# git rev-parse -q --verify 76fa4975f3ed12d15762bc979ca44078598ed8ee^{commit}
# git fetch -q -n -f git://gitlab.ozlabs.ibm.com/linuxppc/linux.git fixes-test
# git rev-parse -q --verify 76fa4975f3ed12d15762bc979ca44078598ed8ee^{commit}
76fa4975f3ed12d15762bc979ca44078598ed8ee
# git checkout -q -f -B kisskb 76fa4975f3ed12d15762bc979ca44078598ed8ee
# git clean -qxdf
# < git log -1
# commit 76fa4975f3ed12d15762bc979ca44078598ed8ee
# Author: Alexey Kardashevskiy <aik@ozlabs.ru>
# Date:   Tue Jul 17 17:19:13 2018 +1000
# 
#     KVM: PPC: Check if IOMMU page is contained in the pinned physical page
#     
#     A VM which has:
#      - a DMA capable device passed through to it (eg. network card);
#      - running a malicious kernel that ignores H_PUT_TCE failure;
#      - capability of using IOMMU pages bigger that physical pages
#     can create an IOMMU mapping that exposes (for example) 16MB of
#     the host physical memory to the device when only 64K was allocated to the VM.
#     
#     The remaining 16MB - 64K will be some other content of host memory, possibly
#     including pages of the VM, but also pages of host kernel memory, host
#     programs or other VMs.
#     
#     The attacking VM does not control the location of the page it can map,
#     and is only allowed to map as many pages as it has pages of RAM.
#     
#     We already have a check in drivers/vfio/vfio_iommu_spapr_tce.c that
#     an IOMMU page is contained in the physical page so the PCI hardware won't
#     get access to unassigned host memory; however this check is missing in
#     the KVM fastpath (H_PUT_TCE accelerated code). We were lucky so far and
#     did not hit this yet as the very first time when the mapping happens
#     we do not have tbl::it_userspace allocated yet and fall back to
#     the userspace which in turn calls VFIO IOMMU driver, this fails and
#     the guest does not retry,
#     
#     This stores the smallest preregistered page size in the preregistered
#     region descriptor and changes the mm_iommu_xxx API to check this against
#     the IOMMU page size.
#     
#     This calculates maximum page size as a minimum of the natural region
#     alignment and compound page size. For the page shift this uses the shift
#     returned by find_linux_pte() which indicates how the page is mapped to
#     the current userspace - if the page is huge and this is not a zero, then
#     it is a leaf pte and the page is mapped within the range.
#     
#     Fixes: 121f80ba68f1 ("KVM: PPC: VFIO: Add in-kernel acceleration for VFIO")
#     Cc: stable@vger.kernel.org # v4.12+
#     Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
#     Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
#     Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
# < /opt/cross/kisskb/gcc-4.6.3-nolibc/ia64-linux/bin/ia64-linux-gcc --version
# < git log --format=%s --max-count=1 76fa4975f3ed12d15762bc979ca44078598ed8ee
# < make -s -j 48 ARCH=ia64 O=/kisskb/build/powerpc-fixes_ia64-defconfig_ia64 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/ia64-linux/bin/ia64-linux-  defconfig
# make -s -j 48 ARCH=ia64 O=/kisskb/build/powerpc-fixes_ia64-defconfig_ia64 CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/ia64-linux/bin/ia64-linux-  
/kisskb/src/net/Makefile:24: CC cannot link executables. Skipping bpfilter.
<stdin>:1185:2: warning: #warning syscall perf_event_open not implemented [-Wcpp]
<stdin>:1239:2: warning: #warning syscall seccomp not implemented [-Wcpp]
<stdin>:1317:2: warning: #warning syscall pkey_mprotect not implemented [-Wcpp]
<stdin>:1320:2: warning: #warning syscall pkey_alloc not implemented [-Wcpp]
<stdin>:1323:2: warning: #warning syscall pkey_free not implemented [-Wcpp]
<stdin>:1326:2: warning: #warning syscall statx not implemented [-Wcpp]
<stdin>:1332:2: warning: #warning syscall io_pgetevents not implemented [-Wcpp]
<stdin>:1335:2: warning: #warning syscall rseq not implemented [-Wcpp]
/kisskb/src/kernel/cgroup/cgroup-v1.c: In function 'cgroup1_mount':
/kisskb/src/kernel/cgroup/cgroup-v1.c:1256:20: warning: 'root' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/net/Makefile:24: CC cannot link executables. Skipping bpfilter.
/kisskb/src/kernel/printk/printk.c: In function 'devkmsg_sysctl_set_loglvl':
/kisskb/src/kernel/printk/printk.c:183:16: warning: 'old' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/kernel/fork.c:700:13: warning: 'task_struct_whitelist' defined but not used [-Wunused-function]
/kisskb/src/mm/vmstat.c: In function 'sysctl_vm_numa_stat_handler':
/kisskb/src/mm/vmstat.c:89:5: warning: 'oldval' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/fs/proc/inode.c: In function 'proc_reg_open':
/kisskb/src/include/linux/list.h:65:12: warning: 'pdeo' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/fs/proc/inode.c:339:21: note: 'pdeo' was declared here
/kisskb/src/fs/nfsd/nfs4xdr.c: In function 'nfsd4_encode_components_esc':
/kisskb/src/fs/nfsd/nfs4xdr.c:2046:9: warning: 'str' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/fs/udf/unicode.c: In function 'udf_name_conv_char':
/kisskb/src/fs/udf/unicode.c:132:8: warning: 'c' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/drivers/dma-buf/reservation.c: In function 'reservation_object_add_shared_fence':
/kisskb/src/drivers/dma-buf/reservation.c:207:2: warning: 'k' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/drivers/dma-buf/reservation.c:160:17: note: 'k' was declared here
/kisskb/src/mm/hugetlb.c: In function 'alloc_pool_huge_page':
/kisskb/src/mm/hugetlb.c:1433:5: warning: 'page' may be used uninitialized in this function [-Wuninitialized]
No errors detected in 21106 functions.
  Kernel: vmlinux.gz is ready
Completed OK
# rm -rf /kisskb/build/powerpc-fixes_ia64-defconfig_ia64
# Build took: 0:02:00.144221