On 30/07/19 10:48, Paolo Bonzini wrote: > On 29/07/19 13:56, Anup Patel wrote: >> + cntx->hstatus |= HSTATUS_SP2V; >> + cntx->hstatus |= HSTATUS_SP2P; > IIUC, cntx->hstatus's SP2P bit contains the guest's sstatus.SPP bit?
Nevermind, that was also a bit confused. The guest's sstatus.SPP is in vsstatus. The pseudocode for V-mode switch is SRET: V = hstatus.SPV (1) MODE = sstatus.SPP hstatus.SPV = hstatus.SP2V sstatus.SPP = hstatus.SP2P hstatus.SP2V = 0 hstatus.SP2P = 0 ... trap: hstatus.SP2V = hstatus.SPV hstatus.SP2P = sstatus.SPP hstatus.SPV = V (1) sstatus.SPP = MODE V = 0 MODE = 1 so: 1) indeed we need SP2V=SPV=1 when entering guest mode 2) sstatus.SPP contains the guest mode 3) SP2P doesn't really matter for KVM since it never goes to VS-mode from an interrupt handler, so if my reasoning is correct I'd leave it clear, but I guess it's up to you whether to set it or not. Paolo > I suggest adding a comment here, and again providing a ONE_REG interface > to sstatus so that the ABI is final before RISC-V KVM is merged. > > What happens if the guest executes SRET? Is that EXC_SYSCALL in hedeleg? > > (BTW the name of SP2V and SP2P is horrible, I think HPV/HPP or HSPV/HSPP > would have been clearer, but that's not your fault).
