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[v3] target/s390x: Implement the MVPG condition-code-option bit

Message ID 20210303024423.3125722-1-richard.henderson@linaro.org
State New
Headers show
Series [v3] target/s390x: Implement the MVPG condition-code-option bit | expand

Commit Message

Richard Henderson March 3, 2021, 2:44 a.m. UTC
If the CCO bit is set, MVPG should not generate an exception but
report page translation faults via a CC code.

Create a new helper, access_prepare_nf, which can use probe_access_flags
in non-faulting mode, and then handle watchpoints.

Cc: David Hildenbrand <david@redhat.com>
Reported-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/s390x/mem_helper.c | 87 ++++++++++++++++++++++++++++-----------
 1 file changed, 64 insertions(+), 23 deletions(-)

Comments

Thomas Huth March 3, 2021, 6:25 a.m. UTC | #1
On 03/03/2021 03.44, Richard Henderson wrote:
> If the CCO bit is set, MVPG should not generate an exception but
> report page translation faults via a CC code.
> 
> Create a new helper, access_prepare_nf, which can use probe_access_flags
> in non-faulting mode, and then handle watchpoints.
> 
> Cc: David Hildenbrand <david@redhat.com>
> Reported-by: Thomas Huth <thuth@redhat.com>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>   target/s390x/mem_helper.c | 87 ++++++++++++++++++++++++++++-----------
>   1 file changed, 64 insertions(+), 23 deletions(-)
> 
> diff --git a/target/s390x/mem_helper.c b/target/s390x/mem_helper.c
> index 25cfede806..b397333c0b 100644
> --- a/target/s390x/mem_helper.c
> +++ b/target/s390x/mem_helper.c
> @@ -130,28 +130,62 @@ typedef struct S390Access {
>       int mmu_idx;
>   } S390Access;
>   
> +static bool access_prepare_nf(S390Access *access, CPUS390XState *env,
> +                              bool nofault, vaddr vaddr1, int size,
> +                              MMUAccessType access_type,
> +                              int mmu_idx, uintptr_t ra)
> +{
> +    void *haddr1, *haddr2 = NULL;
> +    int size1, size2;
> +    vaddr vaddr2 = 0;
> +    int flags;
> +
> +    assert(size > 0 && size <= 4096);
> +
> +    size1 = MIN(size, -(vaddr1 | TARGET_PAGE_MASK)),
> +    size2 = size - size1;
> +
> +    flags = probe_access_flags(env, vaddr1, access_type, mmu_idx,
> +                               nofault, &haddr1, ra);
> +    if (unlikely(size2)) {
> +        /* The access crosses page boundaries. */
> +        vaddr2 = wrap_address(env, vaddr1 + size1);
> +        flags |= probe_access_flags(env, vaddr2, access_type, mmu_idx,
> +                                    nofault, &haddr2, ra);
> +    }
> +
> +    if (unlikely(flags & TLB_INVALID_MASK)) {
> +        return false;
> +    }
> +    if (unlikely(flags & TLB_WATCHPOINT)) {
> +        /* S390 does not presently use transaction attributes. */
> +        cpu_check_watchpoint(env_cpu(env), vaddr1, size,
> +                             MEMTXATTRS_UNSPECIFIED,
> +                             (access_type == MMU_DATA_STORE
> +                              ? BP_MEM_WRITE : BP_MEM_READ), ra);
> +    }
> +
> +    *access = (S390Access) {
> +        .vaddr1 = vaddr1,
> +        .vaddr2 = vaddr2,
> +        .haddr1 = haddr1,
> +        .haddr2 = haddr2,
> +        .size1 = size1,
> +        .size2 = size2,
> +        .mmu_idx = mmu_idx
> +    };
> +    return true;
> +}
> +
>   static S390Access access_prepare(CPUS390XState *env, vaddr vaddr, int size,
>                                    MMUAccessType access_type, int mmu_idx,
>                                    uintptr_t ra)
>   {
> -    S390Access access = {
> -        .vaddr1 = vaddr,
> -        .size1 = MIN(size, -(vaddr | TARGET_PAGE_MASK)),
> -        .mmu_idx = mmu_idx,
> -    };
> -
> -    g_assert(size > 0 && size <= 4096);
> -    access.haddr1 = probe_access(env, access.vaddr1, access.size1, access_type,
> -                                 mmu_idx, ra);
> -
> -    if (unlikely(access.size1 != size)) {
> -        /* The access crosses page boundaries. */
> -        access.vaddr2 = wrap_address(env, vaddr + access.size1);
> -        access.size2 = size - access.size1;
> -        access.haddr2 = probe_access(env, access.vaddr2, access.size2,
> -                                     access_type, mmu_idx, ra);
> -    }
> -    return access;
> +    S390Access ret;
> +    bool ok = access_prepare_nf(&ret, env, false, vaddr, size,
> +                                access_type, mmu_idx, ra);
> +    assert(ok);
> +    return ret;
>   }
>   
>   /* Helper to handle memset on a single page. */
> @@ -845,8 +879,10 @@ uint32_t HELPER(mvpg)(CPUS390XState *env, uint64_t r0, uint64_t r1, uint64_t r2)
>       const int mmu_idx = cpu_mmu_index(env, false);
>       const bool f = extract64(r0, 11, 1);
>       const bool s = extract64(r0, 10, 1);
> +    const bool cco = extract64(r0, 8, 1);
>       uintptr_t ra = GETPC();
>       S390Access srca, desta;
> +    bool ok;
>   
>       if ((f && s) || extract64(r0, 12, 4)) {
>           tcg_s390_program_interrupt(env, PGM_SPECIFICATION, GETPC());
> @@ -858,13 +894,18 @@ uint32_t HELPER(mvpg)(CPUS390XState *env, uint64_t r0, uint64_t r1, uint64_t r2)
>       /*
>        * 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,
> -                          ra);
> -    desta = access_prepare(env, r1, TARGET_PAGE_SIZE, MMU_DATA_STORE, mmu_idx,
> -                           ra);
> +    ok = access_prepare_nf(&srca, env, cco, r2, TARGET_PAGE_SIZE,
> +                           MMU_DATA_LOAD, mmu_idx, ra);
> +    if (!ok) {
> +        return 2;
> +    }
> +    ok = access_prepare_nf(&desta, env, cco, r1, TARGET_PAGE_SIZE,
> +                           MMU_DATA_STORE, mmu_idx, ra);
> +    if (!ok) {
> +        return 1;
> +    }

