# Re: \[PATCH Part2 v5 05/45\] x86/sev: Add helper functions for RMPUPDATE and PSMASH instruction

- From: Brijesh Singh \<hidden\>
- Date: 2021-09-27 16:06:14 
- List: linux-crypto
- Page: https://ratatoskr.run/linux-crypto/2021/09/1522870
- Thread: https://ratatoskr.run/kvm/2021/08/1484154/t/2.md

```text


On 9/24/21 9:04 AM, Borislav Petkov wrote:
> On Fri, Aug 20, 2021 at 10:58:38AM -0500, Brijesh Singh wrote:
>> The RMPUPDATE instruction writes a new RMP entry in the RMP Table. The
>> hypervisor will use the instruction to add pages to the RMP table. See
>> APM3 for details on the instruction operations.
>>
>> The PSMASH instruction expands a 2MB RMP entry into a corresponding set of
>> contiguous 4KB-Page RMP entries. The hypervisor will use this instruction
>> to adjust the RMP entry without invalidating the previous RMP entry.
>>
>> Signed-off-by: Brijesh Singh <redacted>
>> ---
>>   arch/x86/include/asm/sev.h | 11 ++++++
>>   arch/x86/kernel/sev.c      | 72 ++++++++++++++++++++++++++++++++++++++
>>   2 files changed, 83 insertions(+)
>>
>> diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
>> index 5b1a6a075c47..92ced9626e95 100644
>> --- a/arch/x86/include/asm/sev.h
>> +++ b/arch/x86/include/asm/sev.h
>> @@ -78,7 +78,9 @@ extern bool handle_vc_boot_ghcb(struct pt_regs *regs);
>>   
>>   /* RMP page size */
>>   #define RMP_PG_SIZE_4K			0
>> +#define RMP_PG_SIZE_2M			1
>>   #define RMP_TO_X86_PG_LEVEL(level)	(((level) == RMP_PG_SIZE_4K) ? PG_LEVEL_4K : PG_LEVEL_2M)
>> +#define X86_TO_RMP_PG_LEVEL(level)	(((level) == PG_LEVEL_4K) ? RMP_PG_SIZE_4K : RMP_PG_SIZE_2M)
>>   
>>   /*
>>    * The RMP entry format is not architectural. The format is defined in PPR
>> @@ -107,6 +109,15 @@ struct __packed rmpentry {
>>   
>>   #define RMPADJUST_VMSA_PAGE_BIT		BIT(16)
>>   
>> +struct rmpupdate {
>
> Function is called the same way - maybe this should be called
> rmpupdate_desc or so.

Noted.


>> +
>> +	return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(psmash);
>
> That's for kvm?

Yes.

...

>> +EXPORT_SYMBOL_GPL(rmp_make_shared);
>
> Both exports for kvm I assume?

yes, both KVM and CCP drivers need them.

thanks
```