Re: [PATCH v9 11/15] s390x: protvirt: Disable address checks for PV guest IO emulation

[Claudio Imbrenda <imbrenda@linux.ibm.com>]

On Wed, 11 Mar 2020 09:21:47 -0400
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>
> Reviewed-by: Thomas Huth <thuth@redhat.com>
> Reviewed-by: David Hildenbrand <david@redhat.com>
> ---
>  target/s390x/ioinst.c | 33 ++++++++++++++++++++++++++-------
>  1 file changed, 26 insertions(+), 7 deletions(-)
> 
> diff --git a/target/s390x/ioinst.c b/target/s390x/ioinst.c
> index c437a1d8c6afed80..481d789de9e09a04 100644
> --- a/target/s390x/ioinst.c
> +++ b/target/s390x/ioinst.c
> @@ -16,6 +16,23 @@
>  #include "hw/s390x/ioinst.h"
>  #include "trace.h"
>  #include "hw/s390x/s390-pci-bus.h"
> +#include "hw/s390x/pv.h"
> +
> +static uint64_t get_address_from_regs(CPUS390XState *env, uint32_t
> ipb,
> +                                      uint8_t *ar)
> +{
> +    /*
> +     * Addresses for protected guests are all offsets into the
> +     * satellite block which holds the IO control structures. Those
> +     * control structures are always aligned and accessible, so we
> can
> +     * return 0 here which will pass the following address checks.
> +     */
> +    if (s390_is_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)
> @@ -114,7 +131,7 @@ void ioinst_handle_msch(S390CPU *cpu, uint64_t
> reg1, uint32_t ipb, uintptr_t ra) CPUS390XState *env = &cpu->env;
>      uint8_t ar;
>  
> -    addr = decode_basedisp_s(env, ipb, &ar);
> +    addr = get_address_from_regs(env, ipb, &ar);
>      if (addr & 3) {
>          s390_program_interrupt(env, PGM_SPECIFICATION, ra);
>          return;
> @@ -171,7 +188,7 @@ void ioinst_handle_ssch(S390CPU *cpu, uint64_t
> reg1, uint32_t ipb, uintptr_t ra) CPUS390XState *env = &cpu->env;
>      uint8_t ar;
>  
> -    addr = decode_basedisp_s(env, ipb, &ar);
> +    addr = get_address_from_regs(env, ipb, &ar);
>      if (addr & 3) {
>          s390_program_interrupt(env, PGM_SPECIFICATION, ra);
>          return;
> @@ -203,7 +220,7 @@ void ioinst_handle_stcrw(S390CPU *cpu, uint32_t
> ipb, uintptr_t ra) CPUS390XState *env = &cpu->env;
>      uint8_t ar;
>  
> -    addr = decode_basedisp_s(env, ipb, &ar);
> +    addr = get_address_from_regs(env, ipb, &ar);
>      if (addr & 3) {
>          s390_program_interrupt(env, PGM_SPECIFICATION, ra);
>          return;
> @@ -234,7 +251,7 @@ void ioinst_handle_stsch(S390CPU *cpu, uint64_t
> reg1, uint32_t ipb, CPUS390XState *env = &cpu->env;
>      uint8_t ar;
>  
> -    addr = decode_basedisp_s(env, ipb, &ar);
> +    addr = get_address_from_regs(env, ipb, &ar);
>      if (addr & 3) {
>          s390_program_interrupt(env, PGM_SPECIFICATION, ra);
>          return;
> @@ -303,7 +320,7 @@ int ioinst_handle_tsch(S390CPU *cpu, uint64_t
> reg1, uint32_t ipb, uintptr_t ra) return -EIO;
>      }
>      trace_ioinst_sch_id("tsch", cssid, ssid, schid);
> -    addr = decode_basedisp_s(env, ipb, &ar);
> +    addr = get_address_from_regs(env, ipb, &ar);
>      if (addr & 3) {
>          s390_program_interrupt(env, PGM_SPECIFICATION, ra);
>          return -EIO;
> @@ -601,7 +618,7 @@ 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 +627,9 @@ void ioinst_handle_chsc(S390CPU *cpu, uint32_t
> ipb, uintptr_t ra) 
>      trace_ioinst("chsc");
>      reg = (ipb >> 20) & 0x00f;
> -    addr = env->regs[reg];
> +    if (!s390_is_pv()) {
> +        addr = env->regs[reg];
> +    }
>      /* Page boundary? */
>      if (addr & 0xfff) {
>          s390_program_interrupt(env, PGM_SPECIFICATION, ra);

Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>