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SubjectRe: [PATCH v2 2/2] x86, kexec_file_load: make it work with efi=noruntime or efi=old_map
On 01/16/19 at 12:10am, Borislav Petkov wrote:
> On Tue, Jan 15, 2019 at 05:58:34PM +0800, Kairui Song wrote:
> > When efi=noruntime or efi=oldmap is used, EFI services won't be available
> > in the second kernel, therefore the second kernel will not be able to get
> > the ACPI RSDP address from firmware by calling EFI services and won't
> > boot. Previously we are expecting the user to set the acpi_rsdp=<addr>
> > on kernel command line for second kernel as there was no way to pass RSDP
> > address to second kernel.
> >
> > After commit e6e094e053af ('x86/acpi, x86/boot: Take RSDP address from
> > boot params if available'), now it's possible to set an acpi_rsdp_addr
> > parameter in the boot_params passed to second kernel, this commit make
> > use of it, detect and set the RSDP address when it's required for second
> > kernel to boot.
> >
> > Tested with an EFI enabled KVM VM with efi=noruntime.
> >
> > Suggested-by: Dave Young <dyoung@redhat.com>
> > Signed-off-by: Kairui Song <kasong@redhat.com>
> > ---
> > arch/x86/kernel/kexec-bzimage64.c | 21 +++++++++++++++++++++
> > drivers/acpi/acpica/tbxfroot.c | 3 +--
> > include/acpi/acpixf.h | 2 +-
> > 3 files changed, 23 insertions(+), 3 deletions(-)
> >
> > diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c
> > index 53917a3ebf94..0a90dcbd041f 100644
> > --- a/arch/x86/kernel/kexec-bzimage64.c
> > +++ b/arch/x86/kernel/kexec-bzimage64.c
> > @@ -20,6 +20,7 @@
> > #include <linux/mm.h>
> > #include <linux/efi.h>
> > #include <linux/verification.h>
> > +#include <linux/acpi.h>
> >
> > #include <asm/bootparam.h>
> > #include <asm/setup.h>
> > @@ -255,8 +256,28 @@ setup_boot_parameters(struct kimage *image, struct boot_params *params,
> > /* Setup EFI state */
> > setup_efi_state(params, params_load_addr, efi_map_offset, efi_map_sz,
> > efi_setup_data_offset);
> > +
> > +#ifdef CONFIG_ACPI
> > + /* Setup ACPI RSDP pointer in case EFI is not available in second kernel */
> > + if (!acpi_disabled && (!efi_enabled(EFI_RUNTIME_SERVICES) || efi_enabled(EFI_OLD_MEMMAP))) {
> > + /* Copied from acpi_os_get_root_pointer accordingly */
> > + params->acpi_rsdp_addr = boot_params.acpi_rsdp_addr;
> > + if (!params->acpi_rsdp_addr) {
> > + if (efi_enabled(EFI_CONFIG_TABLES)) {
> > + if (efi.acpi20 != EFI_INVALID_TABLE_ADDR)
> > + params->acpi_rsdp_addr = efi.acpi20;
> > + else if (efi.acpi != EFI_INVALID_TABLE_ADDR)
> > + params->acpi_rsdp_addr = efi.acpi;
> > + } else if (IS_ENABLED(CONFIG_ACPI_LEGACY_TABLES_LOOKUP)) {
> > + acpi_find_root_pointer(&params->acpi_rsdp_addr);
> > + }
> > + }
> > + if (!params->acpi_rsdp_addr)
> > + pr_warn("RSDP is not available for second kernel\n");
> > + }
> > #endif
>
> Amazing the amount of ACPI RDSP parsing and fiddling patches flying
> around these days...
>
> In any case, this needs to be synchronized with:
>
> https://lkml.kernel.org/r/20190107032243.25324-1-fanc.fnst@cn.fujitsu.com
>
> and checked whether the above can be used instead of sprinkling of ACPI
> parsing code left and right.

Both Baoquan and Chao are cced for comments.
The above KASLR patches seems some early code to parsing acpi, but I think in this
patch just call acpi function to get the root pointer no need to add the
duplicate logic of if/else/else if.

Kairui, do you have any reason for the checking? Is there some simple
acpi function to just return the root pointer?

>
> Thx.
>
> --
> Regards/Gruss,
> Boris.
>
> Good mailing practices for 400: avoid top-posting and trim the reply.

Thanks
Dave

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