Currently kvmtool uses rewinds (lseeks to position 0) on kernel image files. This prevents non-regular files (for instance pipes in the -k parameter) from being used as a kernel image file.
This series reworks the kernel loading to avoid any seeks and allows to pipe in kernel images on the command line. This basically gives us decompression and direct kernel downloading for free in a neat UNIX way: $ lkvm run -k <(zcat zImage.gz) ... $ lkvm run -k <(dd if=uImage bs=64 skip=1) ... $ lkvm run -k <(wget -O - http://foo.com/guest.zImage) ... $ lkvm run -k <(curl -s tftp://server/guest.zImage) ... The first patch refactors the kernel image loading, which currently tries to be architecture agnostic in a very intricate way. As the actual implementations are very much architecture specific, make this clear in the code by introducing separate functions for each arch. Allowing pipes is quite easy for arm/arm64 and powerpc, since they only do a (now pointless) rewind in the beginning, which we simply drop in patch 2. x86 requires some more love, patch 3 and 4 take care of that for bzImage and "flat binaries", respectively. Since the MIPS ELF loader contains an actual (non-rewinding) seek, patch 5 adds a pipe-aware wrapper around lseek to still do some (forward) seeking despite the file descriptor being non-seekable. Patch 6, 7 and 8 then use this to eventually rework the kernel image loading for MIPS to be pipe-safe, too. Patch 9 moves the ARM kernel loading from arm/fdt.c into arm/kvm.c, to be in line with the other architectures. Now that we may read from pipes or sockets, simply using the read(2) syscall breaks occasionally. Patch 10 introduces a safe wrapper for reading whole files (inspired by the ARM implementation), whereas patches 11-14 move the kernel loading in each architecture over to using the safe read wrappers. These patches apply on top of the latest kvmtool master branch. So far I could test arm, arm64 and x86, with MIPS and PowerPC being at least compile-tested. Cheers, Andre. Andre Przywara (14): Refactor kernel image loading arm/powerpc: remove unneeded seeks in kernel loading x86: allow pipes for bzImage kernel images x86: support loading flat binary kernel images from a pipe kvmtool: introduce pseek MIPS: use pseek() in ELF kernel image loading MIPS: move ELF headers loading outside of load_elf_binary() MIPS: remove seeks from load_flat_binary() arm: move kernel loading into arm/kvm.c provide generic read_file() implementation arm/arm64: use read_file() in kernel and initrd loading powerpc: use read_file() in kernel and initrd loading MIPS: use read wrappers in kernel loading x86: use read wrappers in kernel loading arm/fdt.c | 99 +--------------------------------------- arm/kvm.c | 87 ++++++++++++++++++++++++++++++++++++ include/kvm/kvm.h | 5 +-- include/kvm/read-write.h | 4 ++ kvm.c | 42 ++--------------- mips/kvm.c | 114 ++++++++++++++++++++++++++--------------------- powerpc/kvm.c | 42 ++++++++--------- util/read-write.c | 61 +++++++++++++++++++++++++ x86/kvm.c | 102 ++++++++++++++++++++++-------------------- 9 files changed, 297 insertions(+), 259 deletions(-) -- 2.3.5 -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
