On 06/07/2018 18:13, Thomas Gleixner wrote: > To allow early utilization of kvmclock it is required to remove the > memblock dependency. memblock is currently used to allocate the per > cpu data for kvmclock. > > The first patch replaces the memblock with a static array sized 64bytes * > NR_CPUS and was posted by Pavel. That patch allocates everything statically > which is a waste when kvmclock is not used. > > The rest of the series cleans up the code and converts it to per cpu > variables but does not put the kvmclock data into the per cpu area as that > has an issue vs. mapping the boot cpu data into the VDSO (leaks arbitrary > data, unless page sized). > > The per cpu data consists of pointers to the actual data. For the boot cpu > a page sized array is statically allocated which can be mapped into the > VDSO. That array is used for initializing the first 64 CPU pointers. If > there are more CPUs the pvclock data is allocated during CPU bringup. > > So this still will have some overhead when kvmclock is not in use, but > bringing it down to zero would be a massive trainwreck and even more > indirections. > > Thanks, > > tglx > > 8<-------------- > a/arch/x86/include/asm/kvm_guest.h | 7 > arch/x86/include/asm/kvm_para.h | 1 > arch/x86/kernel/kvm.c | 14 - > arch/x86/kernel/kvmclock.c | 262 ++++++++++++++----------------------- > arch/x86/kernel/setup.c | 4 > 5 files changed, 105 insertions(+), 183 deletions(-) > > > > Thanks, this is really nice. With the small changes from my review, Acked-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> Paolo
