[PATCH] target/s390x: Implement the MVPG condition-code-option bit

Thomas Huth posted 1 patch 3 years, 2 months ago
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git fetch https://github.com/patchew-project/qemu tags/patchew/20210302191224.380963-1-thuth@redhat.com
Maintainers: Thomas Huth <thuth@redhat.com>, Richard Henderson <richard.henderson@linaro.org>, Cornelia Huck <cohuck@redhat.com>, David Hildenbrand <david@redhat.com>
There is a newer version of this series
target/s390x/cpu.h         | 14 ++++++++++++++
target/s390x/excp_helper.c | 14 --------------
target/s390x/mem_helper.c  | 23 ++++++++++++++++++++++-
3 files changed, 36 insertions(+), 15 deletions(-)
[PATCH] target/s390x: Implement the MVPG condition-code-option bit
Posted by Thomas Huth 3 years, 2 months ago
If the CCO bit is set, MVPG should not generate an exception
but report page translation faults via a CC code, so we have
to check the translation in this case before calling the
access_prepare() function.

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 This patch is required to get Claudio's new kvm-unit-tests patches
 working with TCG: https://www.spinics.net/lists/kvm/msg236784.html

 target/s390x/cpu.h         | 14 ++++++++++++++
 target/s390x/excp_helper.c | 14 --------------
 target/s390x/mem_helper.c  | 23 ++++++++++++++++++++++-
 3 files changed, 36 insertions(+), 15 deletions(-)

diff --git a/target/s390x/cpu.h b/target/s390x/cpu.h
index 60d434d5ed..731e2c6452 100644
--- a/target/s390x/cpu.h
+++ b/target/s390x/cpu.h
@@ -366,6 +366,20 @@ static inline int cpu_mmu_index(CPUS390XState *env, bool ifetch)
 #endif
 }
 
+static inline uint64_t cpu_mmu_idx_to_asc(int mmu_idx)
+{
+    switch (mmu_idx) {
+    case MMU_PRIMARY_IDX:
+        return PSW_ASC_PRIMARY;
+    case MMU_SECONDARY_IDX:
+        return PSW_ASC_SECONDARY;
+    case MMU_HOME_IDX:
+        return PSW_ASC_HOME;
+    default:
+        abort();
+    }
+}
+
 static inline void cpu_get_tb_cpu_state(CPUS390XState* env, target_ulong *pc,
                                         target_ulong *cs_base, uint32_t *flags)
 {
diff --git a/target/s390x/excp_helper.c b/target/s390x/excp_helper.c
index ce16af394b..44bff27f8f 100644
--- a/target/s390x/excp_helper.c
+++ b/target/s390x/excp_helper.c
@@ -105,20 +105,6 @@ bool s390_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
 
 #else /* !CONFIG_USER_ONLY */
 
-static inline uint64_t cpu_mmu_idx_to_asc(int mmu_idx)
-{
-    switch (mmu_idx) {
-    case MMU_PRIMARY_IDX:
-        return PSW_ASC_PRIMARY;
-    case MMU_SECONDARY_IDX:
-        return PSW_ASC_SECONDARY;
-    case MMU_HOME_IDX:
-        return PSW_ASC_HOME;
-    default:
-        abort();
-    }
-}
-
 bool s390_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
                        MMUAccessType access_type, int mmu_idx,
                        bool probe, uintptr_t retaddr)
diff --git a/target/s390x/mem_helper.c b/target/s390x/mem_helper.c
index 25cfede806..c7037adf2c 100644
--- a/target/s390x/mem_helper.c
+++ b/target/s390x/mem_helper.c
@@ -855,10 +855,31 @@ uint32_t HELPER(mvpg)(CPUS390XState *env, uint64_t r0, uint64_t r1, uint64_t r2)
     r1 = wrap_address(env, r1 & TARGET_PAGE_MASK);
     r2 = wrap_address(env, r2 & TARGET_PAGE_MASK);
 
