On 10.01.2013, at 16:28, Jason J. Herne wrote: > Rework the method used to synchronize CPU registers between Qemu & > KVM. This patch set extends kvm_arch_put_registers() and > kvm_arch_get_registers() to take a register bitmap parameter. All > existing code paths are updated to specify this new parameter. > > IMPORTANT NOTE: The PPC and i386 implementations are incomplete. > I am submitting this code at this time only to get a review on the > implementation of the existing code and to perhaps seek assistance > with the mentioned architectures. > > I am not sure who will finish the implementation of PPC/i386 yet. Due > to the fact that I am unfamiliar with these architectures at the > register level and I do not have test environments I would like to > humbly request that a maintainer of these architectures take a look at > it. Or perhaps Bharat could handle the PPC code? This would only leave i386 > to worry about. If I cannot find someone to handle i386 I > will look into the feasibility of completing it myself. > > In order to complete the missing implementations, > kvm_arch_get_registers and kvm_arch_put_registers (and associated > helper functions) will need to be updated to only sync the registers > contained in the new bitmap argument.
I disagree. The read functions would stay the way they are, because they always read everything today. The write functions would read bitmap bits instead of "level < x". The bitmap would contain bits for LEVEL_1 LEVEL_2 LEVEL_3 with the externally used LEVEL_3 define that you would use for syncing being (LEVEL_1 | LEVEL_2 | LEVEL_3). That way you keep the level based semantic and nobody really needs non-obvious code changes. > Also, each set of registers > represented by one of the bits must be mutually exclusive with respect > to every other bit. if this is not the case then local register data > can be lost when kvm_arch_get_registers is called causing an old > register value to overwrite a newer local value. Any get_registers call with a changing bitmap would flush out everything and start from scratch. Don't overoptimize from the beginning :). Alex
