The kvm_call_hyp calling convention and semantics should be described. Also, just in case someone looks at the return value from __kvm_vcpu_run without casting it to an unsigned long, we clear the upper bits. Signed-off-by: Christoffer Dall <c.dall@xxxxxxxxxxxxxxxxxxxxxx> --- arch/arm/kvm/interrupts.S | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/arch/arm/kvm/interrupts.S b/arch/arm/kvm/interrupts.S index f07ba92..c33a0f5 100644 --- a/arch/arm/kvm/interrupts.S +++ b/arch/arm/kvm/interrupts.S @@ -196,9 +196,32 @@ after_vfp_restore: restore_host_regs clrex @ Clear exclusive monitor mov r0, r1 @ Return the return code + mov r1, #0 @ Clear upper bits in return value bx lr @ return to IOCTL +/******************************************************************** + * Call function in Hyp mode + * + * + * u64 kvm_call_hyp(void *hypfn, ...); + * + * This is not really a variadic function in the classic C-way and care must + * be taken when calling this to ensure parameters are passed in registers + * only, since the stack will change between the caller and the callee. + * + * Call the function with the first argument containing a pointer to the + * function you wish to call in Hyp mode, and subsequent arguments will be + * passed as r0, r1, and r2 (a maximum of 3 arguments in addition to the + * function pointer can be passed). The function being called must be mapped + * in Hyp mode (see init_hyp_mode in arch/arm/kvm/arm.c). Return values are + * passed in r0 and r1. + * + * The calling convention follows the standard AAPCS: + * r0 - r3: caller save + * r12: caller save + * rest: callee save + */ ENTRY(kvm_call_hyp) hvc #0 bx lr -- 1.7.9.5 _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/cucslists/listinfo/kvmarm