Thanks, this looks promising, but one of the MVPG kvm-unit-tests is still 
failing with this patch - the one that checks for an exception if the 
destination page is marked as read-only. MVPG only returns CC1 for invalid 
page table entries - but if the page is write-protected, it still causes a 
protection exception. That's why I've been checking "if (exc && exc != 
PGM_PROTECTION)" in my version of the patch.

  Thomas
Thomas Huth March 3, 2021, 11:36 a.m. UTC | #2
On 03/03/2021 07.25, Thomas Huth wrote:
> On 03/03/2021 03.44, Richard Henderson wrote:
>> If the CCO bit is set, MVPG should not generate an exception but
>> report page translation faults via a CC code.
>>
>> Create a new helper, access_prepare_nf, which can use probe_access_flags
>> in non-faulting mode, and then handle watchpoints.
>>
>> Cc: David Hildenbrand <david@redhat.com>
>> Reported-by: Thomas Huth <thuth@redhat.com>
>> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
>> ---
>>   target/s390x/mem_helper.c | 87 ++++++++++++++++++++++++++++-----------
>>   1 file changed, 64 insertions(+), 23 deletions(-)
>>
>> diff --git a/target/s390x/mem_helper.c b/target/s390x/mem_helper.c
>> index 25cfede806..b397333c0b 100644
>> --- a/target/s390x/mem_helper.c
>> +++ b/target/s390x/mem_helper.c
>> @@ -130,28 +130,62 @@ typedef struct S390Access {
>>       int mmu_idx;
>>   } S390Access;
>> +static bool access_prepare_nf(S390Access *access, CPUS390XState *env,
>> +                              bool nofault, vaddr vaddr1, int size,
>> +                              MMUAccessType access_type,
>> +                              int mmu_idx, uintptr_t ra)
>> +{
>> +    void *haddr1, *haddr2 = NULL;
>> +    int size1, size2;
>> +    vaddr vaddr2 = 0;
>> +    int flags;
>> +
>> +    assert(size > 0 && size <= 4096);
>> +
>> +    size1 = MIN(size, -(vaddr1 | TARGET_PAGE_MASK)),
>> +    size2 = size - size1;
>> +
>> +    flags = probe_access_flags(env, vaddr1, access_type, mmu_idx,
>> +                               nofault, &haddr1, ra);
>> +    if (unlikely(size2)) {
>> +        /* The access crosses page boundaries. */
>> +        vaddr2 = wrap_address(env, vaddr1 + size1);
>> +        flags |= probe_access_flags(env, vaddr2, access_type, mmu_idx,
>> +                                    nofault, &haddr2, ra);
>> +    }
>> +
>> +    if (unlikely(flags & TLB_INVALID_MASK)) {
>> +        return false;
>> +    }
>> +    if (unlikely(flags & TLB_WATCHPOINT)) {
>> +        /* S390 does not presently use transaction attributes. */
>> +        cpu_check_watchpoint(env_cpu(env), vaddr1, size,
>> +                             MEMTXATTRS_UNSPECIFIED,
>> +                             (access_type == MMU_DATA_STORE
>> +                              ? BP_MEM_WRITE : BP_MEM_READ), ra);
>> +    }
>> +
>> +    *access = (S390Access) {
>> +        .vaddr1 = vaddr1,
>> +        .vaddr2 = vaddr2,
>> +        .haddr1 = haddr1,
>> +        .haddr2 = haddr2,
>> +        .size1 = size1,
>> +        .size2 = size2,
>> +        .mmu_idx = mmu_idx
>> +    };
>> +    return true;
>> +}
>> +
>>   static S390Access access_prepare(CPUS390XState *env, vaddr vaddr, int size,
>>                                    MMUAccessType access_type, int mmu_idx,
>>                                    uintptr_t ra)
>>   {
>> -    S390Access access = {
>> -        .vaddr1 = vaddr,
>> -        .size1 = MIN(size, -(vaddr | TARGET_PAGE_MASK)),
>> -        .mmu_idx = mmu_idx,
>> -    };
>> -
>> -    g_assert(size > 0 && size <= 4096);
>> -    access.haddr1 = probe_access(env, access.vaddr1, access.size1, 
>> access_type,
>> -                                 mmu_idx, ra);
>> -
>> -    if (unlikely(access.size1 != size)) {
>> -        /* The access crosses page boundaries. */
>> -        access.vaddr2 = wrap_address(env, vaddr + access.size1);
>> -        access.size2 = size - access.size1;
>> -        access.haddr2 = probe_access(env, access.vaddr2, access.size2,
>> -                                     access_type, mmu_idx, ra);
>> -    }
>> -    return access;
>> +    S390Access ret;
>> +    bool ok = access_prepare_nf(&ret, env, false, vaddr, size,
>> +                                access_type, mmu_idx, ra);
>> +    assert(ok);
>> +    return ret;
>>   }
>>   /* Helper to handle memset on a single page. */
>> @@ -845,8 +879,10 @@ uint32_t HELPER(mvpg)(CPUS390XState *env, uint64_t 
>> r0, uint64_t r1, uint64_t r2)
>>       const int mmu_idx = cpu_mmu_index(env, false);
>>       const bool f = extract64(r0, 11, 1);
>>       const bool s = extract64(r0, 10, 1);
>> +    const bool cco = extract64(r0, 8, 1);
>>       uintptr_t ra = GETPC();
>>       S390Access srca, desta;
>> +    bool ok;
>>       if ((f && s) || extract64(r0, 12, 4)) {
>>           tcg_s390_program_interrupt(env, PGM_SPECIFICATION, GETPC());
>> @@ -858,13 +894,18 @@ uint32_t HELPER(mvpg)(CPUS390XState *env, uint64_t 
>> r0, uint64_t r1, uint64_t r2)
>>       /*
>>        * 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,
>> -                          ra);
>> -    desta = access_prepare(env, r1, TARGET_PAGE_SIZE, MMU_DATA_STORE, 
>> mmu_idx,
>> -                           ra);
>> +    ok = access_prepare_nf(&srca, env, cco, r2, TARGET_PAGE_SIZE,
>> +                           MMU_DATA_LOAD, mmu_idx, ra);
>> +    if (!ok) {
>> +        return 2;
>> +    }
>> +    ok = access_prepare_nf(&desta, env, cco, r1, TARGET_PAGE_SIZE,
>> +                           MMU_DATA_STORE, mmu_idx, ra);
>> +    if (!ok) {
>> +        return 1;
>> +    }
> 
> Thanks, this looks promising, but one of the MVPG kvm-unit-tests is still 
> failing with this patch - the one that checks for an exception if the 
> destination page is marked as read-only. MVPG only returns CC1 for invalid 
> page table entries - but if the page is write-protected, it still causes a 
> protection exception. That's why I've been checking "if (exc && exc != 
> PGM_PROTECTION)" in my version of the patch.

