# 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_85xx_ge_imp3a_defconfig_powerpc CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux-  85xx/ge_imp3a_defconfig
# make -s -j 120 ARCH=powerpc O=/kisskb/build/powerpc-fixes_85xx_ge_imp3a_defconfig_powerpc CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/powerpc-linux/bin/powerpc-linux-  
/kisskb/src/net/Makefile:24: CC cannot link executables. Skipping bpfilter.
/kisskb/src/kernel/rcu/srcutree.c: In function 'init_srcu_struct_fields':
/kisskb/src/kernel/rcu/srcutree.c:146:32: warning: 'levelspread[<U3780>]' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/kernel/rcu/srcutree.c:94:6: note: 'levelspread[<U3780>]' was declared here
/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/drivers/base/regmap/regmap.c: In function 'regmap_raw_read':
/kisskb/src/drivers/base/regmap/regmap.c:2497:6: warning: 'ret' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/drivers/base/regmap/regmap.c: In function '_regmap_raw_write':
/kisskb/src/drivers/base/regmap/regmap.c:1819:6: warning: 'ret' 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/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/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/drivers/tty/serial/8250/8250_core.c: In function 'univ8250_release_irq':
/kisskb/src/drivers/tty/serial/8250/8250_core.c:251:18: warning: 'i' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/drivers/tty/serial/8250/8250_core.c:231:19: note: 'i' was declared here
/kisskb/src/drivers/net/tun.c: In function 'tun_get_user':
/kisskb/src/drivers/net/tun.c:1835:30: warning: 'copylen' may be used uninitialized in this function [-Wuninitialized]
/kisskb/src/drivers/net/tun.c:1745:46: warning: 'linear' may be used uninitialized in this function [-Wuninitialized]
INFO: Uncompressed kernel (size 0x80be78) overlaps the address of the wrapper(0x400000)
INFO: Fixing the link_address of wrapper to (0x900000)
Image Name:   Linux-4.18.0-rc3-gd99d496
Created:      Thu Jul  5 00:00:12 2018
Image Type:   PowerPC Linux Kernel Image (gzip compressed)
Data Size:    4115685 Bytes = 4019.22 kB = 3.93 MB
Load Address: 00000000
Entry Point:  00000000
Completed OK
# rm -rf /kisskb/build/powerpc-fixes_85xx_ge_imp3a_defconfig_powerpc
# Build took: 0:00:21.950954