[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] efi/libstub/fdt: Standardize the names of EFI stub parameters
On 2015/9/11 23:45, Daniel Kiper wrote: > On Fri, Sep 11, 2015 at 03:30:15PM +0200, Ard Biesheuvel wrote: >> On 11 September 2015 at 15:14, Stefano Stabellini >> <stefano.stabellini@xxxxxxxxxxxxx> wrote: >>> On Fri, 11 Sep 2015, Daniel Kiper wrote: >>>> On Thu, Sep 10, 2015 at 05:23:02PM +0100, Mark Rutland wrote: >>>>>>> C) When you could go: >>>>>>> >>>>>>> DT -> Discover Xen -> Xen-specific stuff -> Xen-specific EFI/ACPI >>>>>>> discovery >>>>>> >>>>>> I take you mean discovering Xen with the usual Xen hypervisor node on >>>>>> device tree. I think that C) is a good option actually. I like it. Not >>>>>> sure why we didn't think about this earlier. Is there anything EFI or >>>>>> ACPI which is needed before Xen support is discovered by >>>>>> arch/arm64/kernel/setup.c:setup_arch -> xen_early_init()? >>>>> >>>>> Currently lots (including the memory map). With the stuff to support >>>>> SPCR, the ACPI discovery would be moved before xen_early_init(). >>>>> >>>>>> If not, we could just go for this. A lot of complexity would go away. >>>>> >>>>> I suspect this would still be fairly complex, but would at least prevent >>>>> the Xen-specific EFI handling from adversely affecting the native case. >>>>> >>>>>>> D) If you want to be generic: >>>>>>> EFI -> EFI application -> EFI tables -> ACPI tables -> Xen-specific >>>>>>> stuff >>>>>>> \------------------------------------------/ >>>>>>> (virtualize these, provide shims to Dom0, but handle >>>>>>> everything in Xen itself) >>>>>> >>>>>> I think that this is good in theory but could turn out to be a lot of >>>>>> work in practice. We could probably virtualize the RuntimeServices but >>>>>> the BootServices are troublesome. >>>>> >>>>> What's troublesome with the boot services? >>>>> >>>>> What can't be simulated? >>>> >>>> How do you want to access bare metal EFI boot services from dom0 if they >>>> were shutdown long time ago before loading dom0 image? What do you need >>>> from EFI boot services in dom0? >>> >>> That's right. Trying to emulate BootServices after the real >>> ExitBootServices has already been called seems like a very bad plan. >>> >>> I think that whatever interface we come up with, would need to be past >>> ExitBootServices. >> >> It feels like this discussion is going in circles. >> >> When we discussed this six months ago, we already concluded that, >> since UEFI is the only specified way that the presence of ACPI is >> advertised on an ARM system, we need to emulate UEFI to some extent. >> >> So we need the EFI system table to expose the UEFI configuration table >> that carries the ACPI root pointer. >> >> Since ACPI support also relies on the UEFI memory map (I think?), we >> need that as well. >> >> These two items are exactly what we pass via the UEFI DT properties, >> so we should indeed promote the current de-facto binding to a proper >> binding, and renaming the properties makes sense in that context. >> >> I agree that this should also include a description of the expected >> state of the firmware, i.e., that ExitBootServices() has been called, >> and that the memory map has been populated with virtual address, which >> have been installed using SetVirtualAddressMap() if they differ from >> the physical addresses. (The current implementation on the kernel side >> is perfectly capable of dealing with a 1:1 mapping). >> >> Beyond that, there is no point in pretending to be a full UEFI >> implementation, imo. Boot services are not required, nor are runtime >> services (only the current EFI init code on arm needs to be modified >> to deal with a NULL runtime services pointer) > > Taking into account above I think that you have most of the code in place. > Please take a look at linux/arch/x86/xen/efi.c, linux/drivers/acpi/osl.c > and linux/drivers/xen/efi.c (maybe somewhere else). In general you should > create ARM version of xen_efi_init() (x86 version you can find in > linux/drivers/xen/efi.c; it is very simple thing), maybe add some > code in a few places and voila. > It only needs to apply following patch to fix a bug in Linux kernel when mapping EFI_MEMORY_RUNTIME memory. Author: Shannon Zhao <shannon.zhao@xxxxxxxxxx> Date: Thu Aug 20 14:54:58 2015 +0800 arm64/efi: Fix a bug when no EFI_MEMORY_RUNTIME memory found Currently if the attribute type of all the EFI Memory Descriptors are not EFI_MEMORY_RUNTIME, efi_virtmap_init will return true. But at this case, it expect false as there are no EFI memory for RUNTIME. Fix it by introducing a status to show whether it finds EFI_MEMORY_RUNTIME. Signed-off-by: Shannon Zhao <shannon.zhao@xxxxxxxxxx> diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c index e8ca6ea..bad7f87 100644 --- a/arch/arm64/kernel/efi.c +++ b/arch/arm64/kernel/efi.c @@ -233,6 +233,7 @@ void __init efi_init(void) static bool __init efi_virtmap_init(void) { efi_memory_desc_t *md; + bool status = false; for_each_efi_memory_desc(&memmap, md) { u64 paddr, npages, size; @@ -264,8 +265,11 @@ static bool __init efi_virtmap_init(void) prot = PAGE_KERNEL; create_pgd_mapping(&efi_mm, paddr, md->virt_addr, size, prot); + status = true; } - return true; + if (status) + return true; + return false; } -- Shannon _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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