FWIW, I can get the MVPG kvm-unit-test working with your patch if I add
this on top:

diff a/target/s390x/mem_helper.c b/target/s390x/mem_helper.c
--- a/target/s390x/mem_helper.c
+++ b/target/s390x/mem_helper.c
@@ -904,7 +904,14 @@ uint32_t HELPER(mvpg)(CPUS390XState *env, uint64_t r0, uint64_t r1, uint64_t r2)
      ok = access_prepare_nf(&desta, env, cco, r1, TARGET_PAGE_SIZE,
                             MMU_DATA_STORE, mmu_idx, ra);
      if (!ok) {
-        return 1;
+        ok = access_prepare_nf(&desta, env, cco, r1, TARGET_PAGE_SIZE,
+                               MMU_DATA_LOAD, mmu_idx, ra);
+        if (!ok) {
+            return 1;
+        }
+        /* If reading was ok, then the page must be protected. */
+        /* TODO: Set a translation exception code in lowcore? */
+        tcg_s390_program_interrupt(env, PGM_PROTECTION, ra);
      }
      access_memmove(env, &desta, &srca, ra);
      return 0; /* data moved */

... yeah, it's ugly to call access_prepare_nf() again with MMU_DATA_LOAD,
and it's still missing the translation exception code ... but at least
the kvm-unit-test is happy that way...

