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From: Borislav Petkov <bp@alien8.de>
To: Baoquan He <bhe@redhat.com>
Cc: j-nomura@ce.jp.nec.com, kasong@redhat.com, dyoung@redhat.com,
	linux-kernel@vger.kernel.org, tglx@linutronix.de,
	fanc.fnst@cn.fujitsu.com, x86@kernel.org,
	kexec@lists.infradead.org, hpa@zytor.com
Subject: Re: [PATCH v5 1/2] x86/kexec: Build identity mapping for EFI systab and ACPI tables
Date: Sat, 27 Apr 2019 18:11:21 +0200	[thread overview]
Message-ID: <20190427161121.GC12360@zn.tnic> (raw)
In-Reply-To: <20190424092944.30481-2-bhe@redhat.com>

On Wed, Apr 24, 2019 at 05:29:43PM +0800, Baoquan He wrote:
> From: Kairui Song <kasong@redhat.com>
> 
> The current code only builds identity mapping for physical memory during
> kexec-type loading. The regions reserved by firmware are not covered.
> In the next patch, the boot decompressing code of kexec-ed kernel tries

There's no guarantee that when this patch gets applied, the next patch
will be the one you mean. So explain what you mean here instead.

> to access EFI systab and ACPI tables, lacking identity mapping for them
> will cause error and reset system to firmware.
> 
> This error doesn't happen on all systems. Because kexec enables gbpages
> to build identity mapping, the EFI systab and ACPI tables could have been
> covered if they share the same 1 GB area with physical memory. To make
> sure, we should map them always.
> 
> So here add mapping for them.
> 
> Signed-off-by: Kairui Song <kasong@redhat.com>

When you send someone else's patch, you need to add your SOB. Lemme
point you to

  Documentation/process/submitting-patches.rst

again. Please have a deeper look.

> ---
>  arch/x86/kernel/machine_kexec_64.c | 86 ++++++++++++++++++++++++++++++
>  1 file changed, 86 insertions(+)
> 
> diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
> index ceba408ea982..77b40c3e28d7 100644
> --- a/arch/x86/kernel/machine_kexec_64.c
> +++ b/arch/x86/kernel/machine_kexec_64.c
> @@ -18,6 +18,7 @@
>  #include <linux/io.h>
>  #include <linux/suspend.h>
>  #include <linux/vmalloc.h>
> +#include <linux/efi.h>
>  
>  #include <asm/init.h>
>  #include <asm/pgtable.h>
> @@ -29,6 +30,48 @@
>  #include <asm/setup.h>
>  #include <asm/set_memory.h>
>  
> +#ifdef CONFIG_ACPI
> +/**

Two stars '**' are kernel-doc style but this comment is implementation
detail and is irrelevant for kernel-doc ouput.

> + * Used while adding mapping for ACPI tables.
> + * Can be reused when other iomem regions need be mapped
> + */
> +struct init_pgtable_data {
> +	struct x86_mapping_info *info;
> +	pgd_t *level4p;
> +};
> +
> +static int mem_region_callback(struct resource *res, void *arg)
> +{
> +	struct init_pgtable_data *data = arg;
> +	unsigned long mstart, mend;
> +
> +	mstart = res->start;
> +	mend = mstart + resource_size(res) - 1;
> +
> +	return kernel_ident_mapping_init(data->info,
> +			data->level4p, mstart, mend);

Do not break that line.

> +}
> +
> +static int init_acpi_pgtable(struct x86_mapping_info *info,
> +				   pgd_t *level4p)

static int
map_acpi_tables(...)

> +{
> +	unsigned long flags = IORESOURCE_MEM | IORESOURCE_BUSY;
> +	struct init_pgtable_data data;
> +
> +	data.info = info;
> +	data.level4p = level4p;
> +	flags = IORESOURCE_MEM | IORESOURCE_BUSY;
> +	return walk_iomem_res_desc(IORES_DESC_ACPI_TABLES, flags, 0, -1,
> +				   &data, mem_region_callback);
> +}
> +#else
> +static int init_acpi_pgtable(struct x86_mapping_info *info,
> +				   pgd_t *level4p)
> +{
> +	return 0;
> +}
> +#endif
> +
>  #ifdef CONFIG_KEXEC_FILE
>  const struct kexec_file_ops * const kexec_file_loaders[] = {
>  		&kexec_bzImage64_ops,
> @@ -36,6 +79,37 @@ const struct kexec_file_ops * const kexec_file_loaders[] = {
>  };
>  #endif
>  
> +#ifdef CONFIG_EFI
> +static int init_efi_systab_pgtable(struct x86_mapping_info *info,
> +				   pgd_t *level4p)

This function's name is wrong. Make it like this:

static int
map_efi_systab(struct x86_mapping_info *info, pgd_t *level4p)
{
#ifdef CONFIG_EFI

	...

