On Thu, Aug 22, 2019 at 12:48:38AM -0300, Claudio Carvalho wrote: > From: Sukadev Bhattiprolu <suka...@linux.vnet.ibm.com> > > When an SVM makes an hypercall or incurs some other exception, the > Ultravisor usually forwards (a.k.a. reflects) the exceptions to the > Hypervisor. After processing the exception, Hypervisor uses the > UV_RETURN ultracall to return control back to the SVM. > > The expected register state on entry to this ultracall is: > > * Non-volatile registers are restored to their original values. > * If returning from an hypercall, register R0 contains the return value > (unlike other ultracalls) and, registers R4 through R12 contain any > output values of the hypercall. > * R3 contains the ultracall number, i.e UV_RETURN. > * If returning with a synthesized interrupt, R2 contains the > synthesized interrupt number.
This isn't accurate: R2 contains the value that should end up in SRR1 when we are back in the secure guest. HSRR0 and HSRR1 contain the instruction pointer and MSR that the guest should run with. They may be different from the instruction pointer and MSR that the guest vCPU last had, if the hypervisor has synthesized an interrupt for the guest. The ultravisor needs to detect this case and respond appropriately. > Thanks to input from Paul Mackerras, Ram Pai and Mike Anderson. > > Signed-off-by: Sukadev Bhattiprolu <suka...@linux.vnet.ibm.com> > Signed-off-by: Claudio Carvalho <cclau...@linux.ibm.com> Apart from that comment on the patch description - Acked-by: Paul Mackerras <pau...@ozlabs.org>