  Thomas
David Hildenbrand March 3, 2021, 11:40 a.m. UTC | #3
On 03.03.21 12:36, Thomas Huth wrote:
> On 03/03/2021 07.25, Thomas Huth wrote:
>> On 03/03/2021 03.44, Richard Henderson wrote:
>>> If the CCO bit is set, MVPG should not generate an exception but
>>> report page translation faults via a CC code.
>>>
>>> Create a new helper, access_prepare_nf, which can use probe_access_flags
>>> in non-faulting mode, and then handle watchpoints.
>>>
>>> Cc: David Hildenbrand <david@redhat.com>
>>> Reported-by: Thomas Huth <thuth@redhat.com>
>>> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
>>> ---
>>>    target/s390x/mem_helper.c | 87 ++++++++++++++++++++++++++++-----------
>>>    1 file changed, 64 insertions(+), 23 deletions(-)
>>>
>>> diff --git a/target/s390x/mem_helper.c b/target/s390x/mem_helper.c
>>> index 25cfede806..b397333c0b 100644
>>> --- a/target/s390x/mem_helper.c
>>> +++ b/target/s390x/mem_helper.c
>>> @@ -130,28 +130,62 @@ typedef struct S390Access {
>>>        int mmu_idx;
>>>    } S390Access;
>>> +static bool access_prepare_nf(S390Access *access, CPUS390XState *env,
>>> +                              bool nofault, vaddr vaddr1, int size,
>>> +                              MMUAccessType access_type,
>>> +                              int mmu_idx, uintptr_t ra)
>>> +{
>>> +    void *haddr1, *haddr2 = NULL;
>>> +    int size1, size2;
>>> +    vaddr vaddr2 = 0;
>>> +    int flags;
>>> +
>>> +    assert(size > 0 && size <= 4096);
>>> +
>>> +    size1 = MIN(size, -(vaddr1 | TARGET_PAGE_MASK)),
>>> +    size2 = size - size1;
>>> +
>>> +    flags = probe_access_flags(env, vaddr1, access_type, mmu_idx,
>>> +                               nofault, &haddr1, ra);
>>> +    if (unlikely(size2)) {
>>> +        /* The access crosses page boundaries. */
>>> +        vaddr2 = wrap_address(env, vaddr1 + size1);
>>> +        flags |= probe_access_flags(env, vaddr2, access_type, mmu_idx,
>>> +                                    nofault, &haddr2, ra);
>>> +    }
>>> +
>>> +    if (unlikely(flags & TLB_INVALID_MASK)) {
>>> +        return false;
>>> +    }
>>> +    if (unlikely(flags & TLB_WATCHPOINT)) {
>>> +        /* S390 does not presently use transaction attributes. */
>>> +        cpu_check_watchpoint(env_cpu(env), vaddr1, size,
>>> +                             MEMTXATTRS_UNSPECIFIED,
>>> +                             (access_type == MMU_DATA_STORE
>>> +                              ? BP_MEM_WRITE : BP_MEM_READ), ra);
>>> +    }
>>> +
>>> +    *access = (S390Access) {
>>> +        .vaddr1 = vaddr1,
>>> +        .vaddr2 = vaddr2,
>>> +        .haddr1 = haddr1,
>>> +        .haddr2 = haddr2,
>>> +        .size1 = size1,
>>> +        .size2 = size2,
>>> +        .mmu_idx = mmu_idx
>>> +    };
>>> +    return true;
>>> +}
>>> +
>>>    static S390Access access_prepare(CPUS390XState *env, vaddr vaddr, int size,
>>>                                     MMUAccessType access_type, int mmu_idx,
>>>                                     uintptr_t ra)
>>>    {
>>> -    S390Access access = {
>>> -        .vaddr1 = vaddr,
>>> -        .size1 = MIN(size, -(vaddr | TARGET_PAGE_MASK)),
>>> -        .mmu_idx = mmu_idx,
>>> -    };
>>> -
>>> -    g_assert(size > 0 && size <= 4096);
>>> -    access.haddr1 = probe_access(env, access.vaddr1, access.size1,
>>> access_type,
>>> -                                 mmu_idx, ra);
>>> -
>>> -    if (unlikely(access.size1 != size)) {
>>> -        /* The access crosses page boundaries. */
