# git rev-parse -q --verify d99d49613b7cd196ea161fc708040ea88adb6e18^{commit}
d99d49613b7cd196ea161fc708040ea88adb6e18
already have revision, skipping fetch
# git checkout -q -f -B kisskb d99d49613b7cd196ea161fc708040ea88adb6e18
# git clean -qxdf
# < git log -1
# commit d99d49613b7cd196ea161fc708040ea88adb6e18
# Author: Alexey Kardashevskiy <aik@ozlabs.ru>
# Date:   Wed Jul 4 15:00:52 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 only allows huge pages use if the entire
#     preregistered block is backed with huge pages which are completely
#     contained the preregistered chunk; otherwise this defaults to PAGE_SIZE.
#     
#     Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
#     Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
# < /opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux-gcc --version
# < git log --format=%s --max-count=1 d99d49613b7cd196ea161fc708040ea88adb6e18
# < make -s -j 120 ARCH=powerpc O=/kisskb/build/powerpc-fixes_mpc885_ads_defconfig+HUGETLB_powerpc CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux-  mpc885_ads_defconfig
# Added to kconfig CONFIG_HUGETLBFS=y
# yes \n | make -s -j 120 ARCH=powerpc O=/kisskb/build/powerpc-fixes_mpc885_ads_defconfig+HUGETLB_powerpc CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux-  oldconfig
yes: standard output: Broken pipe
yes: write error
# make -s -j 120 ARCH=powerpc O=/kisskb/build/powerpc-fixes_mpc885_ads_defconfig+HUGETLB_powerpc CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux-  
/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/net/Makefile:24: CC cannot link executables. Skipping bpfilter.
/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/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]
Image Name:   Linux-4.18.0-rc3-gd99d496
Created:      Thu Jul  5 00:38:32 2018
Image Type:   PowerPC Linux Kernel Image (gzip compressed)
Data Size:    1787231 Bytes = 1745.34 kB = 1.70 MB
Load Address: 00400000
Entry Point:  004001a4
Completed OK
# rm -rf /kisskb/build/powerpc-fixes_mpc885_ads_defconfig+HUGETLB_powerpc
# Build took: 0:00:19.341724