On 2013-02-24 11:11, Avi Kivity wrote: > On Sun, Feb 24, 2013 at 11:40 AM, Jan Kiszka <jan.kiszka@xxxxxx> wrote: >>>>> We have the same problem in KVM_SET_SREGS. >>>> >>>> I don't see the problem. kvm_arch_vcpu_ioctl_set_sregs open-codes the >>>> state update, not applying any transition checks. >>> >>> That's the problem. We have this open coding in three different >>> places (KVM_SET_SREGS, nvmx, nsvm). >>> >>> It's not as if vmx_set_cr0() is defined as "kvm_set_cr0() without the >>> transition checks". >> >> ...and without mmu updates. The latter is done via or after the closing >> cr3 update. Interestingly, nsvm does not perform kvm_set_cr3 on vmexit >> when in npt mode. Seems things aren't that regular. > > We do want the mmu updates. Of course they can't be attached to > kvm_set_cr0_without_the_checks() since there is cross-register > dependencies. > > Option 1 is kvm_set_multiple_cr(). This does the checks and updates, > but only after all registers are updated. > Option 2 is kvm_begin_cr_transaction()/kvm_commit_cr_transaction(). > Prettier and more flexible, but a more complicated to implement. > The only thing that these three use case truly have in common is the closing kvm_mmu_reset_context. Maybe nvmx and nsvm can share a bit more. But let's get nVMX right first, then think about sharing. Jan
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