On Wed, Nov 13, 2019 at 11:14:27AM +1100, Paul Mackerras wrote:
On Tue, Nov 12, 2019 at 06:45:55AM -0800, Ram Pai wrote:
quoted
On Tue, Nov 12, 2019 at 10:32:04PM +1100, Paul Mackerras wrote:
quoted
On Mon, Nov 11, 2019 at 11:52:15PM -0800, Ram Pai wrote:
quoted
There is subtle problem removing that code from the assembly.
If the H_SVM_INIT_ABORT hcall returns to the ultravisor without clearing
kvm->arch.secure_guest, the hypervisor will continue to think that the
VM is a secure VM. However the primary reason the H_SVM_INIT_ABORT
hcall was invoked, was to inform the Hypervisor that it should no longer
consider the VM as a Secure VM. So there is a inconsistency there.
Most of the checks that look at whether a VM is a secure VM use code
like "if (kvm->arch.secure_guest & KVMPPC_SECURE_INIT_DONE)". Now
since KVMPPC_SECURE_INIT_ABORT is 4, an if statement such as that will
take the false branch once we have set kvm->arch.secure_guest to
KVMPPC_SECURE_INIT_ABORT in kvmppc_h_svm_init_abort. So in fact in
most places we will treat the VM as a normal VM from then on. If
there are any places where we still need to treat the VM as a secure
VM while we are processing the abort we can easily do that too.
Is the suggestion -- KVMPPC_SECURE_INIT_ABORT should never return back
to the Ultravisor? Because removing that assembly code will NOT lead the
No. The suggestion is that vcpu->arch.secure_guest stays set to
KVMPPC_SECURE_INIT_ABORT until userspace calls KVM_PPC_SVM_OFF.
In the fast_guest_return path, if it finds
(kvm->arch.secure_guest & KVMPPC_SECURE_INIT_ABORT) is true, should it return to
UV or not?
Ideally it should return back to the ultravisor the first time
KVMPPC_SECURE_INIT_ABORT is set, and not than onwards.
RP