there for EfiBootServices{Code,Data}. I expect this wasn't done when map_bs was introduced because iirc at that time the code fragment in efi_exit_boot() was entirely dead, present merely for documentation purposes.--- a/xen/common/efi/boot.c +++ b/xen/common/efi/boot.c @@ -1094,7 +1094,13 @@ static void __init efi_exit_boot(EFI_HAN { EFI_MEMORY_DESCRIPTOR *desc = efi_memmap + i;- if ( desc->Attribute & EFI_MEMORY_RUNTIME )+ /* + * Runtime services regions are always mapped here. + * Attributes may be adjusted in efi_init_memory(). + */ + if ( (desc->Attribute & EFI_MEMORY_RUNTIME) || + desc->Type == EfiRuntimeServicesCode || + desc->Type == EfiRuntimeServicesData )My knowledge with the stub is limited. Would you be able to explain why we need to map the runtime services even with !efi_enabled(EFI_RS)?In principle we wouldn't need to, but the final setting of this bit isn't known yet at this point - it'll be known only after parsing the command line (see parse_efi_param()). Oh. I thought efi_exit_boot() was called *after* efi_init_memory(). Your answer about 'map_bs' also make more sense. Thanks for the explanation! Reviewed-by: Julien Grall <jgrall@xxxxxxxxxx> Cheers, -- Julien Grall
|
Lists.xenproject.org is hosted with RackSpace, monitoring our |