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SubjectRe: [RFC 05/12] KVM/VMX: Use the new host mapping API for mapping nested vmptr
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On 02/05/2018 11:15 PM, Jim Mattson wrote:
> On Mon, Feb 5, 2018 at 10:49 AM KarimAllah Ahmed <karahmed@amazon.de> wrote:
>
>
>> @@ -7410,19 +7410,17 @@ static int handle_vmon(struct kvm_vcpu *vcpu)
>> return kvm_skip_emulated_instruction(vcpu);
>> }
>
>> - page = kvm_vcpu_gpa_to_page(vcpu, vmptr);
>> - if (is_error_page(page)) {
>> + if (!kvm_vcpu_gpa_to_host_mapping(vcpu, vmptr, &mapping, true)) {
>> nested_vmx_failInvalid(vcpu);
>> return kvm_skip_emulated_instruction(vcpu);
>> }
>> - if (*(u32 *)kmap(page) != VMCS12_REVISION) {
>> - kunmap(page);
>> - kvm_release_page_clean(page);
>> + if (*(u32 *)mapping.kaddr != VMCS12_REVISION) {
>> + kvm_release_host_mapping(&mapping, false);
>> nested_vmx_failInvalid(vcpu);
>> return kvm_skip_emulated_instruction(vcpu);
>> }
>> - kunmap(page);
>> - kvm_release_page_clean(page);
>> +
>> + kvm_release_host_mapping(&mapping, false);
>
> Why go through this explicit mapping/release dance? Why not just:
>
> uint32_t revision;
> ...
> if (kvm_read_guest(vcpu->kvm, vmptr, &revision, sizeof(revision)) ||
> revision != VMCS12_REVISION) {
> nested_vmx_failInvalid(vcpu);
> return kvm_skip_emulated_instruction(vcpu);
> }
>

Fair enough, I will update.
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