>>> -        access.vaddr2 = wrap_address(env, vaddr + access.size1);
>>> -        access.size2 = size - access.size1;
>>> -        access.haddr2 = probe_access(env, access.vaddr2, access.size2,
>>> -                                     access_type, mmu_idx, ra);
>>> -    }
>>> -    return access;
>>> +    S390Access ret;
>>> +    bool ok = access_prepare_nf(&ret, env, false, vaddr, size,
>>> +                                access_type, mmu_idx, ra);
>>> +    assert(ok);
>>> +    return ret;
>>>    }
>>>    /* Helper to handle memset on a single page. */
>>> @@ -845,8 +879,10 @@ uint32_t HELPER(mvpg)(CPUS390XState *env, uint64_t
>>> r0, uint64_t r1, uint64_t r2)
>>>        const int mmu_idx = cpu_mmu_index(env, false);
>>>        const bool f = extract64(r0, 11, 1);
>>>        const bool s = extract64(r0, 10, 1);
>>> +    const bool cco = extract64(r0, 8, 1);
>>>        uintptr_t ra = GETPC();
>>>        S390Access srca, desta;
>>> +    bool ok;
>>>        if ((f && s) || extract64(r0, 12, 4)) {
>>>            tcg_s390_program_interrupt(env, PGM_SPECIFICATION, GETPC());
>>> @@ -858,13 +894,18 @@ uint32_t HELPER(mvpg)(CPUS390XState *env, uint64_t
>>> r0, uint64_t r1, uint64_t r2)
>>>        /*
>>>         * 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,
>>> -                          ra);
>>> -    desta = access_prepare(env, r1, TARGET_PAGE_SIZE, MMU_DATA_STORE,
>>> mmu_idx,
>>> -                           ra);
>>> +    ok = access_prepare_nf(&srca, env, cco, r2, TARGET_PAGE_SIZE,
>>> +                           MMU_DATA_LOAD, mmu_idx, ra);
>>> +    if (!ok) {
>>> +        return 2;
>>> +    }
>>> +    ok = access_prepare_nf(&desta, env, cco, r1, TARGET_PAGE_SIZE,
>>> +                           MMU_DATA_STORE, mmu_idx, ra);
>>> +    if (!ok) {
>>> +        return 1;
>>> +    }
>>
>> Thanks, this looks promising, but one of the MVPG kvm-unit-tests is still
>> failing with this patch - the one that checks for an exception if the
>> destination page is marked as read-only. MVPG only returns CC1 for invalid
>> page table entries - but if the page is write-protected, it still causes a
>> protection exception. That's why I've been checking "if (exc && exc !=
>> PGM_PROTECTION)" in my version of the patch.
> 
> FWIW, I can get the MVPG kvm-unit-test working with your patch if I add
> this on top:
> 
> diff a/target/s390x/mem_helper.c b/target/s390x/mem_helper.c
> --- a/target/s390x/mem_helper.c
> +++ b/target/s390x/mem_helper.c
> @@ -904,7 +904,14 @@ uint32_t HELPER(mvpg)(CPUS390XState *env, uint64_t r0, uint64_t r1, uint64_t r2)
>        ok = access_prepare_nf(&desta, env, cco, r1, TARGET_PAGE_SIZE,
>                               MMU_DATA_STORE, mmu_idx, ra);
>        if (!ok) {
> -        return 1;
> +        ok = access_prepare_nf(&desta, env, cco, r1, TARGET_PAGE_SIZE,
> +                               MMU_DATA_LOAD, mmu_idx, ra);
> +        if (!ok) {
> +            return 1;
> +        }
> +        /* If reading was ok, then the page must be protected. */
> +        /* TODO: Set a translation exception code in lowcore? */
> +        tcg_s390_program_interrupt(env, PGM_PROTECTION, ra);
>        }
>        access_memmove(env, &desta, &srca, ra);
>        return 0; /* data moved */
> 
> ... yeah, it's ugly to call access_prepare_nf() again with MMU_DATA_LOAD,
> and it's still missing the translation exception code ... but at least
> the kvm-unit-test is happy that way...