+    /*
+     * If the condition-code-option (CCO) bit is set and DAT is enabled,
+     * we have to check for page table translation faults first:
+     */
+#ifndef CONFIG_USER_ONLY
+    if (extract64(r0, 8, 1) && mmu_idx != MMU_REAL_IDX) {
+        uint64_t asc = cpu_mmu_idx_to_asc(mmu_idx);
+        uint64_t raddr, tec;
+        int flags, exc;
+
+        exc = mmu_translate(env, r2, MMU_DATA_LOAD, asc, &raddr, &flags, &tec);
+        if (exc) {
+            return 2;
+        }
+
+        exc = mmu_translate(env, r1, MMU_DATA_STORE, asc, &raddr, &flags, &tec);
+        if (exc && exc != PGM_PROTECTION) {
+            return 1;
+        }
+    }
+#endif
+
     /*
      * TODO:
      * - Access key handling
-     * - CC-option with surpression of page-translation exceptions
      * - Store r1/r2 register identifiers at real location 162
      */
     srca = access_prepare(env, r2, TARGET_PAGE_SIZE, MMU_DATA_LOAD, mmu_idx,
-- 
2.27.0


Re: [PATCH] target/s390x: Implement the MVPG condition-code-option bit
Posted by David Hildenbrand 3 years, 2 months ago
On 02.03.21 20:12, Thomas Huth wrote:
> If the CCO bit is set, MVPG should not generate an exception
> but report page translation faults via a CC code, so we have
> to check the translation in this case before calling the
> access_prepare() function.
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>   This patch is required to get Claudio's new kvm-unit-tests patches
>   working with TCG: https://www.spinics.net/lists/kvm/msg236784.html
> 
>   target/s390x/cpu.h         | 14 ++++++++++++++
>   target/s390x/excp_helper.c | 14 --------------
>   target/s390x/mem_helper.c  | 23 ++++++++++++++++++++++-
>   3 files changed, 36 insertions(+), 15 deletions(-)
> 
> diff --git a/target/s390x/cpu.h b/target/s390x/cpu.h
> index 60d434d5ed..731e2c6452 100644
> --- a/target/s390x/cpu.h
> +++ b/target/s390x/cpu.h
> @@ -366,6 +366,20 @@ static inline int cpu_mmu_index(CPUS390XState *env, bool ifetch)
>   #endif
>   }
>   
> +static inline uint64_t cpu_mmu_idx_to_asc(int mmu_idx)
> +{
> +    switch (mmu_idx) {
> +    case MMU_PRIMARY_IDX:
> +        return PSW_ASC_PRIMARY;
> +    case MMU_SECONDARY_IDX:
> +        return PSW_ASC_SECONDARY;
> +    case MMU_HOME_IDX:
> +        return PSW_ASC_HOME;
> +    default:
> +        abort();
> +    }
> +}
> +
>   static inline void cpu_get_tb_cpu_state(CPUS390XState* env, target_ulong *pc,
>                                           target_ulong *cs_base, uint32_t *flags)
>   {
> diff --git a/target/s390x/excp_helper.c b/target/s390x/excp_helper.c
> index ce16af394b..44bff27f8f 100644
> --- a/target/s390x/excp_helper.c
> +++ b/target/s390x/excp_helper.c
> @@ -105,20 +105,6 @@ bool s390_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
>   
>   #else /* !CONFIG_USER_ONLY */
>   
> -static inline uint64_t cpu_mmu_idx_to_asc(int mmu_idx)
> -{
> -    switch (mmu_idx) {
> -    case MMU_PRIMARY_IDX:
> -        return PSW_ASC_PRIMARY;
> -    case MMU_SECONDARY_IDX:
> -        return PSW_ASC_SECONDARY;
> -    case MMU_HOME_IDX:
> -        return PSW_ASC_HOME;
> -    default:
> -        abort();
> -    }
> -}
> -
>   bool s390_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
>                          MMUAccessType access_type, int mmu_idx,
>                          bool probe, uintptr_t retaddr)
> diff --git a/target/s390x/mem_helper.c b/target/s390x/mem_helper.c
> index 25cfede806..c7037adf2c 100644
> --- a/target/s390x/mem_helper.c
> +++ b/target/s390x/mem_helper.c
> @@ -855,10 +855,31 @@ uint32_t HELPER(mvpg)(CPUS390XState *env, uint64_t r0, uint64_t r1, uint64_t r2)
>       r1 = wrap_address(env, r1 & TARGET_PAGE_MASK);
>       r2 = wrap_address(env, r2 & TARGET_PAGE_MASK);
>   
> +    /*
> +     * If the condition-code-option (CCO) bit is set and DAT is enabled,
> +     * we have to check for page table translation faults first:
> +     */
> +#ifndef CONFIG_USER_ONLY
> +    if (extract64(r0, 8, 1) && mmu_idx != MMU_REAL_IDX) {
> +        uint64_t asc = cpu_mmu_idx_to_asc(mmu_idx);
> +        uint64_t raddr, tec;
> +        int flags, exc;
> +
> +        exc = mmu_translate(env, r2, MMU_DATA_LOAD, asc, &raddr, &flags, &tec);
> +        if (exc) {
> +            return 2;
> +        }
> +
> +        exc = mmu_translate(env, r1, MMU_DATA_STORE, asc, &raddr, &flags, &tec);
> +        if (exc && exc != PGM_PROTECTION) {
> +            return 1;
> +        }
> +    }
> +#endif
> +

