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SubjectRe: [RFC PATCH v3 09/20] x86: Insure that boot memory areas are mapped properly
On Wed, Nov 09, 2016 at 06:36:20PM -0600, Tom Lendacky wrote:
> The boot data and command line data are present in memory in an
> un-encrypted state and are copied early in the boot process. The early
> page fault support will map these areas as encrypted, so before attempting
> to copy them, add unencrypted mappings so the data is accessed properly
> when copied.
>
> For the initrd, encrypt this data in place. Since the future mapping of the
> initrd area will be mapped as encrypted the data will be accessed properly.
>
> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
> ---
> arch/x86/include/asm/mem_encrypt.h | 13 ++++++++
> arch/x86/kernel/head64.c | 21 ++++++++++++--
> arch/x86/kernel/setup.c | 9 ++++++
> arch/x86/mm/mem_encrypt.c | 56 ++++++++++++++++++++++++++++++++++++
> 4 files changed, 96 insertions(+), 3 deletions(-)

...

> @@ -122,6 +131,12 @@ static void __init copy_bootdata(char *real_mode_data)
> char * command_line;
> unsigned long cmd_line_ptr;
>
> + /*
> + * If SME is active, this will create un-encrypted mappings of the
> + * boot data in advance of the copy operations
^
|
Fullstop--+

> + */
> + sme_map_bootdata(real_mode_data);
> +
> memcpy(&boot_params, real_mode_data, sizeof boot_params);
> sanitize_boot_params(&boot_params);
> cmd_line_ptr = get_cmd_line_ptr();

...

> diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
> index 06235b4..411210d 100644
> --- a/arch/x86/mm/mem_encrypt.c
> +++ b/arch/x86/mm/mem_encrypt.c
> @@ -16,8 +16,11 @@
>
> #include <asm/tlbflush.h>
> #include <asm/fixmap.h>
> +#include <asm/setup.h>
> +#include <asm/bootparam.h>
>
> extern pmdval_t early_pmd_flags;
> +int __init __early_make_pgtable(unsigned long, pmdval_t);
>
> /*
> * Since sme_me_mask is set early in the boot process it must reside in
> @@ -126,6 +129,59 @@ void __init sme_early_mem_dec(resource_size_t paddr, unsigned long size)
> }
> }
>
> +static void __init *sme_bootdata_mapping(void *vaddr, unsigned long size)

So this could be called __sme_map_bootdata(). "sme_bootdata_mapping"
doesn't tell me what the function does as there's no verb in the name.

> +{
> + unsigned long paddr = (unsigned long)vaddr - __PAGE_OFFSET;
> + pmdval_t pmd_flags, pmd;
> + void *ret = vaddr;

That *ret --->

> +
> + /* Use early_pmd_flags but remove the encryption mask */
> + pmd_flags = early_pmd_flags & ~sme_me_mask;
> +
> + do {
> + pmd = (paddr & PMD_MASK) + pmd_flags;
> + __early_make_pgtable((unsigned long)vaddr, pmd);
> +
> + vaddr += PMD_SIZE;
> + paddr += PMD_SIZE;
> + size = (size < PMD_SIZE) ? 0 : size - PMD_SIZE;

size <= PMD_SIZE

looks more obvious to me...
> + } while (size);
> +
> + return ret;

---> is simply passing vaddr out. So the function can be just as well be
void and you can do below:
__sme_map_bootdata(real_mode_data, sizeof(boot_params));

boot_data = (struct boot_params *)real_mode_data;

...

> +void __init sme_map_bootdata(char *real_mode_data)
> +{
> + struct boot_params *boot_data;
> + unsigned long cmdline_paddr;
> +
> + if (!sme_me_mask)
> + return;
> +
> + /*
> + * The bootdata will not be encrypted, so it needs to be mapped
> + * as unencrypted data so it can be copied properly.
> + */
> + boot_data = sme_bootdata_mapping(real_mode_data, sizeof(boot_params));
> +
> + /*
> + * Determine the command line address only after having established
> + * the unencrypted mapping.
> + */
> + cmdline_paddr = boot_data->hdr.cmd_line_ptr |
> + ((u64)boot_data->ext_cmd_line_ptr << 32);

<---- newline here.
> + if (cmdline_paddr)
> + sme_bootdata_mapping(__va(cmdline_paddr), COMMAND_LINE_SIZE);
> +}
> +
> +void __init sme_encrypt_ramdisk(resource_size_t paddr, unsigned long size)
> +{
> + if (!sme_me_mask)
> + return;
> +
> + sme_early_mem_enc(paddr, size);
> +}

So this one could simply be called sme_encrypt_area() and be used for
other things. There's nothing special about encrypting a ramdisk, by the
looks of it.

--
Regards/Gruss,
Boris.

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

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