Messages in this thread | | | Subject | Re: [PATCH] vfio/iommu_type1: report the IOMMU aperture info | From | Pierre Morel <> | Date | Thu, 30 Nov 2017 16:11:35 +0100 |
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On 30/11/2017 15:08, Alex Williamson wrote: > On Thu, 30 Nov 2017 12:34:38 +0100 > Pierre Morel <pmorel@linux.vnet.ibm.com> wrote: > >> When userland VFIO defines a new IOMMU for a guest it may >> want to specify to the guest the physical limits of >> the underlying host IOMMU to avoid access to forbidden >> memory ranges. >> >> Currently, the vfio_iommu_type1 driver does not report this >> information to userland. >> >> Let's extend the vfio_iommu_type1_info structure reported >> by the ioctl VFIO_IOMMU_GET_INFO command to report the >> IOMMU limits as new uint64_t entries aperture_start and >> aperture_end. >> >> Let's also extend the flags bit map to add a flag specifying >> if this extension of the info structure is reported or not. >> >> Signed-off-by: Pierre Morel <pmorel@linux.vnet.ibm.com> >> --- >> drivers/vfio/vfio_iommu_type1.c | 42 +++++++++++++++++++++++++++++++++++++++++ >> include/uapi/linux/vfio.h | 3 +++ >> 2 files changed, 45 insertions(+) >> >> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c >> index 8549cb1..7da5fe0 100644 >> --- a/drivers/vfio/vfio_iommu_type1.c >> +++ b/drivers/vfio/vfio_iommu_type1.c >> @@ -1526,6 +1526,40 @@ static int vfio_domains_have_iommu_cache(struct vfio_iommu *iommu) >> return ret; >> } >> >> +/** >> + * 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; >> + >> + mutex_lock(&iommu->lock); >> + /* loop on all domains using this vfio_iommu */ >> + list_for_each_entry(domain, &iommu->domain_list, next) { >> + iommu_domain_get_attr(domain->domain, DOMAIN_ATTR_GEOMETRY, >> + &geometry); >> + if (geometry.force_aperture) { >> + if (geometry.aperture_start > *start) >> + *start = geometry.aperture_start; >> + if (geometry.aperture_end < *end) >> + *end = geometry.aperture_end; >> + } >> + } >> + mutex_unlock(&iommu->lock); >> +} >> + >> static long vfio_iommu_type1_ioctl(void *iommu_data, >> unsigned int cmd, unsigned long arg) >> { >> @@ -1560,6 +1594,14 @@ static long vfio_iommu_type1_ioctl(void *iommu_data, >> >> info.iova_pgsizes = vfio_pgsize_bitmap(iommu); >> >> + minsz = min_t(size_t, info.argsz, sizeof(info)); >> + if (minsz >= offsetofend(struct vfio_iommu_type1_info, >> + aperture_end)) { >> + info.flags |= VFIO_IOMMU_INFO_APERTURE; >> + vfio_get_aperture(iommu, &info.aperture_start, >> + &info.aperture_end); >> + } >> + >> return copy_to_user((void __user *)arg, &info, minsz) ? >> -EFAULT : 0; >> >> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h >> index 0fb25fb..780d909 100644 >> --- a/include/uapi/linux/vfio.h >> +++ b/include/uapi/linux/vfio.h >> @@ -519,6 +519,9 @@ struct vfio_iommu_type1_info { >> __u32 flags; >> #define VFIO_IOMMU_INFO_PGSIZES (1 << 0) /* supported page sizes info */ >> __u64 iova_pgsizes; /* Bitmap of supported page sizes */ >> +#define VFIO_IOMMU_INFO_APERTURE (1 << 1) /* supported aperture info */ >> + __u64 aperture_start; /* start of DMA aperture */ >> + __u64 aperture_end; /* end of DMA aperture */ >> }; >> >> #define VFIO_IOMMU_GET_INFO _IO(VFIO_TYPE, VFIO_BASE + 12) > > This only supports the most simple topology, even x86 cannot claim to > have a single contiguous aperture, it's typically bisected by an MSI > window. I think we need an API that supports one or more apertures > out of the box. Also as Eric indicates, a capability is probably the > better option for creating a flexible structure. Thanks, > > Alex >
Yes, I understand that a capability here is a must, I will follow this way.
For having multiple aperture and MSI protection, I understood it was done using windows and reserved regions. Can you point me to my error?
Thanks,
Pierre
-- Pierre Morel Linux/KVM/QEMU in Böblingen - Germany
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