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

[Cornelia Huck <cohuck@redhat.com>]

On Thu, 13 Feb 2020 08:43:33 +0100
Christian Borntraeger <borntraeger@de.ibm.com> wrote:

> 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 */

Sounds good.

> >   
> >> +		return 0;
> >> +	return -EINVAL;
> >> +}  
> > 
> > (...)
> >   
>