This way you always need two additional translations and don't even 
check if we have something in the TLB. While this works, it's quite 
inefficient.

Using probe_access_flags() we can actually lookup the tlb/fill the tlb 
but get an error instead of a fault. We could e.g., extent 
probe_access() to allow specifying whether we want a fault or not. If we 
then store the last exception during tlb_fill in a fixed location, we 
could obtain that information.


>       /*
>        * TODO:
>        * - Access key handling
> -     * - CC-option with surpression of page-translation exceptions
>        * - Store r1/r2 register identifiers at real location 162
>        */
>       srca = access_prepare(env, r2, TARGET_PAGE_SIZE, MMU_DATA_LOAD, mmu_idx,
> 


-- 
Thanks,

David / dhildenb


Re: [PATCH] target/s390x: Implement the MVPG condition-code-option bit
Posted by Richard Henderson 3 years, 2 months ago
On 3/2/21 11:25 AM, David Hildenbrand wrote:
> On 02.03.21 20:12, Thomas Huth wrote:
>> If the CCO bit is set, MVPG should not generate an exception
>> but report page translation faults via a CC code, so we have
>> to check the translation in this case before calling the
>> access_prepare() function.
>>
>> Signed-off-by: Thomas Huth <thuth@redhat.com>
>> ---
>>   This patch is required to get Claudio's new kvm-unit-tests patches
>>   working with TCG: https://www.spinics.net/lists/kvm/msg236784.html
>>
>>   target/s390x/cpu.h         | 14 ++++++++++++++
>>   target/s390x/excp_helper.c | 14 --------------
>>   target/s390x/mem_helper.c  | 23 ++++++++++++++++++++++-
>>   3 files changed, 36 insertions(+), 15 deletions(-)
>>
>> diff --git a/target/s390x/cpu.h b/target/s390x/cpu.h
>> index 60d434d5ed..731e2c6452 100644
>> --- a/target/s390x/cpu.h
>> +++ b/target/s390x/cpu.h
>> @@ -366,6 +366,20 @@ static inline int cpu_mmu_index(CPUS390XState *env, bool 
>> ifetch)
>>   #endif
>>   }
>> +static inline uint64_t cpu_mmu_idx_to_asc(int mmu_idx)
>> +{
>> +    switch (mmu_idx) {
>> +    case MMU_PRIMARY_IDX:
>> +        return PSW_ASC_PRIMARY;
>> +    case MMU_SECONDARY_IDX:
>> +        return PSW_ASC_SECONDARY;
>> +    case MMU_HOME_IDX:
>> +        return PSW_ASC_HOME;
>> +    default:
>> +        abort();
>> +    }
>> +}
>> +
>>   static inline void cpu_get_tb_cpu_state(CPUS390XState* env, target_ulong *pc,
>>                                           target_ulong *cs_base, uint32_t 
>> *flags)
>>   {
>> diff --git a/target/s390x/excp_helper.c b/target/s390x/excp_helper.c
