Re: [PATCH v4 07/12] efi: passing kexec necessary efi data via setup_data

Dave Young
2013-11-29T09:14:16Z

On 11/27/13 at 03:07pm, Borislav Petkov wrote:
> On Tue, Nov 26, 2013 at 01:57:52PM +0800, 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 it need another variable
> > saving,
>
> Why the special handling? Does that mean, this is going to be the case
> for other HP UEFI implementations too?

I have only one HP machine for testing, Maybe Toshi can help to verify
on other machines. Just comment out the function efi_reuse_config to see
if kexec kernel panic.

>
> > it's the smbios physical address, the HP bios
> > also update the SMBIOS address after entering virtual mode
> > besides of the standard fw_vendor,runtime and config table.
> >
> > 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 esdata
> >
> > Signed-off-by: Dave Young <dyoung@redhat.com>
> > ---
> > arch/x86/include/asm/efi.h | 12 +++
> > arch/x86/include/uapi/asm/bootparam.h | 1 +
> > arch/x86/kernel/setup.c | 3 +
> > arch/x86/platform/efi/efi.c | 161 ++++++++++++++++++++++++++++++----
> > 4 files changed, 160 insertions(+), 17 deletions(-)
> >
> > diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
> > index 9fbaeb2..73d5643 100644
> > --- a/arch/x86/include/asm/efi.h
> > +++ b/arch/x86/include/asm/efi.h
> > @@ -133,6 +133,18 @@ extern void efi_sync_low_kernel_mappings(void);
> > extern void efi_setup_page_tables(void);
> > extern void __init old_map_region(efi_memory_desc_t *md);
> >
> > +struct efi_setup_data {
> > + u64 fw_vendor;
> > + u64 runtime;
> > + u64 tables;
> > + u64 smbios;
> > + u64 reserved[8];
>
> What's that for?

That's reserved for future extension use, who knows if we will need
to pass other fields in the future.

>
> > + efi_memory_desc_t map[0];
> > +};
> > +
> > +extern void parse_efi_setup(u64 phys_addr, u32 data_len);
> > +extern struct efi_setup_data *esdata;
> > +
> > #ifdef CONFIG_EFI
> >
> > static inline bool efi_is_native(void)
>
> [ … ]
>
> > diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
> > index c3a2aaa..fafeb40 100644
> > --- a/arch/x86/platform/efi/efi.c
> > +++ b/arch/x86/platform/efi/efi.c
> > @@ -504,8 +531,12 @@ static int __init efi_systab_init(void *phys)
> > }
> >
> > efi_systab.hdr = systab64->hdr;
> > - efi_systab.fw_vendor = systab64->fw_vendor;
> > - tmp |= systab64->fw_vendor;
> > +
> > + if (esdata)
> > + efi_systab.fw_vendor = (unsigned long)esdata->fw_vendor;
> > + else
> > + efi_systab.fw_vendor = systab64->fw_vendor;
>
> efi_systab.fw_vendor = esdata ? (unsigned long)esdata->fw_vendor
> : systab64->fw_vendor;

Ok, will update.

>
> > + tmp |= efi_systab.fw_vendor;
> > efi_systab.fw_revision = systab64->fw_revision;
> > efi_systab.con_in_handle = systab64->con_in_handle;
> > tmp |= systab64->con_in_handle;
> > @@ -519,13 +550,21 @@ 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;
> > + if (esdata)
> > + efi_systab.runtime =
> > + (void *)(unsigned long)esdata->runtime;
> > + else
> > + efi_systab.runtime =
> > + (void *)(unsigned long)systab64->runtime;
>
> Ditto. Which would take care of these linebreaks which are ugly.

Will do.

>
> > + 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;
> > + if (esdata)
> > + efi_systab.tables = (unsigned long)esdata->tables;
> > + else
> > + efi_systab.tables = systab64->tables;
>
> Ditto.

Will do

>
> > + tmp |= efi_systab.tables;
> >
> > early_iounmap(systab64, sizeof(*systab64));
> > #ifdef CONFIG_X86_32
> > @@ -631,6 +670,41 @@ static int __init efi_memmap_init(void)
> > return 0;
> > }
> >
> > +static int __init efi_reuse_config(u64 tables, int nr_tables)
>
> Static function - no need for "efi_" prefix.

Ok. I'm not very satisfied with the function name, any better
suggestion?

reuse_config
use_old_config_phys_addr
update_config_entry_with_phys_addr
...

>
> > +{
> > + void *p, *tablep;
> > + int i, sz;
> > +
> > + if (!efi_enabled(EFI_64BIT))
> > + return 0;
> > +
> > + sz = sizeof(efi_config_table_64_t);
> > +
> > + p = tablep = early_memremap(tables, nr_tables * sz);
> > + if (!p) {
> > + pr_err("Could not map Configuration table!\n");
> > + return -ENOMEM;
> > + }
> > +
> > + for (i = 0; i < efi.systab->nr_tables; i++) {
> > + efi_guid_t guid;
> > +
> > + guid = ((efi_config_table_64_t *)p)->guid;
> > +
> > + /*
> > + HP z420 workstation smbios will be convert to
> > + virtual address after enter virtual mode.
> > + Thus in case kexec/kdump the physical address
> > + will be passed in setup_data.
>
> Is that what the commit message above says? I'm having a hard time
> parsing this text.

