That sounds good to me.
Thanks!
--jim
On Fri, Mar 3, 2017 at 8:12 AM, Radim Krčmář <rkrcmar@xxxxxxxxxx> wrote:
> 2017-03-02 12:41-0800, Jim Mattson:
>> VMCLEAR should silently ignore a failure to clear the launch state of
>> the VMCS referenced by the operand.
>>
>> Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx>
>> ---
>> arch/x86/kvm/vmx.c | 22 ++++------------------
>> 1 file changed, 4 insertions(+), 18 deletions(-)
>>
>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
>> index ef4ba71dbb66..bca497a92541 100644
>> --- a/arch/x86/kvm/vmx.c
>> +++ b/arch/x86/kvm/vmx.c
>> @@ -7259,9 +7259,8 @@ static int handle_vmoff(struct kvm_vcpu *vcpu)
>> static int handle_vmclear(struct kvm_vcpu *vcpu)
>> {
>> struct vcpu_vmx *vmx = to_vmx(vcpu);
>> + u32 zero = 0;
>> gpa_t vmptr;
>> - struct vmcs12 *vmcs12;
>> - struct page *page;
>>
>> if (!nested_vmx_check_permission(vcpu))
>> return 1;
>> @@ -7272,22 +7271,9 @@ static int handle_vmclear(struct kvm_vcpu *vcpu)
>> if (vmptr == vmx->nested.current_vmptr)
>> nested_release_vmcs12(vmx);
>>
>> - page = nested_get_page(vcpu, vmptr);
>> - if (page == NULL) {
>> - /*
>> - * For accurate processor emulation, VMCLEAR beyond available
>> - * physical memory should do nothing at all. However, it is
>> - * possible that a nested vmx bug, not a guest hypervisor bug,
>> - * resulted in this case, so let's shut down before doing any
>> - * more damage:
>> - */
>
> (Consciously introducing bugs in order to somewhat mitigate possible
> bugs is not desirable.)
>
>> - kvm_make_request(KVM_REQ_TRIPLE_FAULT, vcpu);
>> - return 1;
>> - }
>> - vmcs12 = kmap(page);
>> - vmcs12->launch_state = 0;
>> - kunmap(page);
>> - nested_release_page(page);
>> + kvm_write_guest(vcpu->kvm,
>
> I have changed this line to
>
> kvm_vcpu_write_guest(vcpu
>
> and applied to kvm/queue (planning to merge in 4.11-rc2).
>
> The change makes a difference if the guest is using VMX inside SMM and I
> don't see a reason to avoid the SMM address space in that case.
> Let me know what you think,
>
> thanks.
>
>> + vmptr + offsetof(struct vmcs12, launch_state),
>> + &zero, sizeof(zero));
>
> (Could have also been kvm_vcpu_write_guest_page(), but that is only
> performance gain.)
>
>>
>> nested_free_vmcs02(vmx, vmptr);
>>
>> --
>> 2.12.0.rc1.440.g5b76565f74-goog
>>
