Re: [PATCH v2 12/13] s390x: protvirt: Disable address checks for PV guest IO emulation

[Cornelia Huck <cohuck@redhat.com>]

On Fri, 29 Nov 2019 04:48:08 -0500
Janosch Frank <frankja@linux.ibm.com> wrote:

> IO instruction data is routed through SIDAD for protected guests, so
> adresses do not need to be checked, as this is kernel memory.
> 
> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
> ---
>  target/s390x/ioinst.c | 26 +++++++++++++++++++-------
>  1 file changed, 19 insertions(+), 7 deletions(-)
> 
> diff --git a/target/s390x/ioinst.c b/target/s390x/ioinst.c
> index c437a1d8c6..e4102430aa 100644
> --- a/target/s390x/ioinst.c
> +++ b/target/s390x/ioinst.c
> @@ -17,6 +17,16 @@
>  #include "trace.h"
>  #include "hw/s390x/s390-pci-bus.h"
>  
> +static uint64_t get_address_from_regs(CPUS390XState *env, uint32_t ipb,
> +                                      uint8_t *ar)

Would like to keep the ioinst_* pattern here (even though this is an
internal function). ioinst_decode_addr()?

> +{
> +    if (env->pv) {
> +        *ar = 0;
> +        return 0;
> +    }
> +    return decode_basedisp_s(env, ipb, ar);
> +}
> +
>  int ioinst_disassemble_sch_ident(uint32_t value, int *m, int *cssid, int *ssid,
>                                   int *schid)
>  {

(...)

> @@ -601,7 +611,7 @@ void ioinst_handle_chsc(S390CPU *cpu, uint32_t ipb, uintptr_t ra)
>  {
>      ChscReq *req;
>      ChscResp *res;
> -    uint64_t addr;
> +    uint64_t addr = 0;
>      int reg;
>      uint16_t len;
>      uint16_t command;
> @@ -610,7 +620,9 @@ void ioinst_handle_chsc(S390CPU *cpu, uint32_t ipb, uintptr_t ra)
>  
>      trace_ioinst("chsc");
>      reg = (ipb >> 20) & 0x00f;
> -    addr = env->regs[reg];
> +    if (!env->pv) {
> +        addr = env->regs[reg];
> +    }

addr = env->pv ? 0 : env->regs[reg];

?

>      /* Page boundary? */
>      if (addr & 0xfff) {
>          s390_program_interrupt(env, PGM_SPECIFICATION, ra);