Messages in this thread | | | Date | Thu, 21 Jul 2022 15:34:59 +0800 | Subject | Re: [PATCH v7 11/14] KVM: Register/unregister the guest private memory regions | From | Wei Wang <> |
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On 7/21/22 00:21, Sean Christopherson wrote: > On Wed, Jul 20, 2022, Gupta, Pankaj wrote: >>>>>>> +bool __weak kvm_arch_private_mem_supported(struct kvm *kvm) > Use kvm_arch_has_private_mem(), both because "has" makes it obvious this is checking > a flag of sorts, and to align with other helpers of this nature (and with > CONFIG_HAVE_KVM_PRIVATE_MEM). > > $ git grep kvm_arch | grep supported | wc -l > 0 > $ git grep kvm_arch | grep has | wc -l > 26 > >>>>>>> +#ifdef CONFIG_HAVE_KVM_PRIVATE_MEM >>>>>>> + case KVM_MEMORY_ENCRYPT_REG_REGION: >>>>>>> + case KVM_MEMORY_ENCRYPT_UNREG_REGION: { >>>>>>> + struct kvm_enc_region region; >>>>>>> + >>>>>>> + if (!kvm_arch_private_mem_supported(kvm)) >>>>>>> + goto arch_vm_ioctl; >>>>>>> + >>>>>>> + r = -EFAULT; >>>>>>> + if (copy_from_user(®ion, argp, sizeof(region))) >>>>>>> + goto out; >>>>>>> + >>>>>>> + r = kvm_vm_ioctl_set_encrypted_region(kvm, ioctl, ®ion); >>>>>> this is to store private region metadata not only the encrypted region? >>>>> Correct. >>>> Sorry for not being clear, was suggesting name change of this function from: >>>> "kvm_vm_ioctl_set_encrypted_region" to "kvm_vm_ioctl_set_private_region" >>> Though I don't have strong reason to change it, I'm fine with this and >> Yes, no strong reason, just thought "kvm_vm_ioctl_set_private_region" would >> depict the actual functionality :) >> >>> this name matches the above kvm_arch_private_mem_supported perfectly. >> BTW could not understand this, how "kvm_vm_ioctl_set_encrypted_region" >> matches "kvm_arch_private_mem_supported"? > Chao is saying that kvm_vm_ioctl_set_private_region() pairs nicely with > kvm_arch_private_mem_supported(), not that the "encrypted" variant pairs nicely. > > I also like using "private" instead of "encrypted", though we should probably > find a different verb than "set", because calling "set_private" when making the > region shared is confusing. I'm struggling to come up with a good alternative > though. > > kvm_vm_ioctl_set_memory_region() is already taken by KVM_SET_USER_MEMORY_REGION, > and that also means that anything with "memory_region" in the name is bound to be > confusing. > > Hmm, and if we move away from "encrypted", it probably makes sense to pass in > addr+size instead of a kvm_enc_region. > > Maybe this? > > static int kvm_vm_ioctl_set_or_clear_mem_private(struct kvm *kvm, gpa_t gpa, > gpa_t size, bool set_private) > > and then: > > #ifdef CONFIG_HAVE_KVM_PRIVATE_MEM > case KVM_MEMORY_ENCRYPT_REG_REGION: > case KVM_MEMORY_ENCRYPT_UNREG_REGION: { > bool set = ioctl == KVM_MEMORY_ENCRYPT_REG_REGION; > struct kvm_enc_region region; > > if (!kvm_arch_private_mem_supported(kvm)) > goto arch_vm_ioctl; > > r = -EFAULT; > if (copy_from_user(®ion, argp, sizeof(region))) > goto out; > > r = kvm_vm_ioctl_set_or_clear_mem_private(kvm, region.addr, > region.size, set); > break; > } > #endif > > I don't love it, so if someone has a better idea... > Maybe you could tag it with cgs for all the confidential guest support related stuff: e.g. kvm_vm_ioctl_set_cgs_mem()
bool is_private = ioctl == KVM_MEMORY_ENCRYPT_REG_REGION; ... kvm_vm_ioctl_set_cgs_mem(, is_private)
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