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

[Dave Young]

On 11/26/13 at 10:04pm, Matt Fleming wrote:
> On Tue, 26 Nov, at 01:57:52PM, 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, 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@xxxxxxxxxx>
> > ---
> >  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(-)
> 
> [...]
> 
> > +void __init parse_efi_setup(u64 phys_addr, u32 data_len)
> > +{
> > +	int size;
> > +	struct setup_data *sdata;
> > +	u64 esdata_phys;
> > +
> > +	if (!efi_enabled(EFI_64BIT)) {
> > +		pr_warn("skipping setup_data on EFI 32BIT!");
> > +		return;
> > +	}
> 
> Hmm... this warning could be more informative. Perhaps something along
> the lines of,
> 
> 	"SETUP_EFI not supported on 32-bit\n"

Will do

> 
> because the reason we skip is because it isn't supported.
> 
> > +
> > +	sdata = early_memremap(phys_addr, data_len);
> > +	if (!sdata)
> > +		return;
> > +
> > +	size = data_len - sizeof(struct setup_data);
> > +
> > +	esdata_phys = phys_addr + sizeof(struct setup_data);
> > +
> > +	nr_efi_runtime_map = (size - sizeof(struct efi_setup_data)) /
> > +			sizeof(efi_memory_desc_t);
> > +	early_iounmap(sdata, data_len);
> > +
> > +	/* iounmap esdata in function efi_enter_virtual_mode */
> > +	esdata = early_memremap(esdata_phys, size);
> > +}
> >  
> >  static efi_status_t virt_efi_get_time(efi_time_t *tm, efi_time_cap_t *tc)
> >  {
> > @@ -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)
> 
> Could we name this something more explicit? 'efi_setup' perhaps?

Sure, just efi_setup_data is a bit long, will use efi_setup in next version.

> 
> > @@ -631,6 +670,41 @@ static int __init efi_memmap_init(void)
> >  	return 0;
> >  }
> >  
> > +static int __init efi_reuse_config(u64 tables, int nr_tables)
> > +{
> > +	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.
> > +		*/
> 
> This isn't the correct multi-line comment format,

Will update

> 
> 		/*
> 		 * This is the preferred way to to write a multi-line
> 		 * comment.
> 		 */
> 
> > +		if (!efi_guidcmp(guid, SMBIOS_TABLE_GUID))
> > +			((efi_config_table_64_t *)p)->table = esdata->smbios;
> > +		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);
> > +
> 
> Would it make sense to move the ->smbios check inside efi_reuse_config()
> in case we need to extend the number of tables in the future?

Good suggestion, will do.

> 
> >  	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.
> > + */
> > +static void __init efi_map_regions_fixed(void)
> > +{
> > +	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);
> > +	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;
> 
> Heh, I read that as 'esdata->map + 1' the first few times.

To make it more readable, I will change them like below:

p = efi_runtime_map;
md = efi_setup->map;
for (i = 0; i < nr_efi_runtime_map; i++) {
	[...]
	md += 1;
}

> 
> > +		efi_map_region_fixed(md);
> > +		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;
> > +		}
> > +		if (efi_runtime_map) {
> > +			memcpy(p, md, memmap.desc_size);
> > +			p += memmap.desc_size;
> > +		}
> 
> Is this if () needed? Is it possible to enter the loop and have
> 'efi_runtime_map' be NULL?

Yes, it is needed. if efi_runtime_map kmalloc fails I only print error, do not
return so kernel can still boot, just kexec on efi will not work that has been
put in the error message.

> 
> > +	}
> > +}
> > +
> > +/*
> >   * 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
> > + * be passed in via setup_data. In that case runtime ranges will be mapped
> > + * to fixed virtual addresses exactly same as the ones in previous kernel.
> >   */
> >  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;
> > +		}
> >  	}
> >  
> >  	BUG_ON(!efi.systab);
> > @@ -932,11 +1053,17 @@ void __init efi_enter_virtual_mode(void)
> >  	efi_setup_page_tables();
> >  	efi_sync_low_kernel_mappings();
> >  
> > -	status = phys_efi_set_virtual_address_map(
> > -		memmap.desc_size * count,
> > -		memmap.desc_size,
> > -		memmap.desc_version,
> > -		(efi_memory_desc_t *)__pa(new_memmap));
> > +	if (esdata) {
> > +		status = EFI_SUCCESS;
> > +		early_iounmap(esdata, sizeof(struct efi_setup_data) +
> > +			      nr_efi_runtime_map *
> > +			      sizeof(efi_memory_desc_t));
> > +	} else
> > +		status = phys_efi_set_virtual_address_map(
> > +			memmap.desc_size * count,
> > +			memmap.desc_size,
> > +			memmap.desc_version,
> > +			(efi_memory_desc_t *)__pa(new_memmap));
> >  
> >  	if (status != EFI_SUCCESS) {
> >  		pr_alert("Unable to switch EFI into virtual mode "
> 
> Please fold the pr_alert() into the else branch so that you don't have
> to do the 'status = EFI_SUCCESS' dance.

Good suggestion, will do.

Thanks for review
Dave
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