Re: [PATCH] x86/boot: Use EFI setup data if provided

[Dave Young]

On 03/25/19 at 06:47am, Junichi Nomura wrote:
> On 3/25/19 3:19 PM, Dave Young wrote:
> > On 03/25/19 at 02:01pm, Dave Young wrote:
> >> On 03/25/19 at 12:27am, Junichi Nomura wrote:
> >>> On Fri, Mar 22, 2019 at 04:23:28PM +0100, Borislav Petkov wrote:
> >>>> On Fri, Mar 22, 2019 at 11:03:43AM +0000, Junichi Nomura wrote:
> >>>>> Commit 3a63f70bf4c3a ("x86/boot: Early parse RSDP and save it in
> >>>>> boot_params") broke kexec boot on EFI systems.  efi_get_rsdp_addr()
> >>>>> in the early parsing code tries to search RSDP from EFI table but
> >>>>> whose address is virtual.
> >>>>>
> >>>>> Since kexec(1) provides physical address of config_table via boot_params,
> >>>>> efi_get_rsdp_addr() should look for setup_data in the same way as
> >>>>> efi_systab_init() in arch/x86/platform/efi/efi.c does.
> >>>>
> >>>> If the kexec kernel should continue to use efi_systab_init() then you
> >>>> should make efi_get_rsdp_addr() exit early in the kexec-ed kernel.
> >>>
> >>> I'm not sure which way kexec devel is going. Added kexec list.
> >>> Here is the version that exits early in efi_get_rsdp_addr().
> >>>
> >>> [PATCH] x86/boot: Don't try to search RSDP from EFI when kexec-booted
> >>>
> >>> Commit 3a63f70bf4c3a ("x86/boot: Early parse RSDP and save it in
> >>> boot_params") broke kexec boot on EFI systems.  efi_get_rsdp_addr()
> >>> in the early parsing code tries to search RSDP from EFI table but
> >>> whose address is virtual.
> >>>
> >>> Normally kexec(1) provides physical address of config_table via boot_params
> >>> and EFI code uses that during initialization.
> >>> For the early boot code, we just exit efi_get_rsdp_addr() early if the kernel
> >>> is booted by kexec.
> >>>
> >>> Fixes: 3a63f70bf4c3a ("x86/boot: Early parse RSDP and save it in boot_params")
> >>> Signed-off-by: Jun'ichi Nomura <j-nomura@xxxxxxxxxxxxx>
> >>> Cc: Chao Fan <fanc.fnst@xxxxxxxxxxxxxx>
> >>> Cc: Borislav Petkov <bp@xxxxxxx>
> >>>
> >>> diff --git a/arch/x86/boot/compressed/acpi.c b/arch/x86/boot/compressed/acpi.c
> >>> index 0ef4ad5..1cefc43 100644
> >>> --- a/arch/x86/boot/compressed/acpi.c
> >>> +++ b/arch/x86/boot/compressed/acpi.c
> >>> @@ -44,6 +44,24 @@ static acpi_physical_address get_acpi_rsdp(void)
> >>>  	return addr;
> >>>  }
> >>>  
> >>> +static bool is_kexec_booted(void)
> >>> +{
> >>> +	struct setup_data *data;
> >>> +
> >>> +	/*
> >>> +	 * kexec-tools provides EFI setup data so that kexec-ed kernel
> >>> +	 * can find proper tables.
> >>> +	 */
> >>> +	data = (struct setup_data *) boot_params->hdr.setup_data;
> >>> +	while (data) {
> >>> +		if (data->type == SETUP_EFI)
> >>> +			return true;
> >>> +		data = (struct setup_data *) data->next;
> >>> +	}
> >>> +
> >>> +	return false;
> >>> +}
> >>> +
> >>>  /* Search EFI system tables for RSDP. */
> >>>  static acpi_physical_address efi_get_rsdp_addr(void)
> >>>  {
> >>> @@ -57,6 +75,10 @@ static acpi_physical_address efi_get_rsdp_addr(void)
> >>>  	int size, i;
> >>>  	char *sig;
> >>>  
> >>> +	/* If the system is kexec-booted, poking EFI systab may not work. */
> >>> +	if (is_kexec_booted())
> >>> +		return 0;
> >>> +
> >>>  	ei = &boot_params->efi_info;
> >>>  	sig = (char *)&ei->efi_loader_signature;
> >>>  
> >>>
> >>> _______________________________________________
> >>> kexec mailing list
> >>> kexec@xxxxxxxxxxxxxxxxxxx
> >>> http://lists.infradead.org/mailman/listinfo/kexec
> >>
> >> Good catch, this way looks good to me.  But the function
> >> is_kexec_booted can be compiled when #ifdef CONFIG_EFI
> >>
> >> Otherwise:
> >>
> >> Acked-by: Dave Young <dyoung@xxxxxxxxxx>
> >>
> > 
> > Hold on, I replied too quick.  One question is does the above patch
> > passed your test?   It can workaround and skip the wrong phys addr
> > issue, but the acpi early parsing still fails because efi_get_rsdp_addr
> > return 0? 
> 
> The patch works for me.
> Early parsing fails with the 2nd patch but it boots fine.
> EFI initialization is done later without boot_params->acpi_rsdp_addr.
> I think that's how v5.0 and earlier kernels work.

Ok, thanks 

> 
> > If this is the case you may need go with your old patch.
> > 
> > I think normally people do not see this bug, because kernel will set the
> > rsdp in boot_params->acpi_rsdp_addr.  Maybe you are testing with
> 
> I think it's only done for file-based kexec interface.

Saw Kairui's another reply, yes, kexec-tools need a patch to fill the
value as well then.

I would vote for a repost of your old patch with some #ifdef

Thanks
Dave