> diff --git a/target/s390x/mem_helper.c b/target/s390x/mem_helper.c
> index f6e5bce..de0ecd4 100644
> --- a/target/s390x/mem_helper.c
> +++ b/target/s390x/mem_helper.c
> @@ -20,6 +20,7 @@
>
> #include "qemu/osdep.h"
> #include "cpu.h"
> +#include "exec/address-spaces.h"
> #include "exec/helper-proto.h"
> #include "exec/exec-all.h"
> #include "exec/cpu_ldst.h"
> @@ -973,6 +974,33 @@ void HELPER(stctl)(CPUS390XState *env, uint32_t r1,
> uint64_t a2, uint32_t r3)
> }
> }
>
> +uint32_t HELPER(testblock)(CPUS390XState *env, uint64_t real_addr)
> +{
> + CPUState *cs = CPU(s390_env_get_cpu(env));
> + uint64_t abs_addr;
> + int i;
> +
It is somewhat strange that we set a condition code in case of a program
interrupt (I assume that's the magic of the return value?). But maybe
setting the CC on program interrupts is perfectly valid.
Reading the PoP, I think it is supposed to be like this:
- Memory not addressable? -> PGM_ADDRESSING
- Memory protected? -> PGM_PROTECTION
- Memory not usable ("invalid checking-block-code", using it would
result in a machine check) -> CC=1
- Memory usable and cleared -> CC=0
So in essence, I think we should only set the CC if successful, as we
are not simulating ram failure. But maybe that's how all these handlers
work, and we can't hinder it from setting the CC.
> + real_addr = fix_address(env, real_addr);
Could it be that fix_address() misses handling for 24 bit mode? (no idea
if that is really relevant, just wondering).
> + abs_addr = mmu_real2abs(env, real_addr) & TARGET_PAGE_MASK;
> + if (!address_space_access_valid(&address_space_memory, abs_addr,
> + TARGET_PAGE_SIZE, true)) {
> + program_interrupt(env, PGM_ADDRESSING, 4);
> + return 1;
> + }
> +
> + /* Check low-address protection */
> + if ((env->cregs[0] & CR0_LOWPROT) != 0 && real_addr < 0x2000) {
I would drop the != 0.
> + program_interrupt(env, PGM_PROTECTION, 4);
> + return 1;
> + }
> +
> + for (i = 0; i < TARGET_PAGE_SIZE; i += 8) {
> + stq_phys(cs->as, abs_addr + i, 0);
> + }
> +
> + return 0;
> +}
Looks good to me!
--
Thanks,
David
