From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:40176 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726004AbhATMki (ORCPT ); Wed, 20 Jan 2021 07:40:38 -0500 Subject: Re: [kvm-unit-tests PATCH v3 2/3] s390x: define UV compatible I/O allocation References: <1611085944-21609-1-git-send-email-pmorel@linux.ibm.com> <1611085944-21609-3-git-send-email-pmorel@linux.ibm.com> <2558695f-4ab7-d6e9-c857-0e8473ada775@redhat.com> From: Pierre Morel Message-ID: <4a9ae9a8-892b-3456-526e-1a46bf2c85dc@linux.ibm.com> Date: Wed, 20 Jan 2021 13:39:51 +0100 MIME-Version: 1.0 In-Reply-To: <2558695f-4ab7-d6e9-c857-0e8473ada775@redhat.com> Content-Type: text/plain; charset="utf-8"; format="flowed" Content-Language: en-US Content-Transfer-Encoding: 8bit List-ID: To: Thomas Huth , kvm@vger.kernel.org Cc: linux-s390@vger.kernel.org, frankja@linux.ibm.com, david@redhat.com, cohuck@redhat.com, imbrenda@linux.ibm.com, drjones@redhat.com, pbonzini@redhat.com On 1/20/21 12:01 PM, Thomas Huth wrote: > On 19/01/2021 20.52, Pierre Morel wrote: >> To centralize the memory allocation for I/O we define >> the alloc_io_page/free_io_page functions which share the I/O >> memory with the host in case the guest runs with >> protected virtualization. >> >> Signed-off-by: Pierre Morel >> --- >>   lib/s390x/malloc_io.c | 50 +++++++++++++++++++++++++++++++++++++++++++ >>   lib/s390x/malloc_io.h | 18 ++++++++++++++++ >>   s390x/Makefile        |  1 + >>   3 files changed, 69 insertions(+) >>   create mode 100644 lib/s390x/malloc_io.c >>   create mode 100644 lib/s390x/malloc_io.h >> >> diff --git a/lib/s390x/malloc_io.c b/lib/s390x/malloc_io.c >> new file mode 100644 >> index 0000000..2a946e0 >> --- /dev/null >> +++ b/lib/s390x/malloc_io.c >> @@ -0,0 +1,50 @@ >> +/* >> + * I/O page allocation >> + * >> + * Copyright (c) 2021 IBM Corp >> + * >> + * Authors: >> + *  Pierre Morel >> + * >> + * This code is free software; you can redistribute it and/or modify it >> + * under the terms of the GNU General Public License version 2. > > Janosch recently started to introduce SPDX identifieres to the s390x > code, so I think it would be good to use them here, too. > >> + * Using this interface provide host access to the allocated pages in >> + * case the guest is a secure guest. >> + * This is needed for I/O buffers. >> + * >> + */ >> +#include >> +#include >> +#include >> +#include >> +#include >> +#include >> + >> +void *alloc_io_page(int size) >> +{ >> +    void *p; >> + >> +    assert(size <= PAGE_SIZE); > > Apart from the assert() statement, the size parameter seems to be > completely unused. It's also weird to have the function named right. > alloc_something_page() and then have a parameter that takes bytes. Thus > I'd suggest to either drop the size parameter completely, or to rename > the function to alloc_io_mem and then to alloc multiple pages below in > case the size is bigger than PAGE_SIZE. Or maybe even to name the > function alloc_io_pages and then use "int num_pages" as a parameter, > allowing to allocate multiple pages at once? OK, may bet using order as with the alloc_pages_flags would be fine. Then I will need a new flag in the pages. > >> + >> +    p = alloc_pages_flags(1, AREA_DMA31); humm 0 here (Claudio) >> +    if (!p) >> +        return NULL; >> +    memset(p, 0, PAGE_SIZE); >> + >> +    if (!test_facility(158)) >> +        return p; >> + >> +    if (uv_set_shared((unsigned long)p) == 0) >> +        return p; >> + >> +    free_pages(p); >> +    return NULL; >> +} >> + >> +void free_io_page(void *p) >> +{ >> +    if (test_facility(158)) >> +        uv_remove_shared((unsigned long)p); >> +    free_pages(p); >> +} >> diff --git a/lib/s390x/malloc_io.h b/lib/s390x/malloc_io.h >> new file mode 100644 >> index 0000000..f780191 >> --- /dev/null >> +++ b/lib/s390x/malloc_io.h >> @@ -0,0 +1,18 @@ >> +/* >> + * I/O allocations >> + * >> + * Copyright (c) 2021 IBM Corp >> + * >> + * Authors: >> + *  Pierre Morel >> + * >> + * This code is free software; you can redistribute it and/or modify it >> + * under the terms of the GNU General Public License version 2. >> + */ > Please also add SPDX license information here. Will do. Thanks for reviewing, Pierre > >  Thomas > -- Pierre Morel IBM Lab Boeblingen