>> index ce16af394b..44bff27f8f 100644
>> --- a/target/s390x/excp_helper.c
>> +++ b/target/s390x/excp_helper.c
>> @@ -105,20 +105,6 @@ bool s390_cpu_tlb_fill(CPUState *cs, vaddr address, int 
>> size,
>>   #else /* !CONFIG_USER_ONLY */
>> -static inline uint64_t cpu_mmu_idx_to_asc(int mmu_idx)
>> -{
>> -    switch (mmu_idx) {
>> -    case MMU_PRIMARY_IDX:
>> -        return PSW_ASC_PRIMARY;
>> -    case MMU_SECONDARY_IDX:
>> -        return PSW_ASC_SECONDARY;
>> -    case MMU_HOME_IDX:
>> -        return PSW_ASC_HOME;
>> -    default:
>> -        abort();
>> -    }
>> -}
>> -
>>   bool s390_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
>>                          MMUAccessType access_type, int mmu_idx,
>>                          bool probe, uintptr_t retaddr)
>> diff --git a/target/s390x/mem_helper.c b/target/s390x/mem_helper.c
>> index 25cfede806..c7037adf2c 100644
>> --- a/target/s390x/mem_helper.c
>> +++ b/target/s390x/mem_helper.c
>> @@ -855,10 +855,31 @@ uint32_t HELPER(mvpg)(CPUS390XState *env, uint64_t r0, 
>> uint64_t r1, uint64_t r2)
>>       r1 = wrap_address(env, r1 & TARGET_PAGE_MASK);
>>       r2 = wrap_address(env, r2 & TARGET_PAGE_MASK);
>> +    /*
>> +     * If the condition-code-option (CCO) bit is set and DAT is enabled,
>> +     * we have to check for page table translation faults first:
>> +     */
>> +#ifndef CONFIG_USER_ONLY
>> +    if (extract64(r0, 8, 1) && mmu_idx != MMU_REAL_IDX) {
>> +        uint64_t asc = cpu_mmu_idx_to_asc(mmu_idx);
>> +        uint64_t raddr, tec;
>> +        int flags, exc;
>> +
>> +        exc = mmu_translate(env, r2, MMU_DATA_LOAD, asc, &raddr, &flags, &tec);
>> +        if (exc) {
>> +            return 2;
>> +        }
>> +
>> +        exc = mmu_translate(env, r1, MMU_DATA_STORE, asc, &raddr, &flags, 
>> &tec);
>> +        if (exc && exc != PGM_PROTECTION) {
>> +            return 1;
>> +        }
>> +    }
>> +#endif
>> +
> 
> This way you always need two additional translations and don't even check if we 
> have something in the TLB. While this works, it's quite inefficient.
> 
> Using probe_access_flags() we can actually lookup the tlb/fill the tlb but get 
> an error instead of a fault. We could e.g., extent probe_access() to allow 
> specifying whether we want a fault or not.

I think probe_access_flags() will do all that you need; no further extension to 
probe_access() required.  I presume you meant access_prepare() is what you 
meant to extend?


