[PATCH v2] target/s390x/tcg: SPX: check validity of new prefix

[PATCH v2] target/s390x/tcg: SPX: check validity of new prefix

[Janis Schoetterl-Glausch]

According to the architecture, SET PREFIX must try to access the new
prefix area and recognize an addressing exception if the area is not
accessible.
For qemu this check prevents a crash in cpu_map_lowcore after an
inaccessible prefix area has been set.

Signed-off-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
---
 target/s390x/tcg/misc_helper.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/target/s390x/tcg/misc_helper.c b/target/s390x/tcg/misc_helper.c
index aab9c47747..10dadb002a 100644
--- a/target/s390x/tcg/misc_helper.c
+++ b/target/s390x/tcg/misc_helper.c
@@ -158,6 +158,13 @@ void HELPER(spx)(CPUS390XState *env, uint64_t a1)
     if (prefix == old_prefix) {
         return;
     }
+    /*
+     * Since prefix got aligned to 8k and memory increments are a multiple of
+     * 8k checking the first page is sufficient
+     */
+    if (!mmu_absolute_addr_valid(prefix, true)) {
+        tcg_s390_program_interrupt(env, PGM_ADDRESSING, GETPC());
+    }
 
     env->psa = prefix;
     HELPER_LOG("prefix: %#x\n", prefix);

base-commit: 3a821c52e1a30ecd9a436f2c67cc66b5628c829f
-- 
2.36.1

Re: [PATCH v2] target/s390x/tcg: SPX: check validity of new prefix

[Thomas Huth]

On 30/06/2022 11.43, Janis Schoetterl-Glausch wrote:
> According to the architecture, SET PREFIX must try to access the new
> prefix area and recognize an addressing exception if the area is not
> accessible.
> For qemu this check prevents a crash in cpu_map_lowcore after an
> inaccessible prefix area has been set.
> 
> Signed-off-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
> Reviewed-by: David Hildenbrand <david@redhat.com>
> ---
>   target/s390x/tcg/misc_helper.c | 7 +++++++
>   1 file changed, 7 insertions(+)
> 
> diff --git a/target/s390x/tcg/misc_helper.c b/target/s390x/tcg/misc_helper.c
> index aab9c47747..10dadb002a 100644
> --- a/target/s390x/tcg/misc_helper.c
> +++ b/target/s390x/tcg/misc_helper.c
> @@ -158,6 +158,13 @@ void HELPER(spx)(CPUS390XState *env, uint64_t a1)
>       if (prefix == old_prefix) {
>           return;
>       }
> +    /*
> +     * Since prefix got aligned to 8k and memory increments are a multiple of
> +     * 8k checking the first page is sufficient
> +     */
> +    if (!mmu_absolute_addr_valid(prefix, true)) {
> +        tcg_s390_program_interrupt(env, PGM_ADDRESSING, GETPC());
> +    }
>   
>       env->psa = prefix;
>       HELPER_LOG("prefix: %#x\n", prefix);

Thanks, queued to my s390x-next branch now:

  https://gitlab.com/thuth/qemu/-/commits/s390x-next

  Thomas