Since Matt suggest to extend the function for other possible field
other than smbios, so I would like to move comment to the front
of the function like below:
/*
* For kexec kernel there's some special config table entries which will be
* converted to virtual addresses after entering virtual mode. In kexec kernel
* we need the physical addresses instead, thus passing them via setup_data
* and update the entries to physical addresses in this function.
*
* Currently only handles smbios which is necessary for HP z420.
*/
static int __init efi_reuse_config(u64 tables, int nr_tables)

>
> > + */
> > + if (!efi_guidcmp(guid, SMBIOS_TABLE_GUID))
> > + ((efi_config_table_64_t *)p)->table = esdata->smbios;
>
> ...and yet we do this for *every* UEFI box. Why not HP only?

Is there any idea in your mind how to add the code for HP only?

>
> > + p += sz;
> > + }
> > + early_iounmap(tablep, nr_tables * sz);
> > + return 0;
> > +}
> > +
> > void __init efi_init(void)
> > {
> > efi_char16_t *c16;
> > @@ -676,6 +750,9 @@ void __init efi_init(void)
> > efi.systab->hdr.revision >> 16,
> > efi.systab->hdr.revision & 0xffff, vendor);
> >
> > + if (esdata && esdata->smbios)
> > + efi_reuse_config(efi.systab->tables, efi.systab->nr_tables);
> > +
> > if (efi_config_init(arch_tables))
> > return;
> >
> > @@ -886,6 +963,43 @@ ret:
> > }
> >
> > /*
> > + * map efi regions which was passed via setup_data
> > + * the virt_addr is a fixed addr which was used in
> > + * 1st kernel of kexec boot.
> > + */
>
> Comment to 80 cols pls.

Will do

>
> > +static void __init efi_map_regions_fixed(void)
>
> Also no need for "efi_" prefix here.

Ok.

>
> > +{
> > + int i;
> > + unsigned long size;
> > + efi_memory_desc_t *md;
> > + u64 end, systab;
> > + void *p;
> > +
> > + efi_runtime_map = kzalloc(nr_efi_runtime_map * memmap.desc_size,
> > + GFP_KERNEL);
>
> Arg alignment.

Will do.

>
> > + if (!efi_runtime_map)
> > + pr_err("Out of memory, EFI runtime on nested kexec non-functional!\n");
> > +
> > + for (i = 0, p = efi_runtime_map; i < nr_efi_runtime_map; i++) {
> > + md = esdata->map + i;
> > + efi_map_region_fixed(md);
>
> Gaah, this function should probably have a retval which signalizes
> success/failure. For that I should probably teach __map_region to do
> that too. On the TODO list.

Yes, __map_region return an error code will be better. Will you send a
patch for __map_region? or I can add one more patch along with next version.

>
> > + size = md->num_pages << PAGE_SHIFT;
> > + end = md->phys_addr + size;
> > +
> > + systab = (u64) (unsigned long) efi_phys.systab;
> > + if (md->phys_addr <= systab && systab < end) {
> > + systab += md->virt_addr - md->phys_addr;
> > + efi.systab =
> > + (efi_system_table_t *) (unsigned long) systab;
>
> CHECK: No space is necessary after a cast
> #219: FILE: arch/x86/platform/efi/efi.c:993:

Will fix

> + efi.systab =
> + (efi_system_table_t *) (unsigned long) systab;
>
>
> And also, those broken lines are ugly. Just let it stick out over 80 cols.

Sure.

>
> > + }
> > + if (efi_runtime_map) {
> > + memcpy(p, md, memmap.desc_size);
> > + p += memmap.desc_size;
> > + }
> > + }
> > +}
> > +
> > +/*
> > * This function will switch the EFI runtime services to virtual mode.
> > * Essentially, we look through the EFI memmap and map every region that
> > * has the runtime attribute bit set in its memory descriptor into the
> > @@ -901,6 +1015,10 @@ ret:
> > * so that we're in a different address space when calling a runtime
> > * function. For function arguments passing we do copy the PGDs of the
> > * kernel page table into ->trampoline_pgd prior to each call.
> > + *
> > + * Specially for kexec boot efi runtime maps in previous kernel should
>
> boot, ...

Will update.

>
> > + * be passed in via setup_data. In that case runtime ranges will be mapped
>
> case, ...
>
> > + * to fixed virtual addresses exactly same as the ones in previous kernel.
>
> "... to the same virtual addresses as the first kernel."

Will do.

>
> > */
> > void __init efi_enter_virtual_mode(void)
> > {
> > @@ -919,12 +1037,15 @@ void __init efi_enter_virtual_mode(void)
> > return;
> > }
> >
> > - efi_merge_regions();
> > -
> > - new_memmap = efi_map_regions(&count);
> > - if (!new_memmap) {
> > - pr_err("Error reallocating memory, EFI runtime non-functional!\n");
> > - return;
> > + if (esdata)
> > + efi_map_regions_fixed();
> > + else {
> > + efi_merge_regions();
> > + new_memmap = efi_map_regions(&count);
> > + if (!new_memmap) {
> > + pr_err("Error reallocating memory, EFI runtime non-functional!\n");
> > + return;
> > + }
>
> CHECK: braces {} should be used on all arms of this statement
> #253: FILE: arch/x86/platform/efi/efi.c:1040:

Ok.

> + if (esdata)
> [...]
> + else {
> [...]
>

Thanks for carefully review
Dave

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