r~

Re: [PATCH] target/s390x: Implement the MVPG condition-code-option bit
Posted by David Hildenbrand 3 years, 2 months ago
> Am 02.03.2021 um 22:46 schrieb Richard Henderson <richard.henderson@linaro.org>:
> 
> On 3/2/21 11:25 AM, David Hildenbrand wrote:
>>> On 02.03.21 20:12, Thomas Huth wrote:
>>> If the CCO bit is set, MVPG should not generate an exception
>>> but report page translation faults via a CC code, so we have
>>> to check the translation in this case before calling the
>>> access_prepare() function.
>>> 
>>> Signed-off-by: Thomas Huth <thuth@redhat.com>
>>> ---
>>>   This patch is required to get Claudio's new kvm-unit-tests patches
>>>   working with TCG: https://www.spinics.net/lists/kvm/msg236784.html
>>> 
>>>   target/s390x/cpu.h         | 14 ++++++++++++++
>>>   target/s390x/excp_helper.c | 14 --------------
>>>   target/s390x/mem_helper.c  | 23 ++++++++++++++++++++++-
>>>   3 files changed, 36 insertions(+), 15 deletions(-)
>>> 
>>> diff --git a/target/s390x/cpu.h b/target/s390x/cpu.h
>>> index 60d434d5ed..731e2c6452 100644
>>> --- a/target/s390x/cpu.h
>>> +++ b/target/s390x/cpu.h
>>> @@ -366,6 +366,20 @@ static inline int cpu_mmu_index(CPUS390XState *env, bool ifetch)
>>>   #endif
>>>   }
>>> +static inline uint64_t cpu_mmu_idx_to_asc(int mmu_idx)
>>> +{
>>> +    switch (mmu_idx) {
>>> +    case MMU_PRIMARY_IDX:
>>> +        return PSW_ASC_PRIMARY;
>>> +    case MMU_SECONDARY_IDX:
>>> +        return PSW_ASC_SECONDARY;
>>> +    case MMU_HOME_IDX:
>>> +        return PSW_ASC_HOME;
>>> +    default:
>>> +        abort();
>>> +    }
>>> +}
>>> +
>>>   static inline void cpu_get_tb_cpu_state(CPUS390XState* env, target_ulong *pc,
>>>                                           target_ulong *cs_base, uint32_t *flags)
>>>   {
>>> diff --git a/target/s390x/excp_helper.c b/target/s390x/excp_helper.c
>>> index ce16af394b..44bff27f8f 100644
>>> --- a/target/s390x/excp_helper.c
>>> +++ b/target/s390x/excp_helper.c
>>> @@ -105,20 +105,6 @@ bool s390_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
>>>   #else /* !CONFIG_USER_ONLY */
>>> -static inline uint64_t cpu_mmu_idx_to_asc(int mmu_idx)
>>> -{
>>> -    switch (mmu_idx) {
>>> -    case MMU_PRIMARY_IDX:
>>> -        return PSW_ASC_PRIMARY;
>>> -    case MMU_SECONDARY_IDX:
>>> -        return PSW_ASC_SECONDARY;
>>> -    case MMU_HOME_IDX:
>>> -        return PSW_ASC_HOME;
>>> -    default:
>>> -        abort();
>>> -    }
>>> -}
>>> -
>>>   bool s390_cpu_tlb_fill(CPUState *cs, vaddr address, int size,
>>>                          MMUAccessType access_type, int mmu_idx,
>>>                          bool probe, uintptr_t retaddr)
>>> diff --git a/target/s390x/mem_helper.c b/target/s390x/mem_helper.c
>>> index 25cfede806..c7037adf2c 100644
>>> --- a/target/s390x/mem_helper.c
>>> +++ b/target/s390x/mem_helper.c
>>> @@ -855,10 +855,31 @@ uint32_t HELPER(mvpg)(CPUS390XState *env, uint64_t r0, uint64_t r1, uint64_t r2)
>>>       r1 = wrap_address(env, r1 & TARGET_PAGE_MASK);
>>>       r2 = wrap_address(env, r2 & TARGET_PAGE_MASK);
>>> +    /*
>>> +     * If the condition-code-option (CCO) bit is set and DAT is enabled,
>>> +     * we have to check for page table translation faults first:
>>> +     */
>>> +#ifndef CONFIG_USER_ONLY
>>> +    if (extract64(r0, 8, 1) && mmu_idx != MMU_REAL_IDX) {
>>> +        uint64_t asc = cpu_mmu_idx_to_asc(mmu_idx);
>>> +        uint64_t raddr, tec;
>>> +        int flags, exc;
>>> +
>>> +        exc = mmu_translate(env, r2, MMU_DATA_LOAD, asc, &raddr, &flags, &tec);
>>> +        if (exc) {
>>> +            return 2;
>>> +        }
>>> +
>>> +        exc = mmu_translate(env, r1, MMU_DATA_STORE, asc, &raddr, &flags, &tec);
>>> +        if (exc && exc != PGM_PROTECTION) {
>>> +            return 1;
>>> +        }
>>> +    }
>>> +#endif
>>> +
>> This way you always need two additional translations and don't even check if we have something in the TLB. While this works, it's quite inefficient.
>> Using probe_access_flags() we can actually lookup the tlb/fill the tlb but get an error instead of a fault. We could e.g., extent probe_access() to allow specifying whether we want a fault or not.
> 
> I think probe_access_flags() will do all that you need; no further extension to probe_access() required.  I presume you meant access_prepare() is what you meant to extend?

I was worrying about watchpoint handling etc. as done in probe_access().

But I think what you mean is we can simply do two probe_access_flags() to catch these special pgm interrupt, followed by existing access_prepare(). That should work I guess.