#endif

	return 0;
}

and drop the #else ifdeffery.


> +{
> +	unsigned long mstart, mend;
> +
> +	if (!efi_enabled(EFI_BOOT))
> +		return 0;
> +
> +	mstart = (boot_params.efi_info.efi_systab |
> +			((u64)boot_params.efi_info.efi_systab_hi<<32));
> +
> +	if (efi_enabled(EFI_64BIT))
> +		mend = mstart + sizeof(efi_system_table_64_t);
> +	else
> +		mend = mstart + sizeof(efi_system_table_32_t);
> +
> +	if (mstart)
> +		return kernel_ident_mapping_init(info,
> +				level4p, mstart, mend);

Flip that logic:

	if (!mstart)
		return 0;

	return kernel_ident_mapping_init(info, level4p, mstart, mend);

and let the function stick out.

> +
> +	return 0;
> +}
> +#else
> +static inline int init_efi_systab_pgtable(struct x86_mapping_info *info,
> +					  pgd_t *level4p)
> +{
> +	return 0;
> +}
> +#endif
> +
>  static void free_transition_pgtable(struct kimage *image)
>  {
>  	free_page((unsigned long)image->arch.p4d);
> @@ -159,6 +233,18 @@ static int init_pgtable(struct kimage *image, unsigned long start_pgtable)
>  			return result;
>  	}
>  
> +	/**

Two stars '**' are kernel-doc style comments above function names but
not here.

> +	 * Prepare EFI systab and ACPI table mapping for kexec kernel,
> +	 * since they are not covered by pfn_mapped.
> +	 */
> +	result = init_efi_systab_pgtable(&info, level4p);
> +	if (result)
> +		return result;
> +
> +	result = init_acpi_pgtable(&info, level4p);
> +	if (result)
> +		return result;
> +
>  	return init_transition_pgtable(image, level4p);
>  }
>  
> -- 
> 2.17.2
> 

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.

  reply	other threads:[~2019-04-27 16:11 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-24  9:29 [PATCH v5 0/2] x86/boot: Use efi_setup_data for searching RSDP on kexec-ed kernel Baoquan He
2019-04-24  9:29 ` [PATCH v5 1/2] x86/kexec: Build identity mapping for EFI systab and ACPI tables Baoquan He
2019-04-27 16:11   ` Borislav Petkov [this message]
2019-04-28  5:41     ` Baoquan He
2019-04-29 12:50       ` Borislav Petkov
2019-04-29  0:23   ` [PATCH v6 " Baoquan He
2019-04-29 13:55     ` Borislav Petkov
2019-04-29 14:16       ` Baoquan He
2019-05-13  1:43       ` Baoquan He
2019-05-13  7:07         ` Borislav Petkov
2019-05-13  7:32           ` Baoquan He
2019-05-13  7:50             ` Borislav Petkov
2019-05-13  8:02               ` Baoquan He
2019-05-15  5:17                 ` Junichi Nomura
2019-05-15  6:58                   ` Borislav Petkov
2019-05-15  7:09                     ` Junichi Nomura
2019-05-21  9:02                       ` Kairui Song
2019-05-21 10:43                         ` Junichi Nomura
2019-05-21 18:09                         ` Borislav Petkov
2019-05-28  2:49                           ` Kairui Song
2019-06-06 19:20                             ` Borislav Petkov
2019-05-13  8:06               ` Baoquan He
2019-05-14  3:22                 ` Dave Young
2019-05-14  3:33                   ` Baoquan He
2019-05-21 21:53                     ` Dirk van der Merwe
2019-05-21 23:04                       ` Borislav Petkov
2019-05-14  8:48                   ` Dave Young
2019-05-14 11:18                     ` Kairui Song
2019-05-14 11:38                     ` Peter Zijlstra
2019-05-14 12:58                       ` Dave Young
2019-05-14 13:54                         ` Peter Zijlstra
2019-05-14 14:09                         ` Ingo Molnar
2019-05-15  1:08                           ` Dave Young
2019-05-15  6:43                             ` Junichi Nomura
2019-05-17 13:41                   ` Borislav Petkov
2019-05-17 13:50                     ` [PATCH] x86/boot: Call get_rsdp_addr() after console_init() Borislav Petkov
2019-05-21  9:28                       ` Baoquan He
2019-06-06 19:22     ` [tip:x86/boot] x86/kexec: Add the EFI system tables and ACPI tables to the ident map tip-bot for Kairui Song
2019-04-24  9:29 ` [PATCH v5 2/2] x86/boot: Use efi_setup_data for searching RSDP on kexec-ed kernels Baoquan He
2019-04-24  9:33   ` Baoquan He
2019-04-24  9:38 ` [PATCH v5 0/2] x86/boot: Use efi_setup_data for searching RSDP on kexec-ed kernel Borislav Petkov
2019-04-24 10:00   ` Baoquan He

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