From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pierre Morel Subject: Re: [PATCH] vfio/iommu_type1: report the IOMMU aperture info Date: Thu, 30 Nov 2017 15:49:36 +0100 Message-ID: <76879d8a-3c5f-2fb0-c8f9-100368eafa6e@linux.vnet.ibm.com> References: <1512041678-4563-1-git-send-email-pmorel@linux.vnet.ibm.com> <1ad1aff9-1651-d1a9-cd1b-07bfd7dd0817@arm.com> <7cf3e03e-e9b4-0e27-098b-3bc391abcf96@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 8bit Cc: "cohuck@redhat.com" , "borntraeger@de.ibm.com" , "zyimin@linux.vnet.ibm.com" , "pasic@linux.vnet.ibm.com" , "kvm@vger.kernel.org" , "linux-kernel@vger.kernel.org" To: Jean-Philippe Brucker , "alex.williamson@redhat.com" Return-path: In-Reply-To: <7cf3e03e-e9b4-0e27-098b-3bc391abcf96@linux.vnet.ibm.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 30/11/2017 15:16, Pierre Morel wrote: > On 30/11/2017 13:57, Jean-Philippe Brucker wrote: >> Hello, >> >> On 30/11/17 11:34, Pierre Morel wrote: >> [...] >>> +/** >>> + * vfio_get_aperture - report minimal aperture of a vfio_iommu >>> + * @iommu: the current vfio_iommu >>> + * @start: a pointer to the aperture start >>> + * @end  : a pointer to the aperture end >>> + * >>> + * This function iterate on the domains using the given vfio_iommu >>> + * and restrict the aperture to the minimal aperture common >>> + * to all domains sharing this vfio_iommu. >>> + */ >>> +static void vfio_get_aperture(struct vfio_iommu *iommu, uint64_t >>> *start, >>> +                uint64_t *end) >>> +{ >>> +    struct iommu_domain_geometry geometry; >>> +    struct vfio_domain *domain; >>> + >>> +    *start = 0; >>> +    *end = U64_MAX; >> >> I wonder if the default values should also reflect what the VFIO >> implementation actually supports. Looking at vfio_dma_do_map, a 32-bit >> host will reject any iova greater than 32 bits. In addition, >> vfio_dma_do_unmap doesn't support unmapping the last page of a 64-bit >> address space (existing IOMMUs would probably reject map requests with >> IOVA > 52 bits anyway, but if they don't report a domain aperture, VFIO >> can't guess it). >> >> I think it's convenient to use VFIO_IOMMU_UNMAP_DMA on the full address >> space when an unmap-all is needed, maybe we could provide default >> aperture >> values that help doing this? (~0U for 32-bit and (~0ULL - PAGE_SIZE) for >> 64-bit) indeed the error is to use uint64_t, I should *never* use this hardware specific values but simply unsigned long and -1UL/~0U at this level. Shouldn't the 52bit problem be reported by the iommu geometry? >> >> Thanks, >> Jean >> > > Thanks, I will take care of this. > > Pierre > > -- Pierre Morel Linux/KVM/QEMU in Böblingen - Germany