Re: [PATCH 05/35] s390/mm: provide memory management functions for protected KVM guests

[Christian Borntraeger <borntraeger@de.ibm.com>]

On 12.02.20 14:42, Cornelia Huck wrote:
> On Fri,  7 Feb 2020 06:39:28 -0500
> Christian Borntraeger <borntraeger@de.ibm.com> wrote:
> 
>> From: Claudio Imbrenda <imbrenda@linux.ibm.com>
>>
>> This provides the basic ultravisor calls and page table handling to cope
>> with secure guests:
>> - provide arch_make_page_accessible
>> - make pages accessible after unmapping of secure guests
>> - provide the ultravisor commands convert to/from secure
>> - provide the ultravisor commands pin/unpin shared
>> - provide callbacks to make pages secure (inacccessible)
>>  - we check for the expected pin count to only make pages secure if the
>>    host is not accessing them
>>  - we fence hugetlbfs for secure pages
>>
>> Co-developed-by: Ulrich Weigand <Ulrich.Weigand@de.ibm.com>
>> Signed-off-by: Ulrich Weigand <Ulrich.Weigand@de.ibm.com>
>> Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
>> [borntraeger@de.ibm.com: patch merging, splitting, fixing]
>> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
>> ---
>>  arch/s390/include/asm/gmap.h        |   2 +
>>  arch/s390/include/asm/mmu.h         |   2 +
>>  arch/s390/include/asm/mmu_context.h |   1 +
>>  arch/s390/include/asm/page.h        |   5 +
>>  arch/s390/include/asm/pgtable.h     |  34 +++++-
>>  arch/s390/include/asm/uv.h          |  52 +++++++++
>>  arch/s390/kernel/uv.c               | 172 ++++++++++++++++++++++++++++
>>  7 files changed, 263 insertions(+), 5 deletions(-)
> 
> (...)
> 
>> +/*
>> + * Requests the Ultravisor to encrypt a guest page and make it
>> + * accessible to the host for paging (export).
>> + *
>> + * @paddr: Absolute host address of page to be exported
>> + */
>> +int uv_convert_from_secure(unsigned long paddr)
>> +{
>> +	struct uv_cb_cfs uvcb = {
>> +		.header.cmd = UVC_CMD_CONV_FROM_SEC_STOR,
>> +		.header.len = sizeof(uvcb),
>> +		.paddr = paddr
>> +	};
>> +
>> +	uv_call(0, (u64)&uvcb);
>> +
>> +	if (uvcb.header.rc == 1 || uvcb.header.rc == 0x107)
> 
> I think this either wants a comment or some speaking #defines.

Yes. We will improve some other aspects of this patch, but I will add

	/* Return on success or if this page was already exported */
> 
>> +		return 0;
>> +	return -EINVAL;
>> +}
> 
> (...)
>