From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Reply-To: pmorel@linux.ibm.com Subject: Re: [PATCH 4/4] vfio: vfio_iommu_type1: implement VFIO_IOMMU_INFO_CAPABILITIES References: <1557476555-20256-1-git-send-email-pmorel@linux.ibm.com> <1557476555-20256-5-git-send-email-pmorel@linux.ibm.com> <20190516124026.415bf671@x1.home> From: Pierre Morel Date: Fri, 17 May 2019 10:17:17 +0200 MIME-Version: 1.0 In-Reply-To: <20190516124026.415bf671@x1.home> Content-Type: text/plain; charset="utf-8"; format="flowed" Content-Language: en-US Content-Transfer-Encoding: 8bit Message-Id: <29209ea1-be49-47bc-c258-6e87da055fac@linux.ibm.com> Sender: kvm-owner@vger.kernel.org List-Archive: List-Post: To: Alex Williamson Cc: sebott@linux.vnet.ibm.com, gerald.schaefer@de.ibm.com, pasic@linux.vnet.ibm.com, borntraeger@de.ibm.com, walling@linux.ibm.com, linux-s390@vger.kernel.org, iommu@lists.linux-foundation.org, joro@8bytes.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com List-ID: On 16/05/2019 20:40, Alex Williamson wrote: > On Fri, 10 May 2019 10:22:35 +0200 > Pierre Morel wrote: > >> We implement a capability intercafe for VFIO_IOMMU_GET_INFO and add the >> first capability: VFIO_IOMMU_INFO_CAPABILITIES. >> >> When calling the ioctl, the user must specify >> VFIO_IOMMU_INFO_CAPABILITIES to retrieve the capabilities and must check >> in the answer if capabilities are supported. >> Older kernel will not check nor set the VFIO_IOMMU_INFO_CAPABILITIES in >> the flags of vfio_iommu_type1_info. >> >> The iommu get_attr callback will be called to retrieve the specific >> attributes and fill the capabilities, VFIO_IOMMU_INFO_CAP_QFN for the >> PCI query function attributes and VFIO_IOMMU_INFO_CAP_QGRP for the >> PCI query function group. >> >> Signed-off-by: Pierre Morel >> --- >> drivers/vfio/vfio_iommu_type1.c | 95 ++++++++++++++++++++++++++++++++++++++++- >> 1 file changed, 94 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c >> index d0f731c..f7f8120 100644 >> --- a/drivers/vfio/vfio_iommu_type1.c >> +++ b/drivers/vfio/vfio_iommu_type1.c >> @@ -1658,6 +1658,70 @@ static int vfio_domains_have_iommu_cache(struct vfio_iommu *iommu) >> return ret; >> } >> >> +int vfio_iommu_type1_caps(struct vfio_iommu *iommu, struct vfio_info_cap *caps, >> + size_t size) >> +{ >> + struct vfio_domain *d; >> + struct vfio_iommu_type1_info_block *info_fn; >> + struct vfio_iommu_type1_info_block *info_grp; >> + unsigned long total_size, fn_size, grp_size; >> + int ret; >> + >> + d = list_first_entry(&iommu->domain_list, struct vfio_domain, next); >> + if (!d) >> + return -ENODEV; >> + /* The size of these capabilities are device dependent */ >> + fn_size = iommu_domain_get_attr(d->domain, >> + DOMAIN_ATTR_ZPCI_FN_SIZE, NULL); >> + if (fn_size < 0) >> + return fn_size; > > What if non-Z archs want to use this? The function is architected > specifically for this one use case, fail if any component is not there > which means it requires a re-write to add further support. If > ZPCI_FN_SIZE isn't support, move on to the next thing. yes, clear. > >> + fn_size += sizeof(struct vfio_info_cap_header); >> + total_size = fn_size; > > Here too, total_size should be initialized to zero and each section += > the size they'd like to add. thanks, clear too. > >> + >> + grp_size = iommu_domain_get_attr(d->domain, >> + DOMAIN_ATTR_ZPCI_GRP_SIZE, NULL); >> + if (grp_size < 0) >> + return grp_size; >> + grp_size += sizeof(struct vfio_info_cap_header); >> + total_size += grp_size; >> + >> + /* Tell caller to call us with a greater buffer */ >> + if (total_size > size) { >> + caps->size = total_size; >> + return 0; >> + } >> + >> + info_fn = kzalloc(fn_size, GFP_KERNEL); >> + if (!info_fn) >> + return -ENOMEM; > > Maybe fn_size was zero because we're not on Z. > >> + ret = iommu_domain_get_attr(d->domain, >> + DOMAIN_ATTR_ZPCI_FN, &info_fn->data); > > Kernel internal structures != user api. Thanks, > > Alex Thanks a lot Alex, I understand the concerns, I was too focussed on Z, I will rework this as you said: - definition of the user API and - take care that another architecture may want to use the interface. Regards, Pierre -- Pierre Morel Linux/KVM/QEMU in Böblingen - Germany