Re: [PATCH v7 09/12] efi: passing kexec necessary efi data via setup_data

Matt Fleming
2013-12-21T14:54:15Z

On Fri, 20 Dec, at 06:02:19PM, Dave Young wrote:
> Add a new setup_data type SETUP_EFI for kexec use.
> Passing the saved fw_vendor, runtime, config tables and efi runtime mappings.
>
> When entering virtual mode, directly mapping the efi runtime ragions which
> we passed in previously. And skip the step to call SetVirtualAddressMap.
>
> Specially for HP z420 workstation we need save the smbios physical address.
> The kernel boot sequence proceeds in the following order. Step 2
> requires efi.smbios to be the physical address. However, I found that on
> HP z420 EFI system table has a virtual address of SMBIOS in step 1. Hence,
> we need set it back to the physical address with the smbios in
> efi_setup_data. (When it is still the physical address, it simply sets
> the same value.)
>
> 1. efi_init() - Set efi.smbios from EFI system table
> 2. dmi_scan_machine() - Temporary map efi.smbios to access SMBIOS table
> 3. efi_enter_virtual_mode() - Map EFI ranges
>
> Tested on ovmf+qemu, lenovo thinkpad, a dell laptop and an
> HP z420 workstation.
>
> v2: refresh based on previous patch changes, code cleanup.
> v3: use ioremap instead of phys_to_virt for efi_setup
> v5: improve some code structure per comments from Matt
> Boris: improve code structure, spell fix, etc.
> Improve changelog from Toshi.
> change the variable efi_setup to the physical address of efi setup_data
> instead of the ioremapped virt address
> v6: Boris: Documentation fixes
> move parse_efi_setup to efi_$(BITS).c
> simplify parse_efi_setup logic
> Matt: check return value of efi_reuse_config
> v7: cleanup efi_map_regions and efi_map_regions_fixed
> remove useless return at the end of efi_enter_virtual_mode
>
> Signed-off-by: Dave Young <dyoung@redhat.com>
> ---
> arch/x86/include/asm/efi.h | 13 +++
> arch/x86/include/uapi/asm/bootparam.h | 1 +
> arch/x86/kernel/setup.c | 3 +
> arch/x86/platform/efi/efi.c | 159 ++++++++++++++++++++++++++++------
> arch/x86/platform/efi/efi_32.c | 1 +
> arch/x86/platform/efi/efi_64.c | 6 ++
> 6 files changed, 158 insertions(+), 25 deletions(-)

[...]

> efi_systab.hdr = systab64->hdr;
> - efi_systab.fw_vendor = systab64->fw_vendor;
> - tmp |= systab64->fw_vendor;
> +
> + efi_systab.fw_vendor = data ? (unsigned long)data->fw_vendor :
> + systab64->fw_vendor;
> + tmp |= efi_systab.fw_vendor;

[... snip ...]

> @@ -519,15 +530,20 @@ static int __init efi_systab_init(void *phys)
> tmp |= systab64->stderr_handle;
> efi_systab.stderr = systab64->stderr;
> tmp |= systab64->stderr;
> - efi_systab.runtime = (void *)(unsigned long)systab64->runtime;
> - tmp |= systab64->runtime;
> + efi_systab.runtime = data ?
> + (void *)(unsigned long)data->runtime :
> + (void *)(unsigned long)systab64->runtime;
> + tmp |= (unsigned long)efi_systab.runtime;
> efi_systab.boottime = (void *)(unsigned long)systab64->boottime;
> tmp |= systab64->boottime;
> efi_systab.nr_tables = systab64->nr_tables;
> - efi_systab.tables = systab64->tables;
> - tmp |= systab64->tables;
> + efi_systab.tables = data ? (unsigned long)data->tables :
> + systab64->tables;
> + tmp |= efi_systab.tables;
>
> early_memunmap(systab64, sizeof(*systab64));
> + if (data)
> + early_memunmap(data, sizeof(*data));
> #ifdef CONFIG_X86_32
> if (tmp >> 32) {
> pr_err("EFI data located above 4GB, disabling EFI.\n");

This isn't correct, and means we now won't trigger this pr_err() if
booting a CONFIG_X86_32 kernel with EFI_64BIT and where the ->fw_vendor,
->runtime or ->tables pointer is above 4GB - you've mixed up systab and
systab64. I've fixed this up like so when applying this patch,

---

@@ -494,18 +495,27 @@ static int __init efi_systab_init(void *phys)
{
if (efi_enabled(EFI_64BIT)) {
efi_system_table_64_t *systab64;
+ struct efi_setup_data *data = NULL;
u64 tmp = 0;

+ if (efi_setup) {
+ data = early_memremap(efi_setup, sizeof(*data));
+ if (!data)
+ return -ENOMEM;
+ }
systab64 = early_ioremap((unsigned long)phys,
sizeof(*systab64));
if (systab64 == NULL) {
pr_err("Couldn't map the system table!\n");
+ if (data)
+ early_iounmap(data, sizeof(*data));
return -ENOMEM;
}

efi_systab.hdr = systab64->hdr;
- efi_systab.fw_vendor = systab64->fw_vendor;
- tmp |= systab64->fw_vendor;
+ efi_systab.fw_vendor = data ? (unsigned long)data->fw_vendor :
+ systab64->fw_vendor;
+ tmp |= data ? data->fw_vendor : systab64->fw_vendor;
efi_systab.fw_revision = systab64->fw_revision;
efi_systab.con_in_handle = systab64->con_in_handle;
tmp |= systab64->con_in_handle;
@@ -519,15 +529,20 @@ static int __init efi_systab_init(void *phys)
tmp |= systab64->stderr_handle;
efi_systab.stderr = systab64->stderr;
tmp |= systab64->stderr;
- efi_systab.runtime = (void *)(unsigned long)systab64->runtime;
- tmp |= systab64->runtime;
+ efi_systab.runtime = data ?
+ (void *)(unsigned long)data->runtime :
+ (void *)(unsigned long)systab64->runtime;
+ tmp |= data ? data->runtime : systab64->runtime;
efi_systab.boottime = (void *)(unsigned long)systab64->boottime;
tmp |= systab64->boottime;
efi_systab.nr_tables = systab64->nr_tables;
- efi_systab.tables = systab64->tables;
- tmp |= systab64->tables;
+ efi_systab.tables = data ? (unsigned long)data->tables :
+ systab64->tables;
+ tmp |= data ? data->tables : systab64->tables;

early_iounmap(systab64, sizeof(*systab64));
+ if (data)
+ early_iounmap(data, sizeof(*data));
#ifdef CONFIG_X86_32
if (tmp >> 32) {
pr_err("EFI data located above 4GB, disabling EFI.\n");

--
Matt Fleming, Intel Open Source Technology Center