As I said, can't we store the last exception we had during tlb_fill and 
use that in case returns access_prepare_nf() returns an error to 
identify the actual exception?
Thomas Huth March 3, 2021, 12:32 p.m. UTC | #4
On 03/03/2021 12.40, David Hildenbrand wrote:
> On 03.03.21 12:36, Thomas Huth wrote:
>> On 03/03/2021 07.25, Thomas Huth wrote:
>>> On 03/03/2021 03.44, Richard Henderson wrote:
>>>> If the CCO bit is set, MVPG should not generate an exception but
>>>> report page translation faults via a CC code.
>>>>
>>>> Create a new helper, access_prepare_nf, which can use probe_access_flags
>>>> in non-faulting mode, and then handle watchpoints.
>>>>
>>>> Cc: David Hildenbrand <david@redhat.com>
>>>> Reported-by: Thomas Huth <thuth@redhat.com>
>>>> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
>>>> ---
>>>>    target/s390x/mem_helper.c | 87 ++++++++++++++++++++++++++++-----------
>>>>    1 file changed, 64 insertions(+), 23 deletions(-)
>>>>
>>>> diff --git a/target/s390x/mem_helper.c b/target/s390x/mem_helper.c
>>>> index 25cfede806..b397333c0b 100644
>>>> --- a/target/s390x/mem_helper.c
>>>> +++ b/target/s390x/mem_helper.c
>>>> @@ -130,28 +130,62 @@ typedef struct S390Access {
>>>>        int mmu_idx;
>>>>    } S390Access;
>>>> +static bool access_prepare_nf(S390Access *access, CPUS390XState *env,
>>>> +                              bool nofault, vaddr vaddr1, int size,
>>>> +                              MMUAccessType access_type,
>>>> +                              int mmu_idx, uintptr_t ra)
>>>> +{
>>>> +    void *haddr1, *haddr2 = NULL;
>>>> +    int size1, size2;
>>>> +    vaddr vaddr2 = 0;
>>>> +    int flags;
>>>> +
>>>> +    assert(size > 0 && size <= 4096);
>>>> +
>>>> +    size1 = MIN(size, -(vaddr1 | TARGET_PAGE_MASK)),
>>>> +    size2 = size - size1;
>>>> +
>>>> +    flags = probe_access_flags(env, vaddr1, access_type, mmu_idx,
>>>> +                               nofault, &haddr1, ra);
>>>> +    if (unlikely(size2)) {
>>>> +        /* The access crosses page boundaries. */
>>>> +        vaddr2 = wrap_address(env, vaddr1 + size1);
>>>> +        flags |= probe_access_flags(env, vaddr2, access_type, mmu_idx,
>>>> +                                    nofault, &haddr2, ra);
>>>> +    }
>>>> +
>>>> +    if (unlikely(flags & TLB_INVALID_MASK)) {
>>>> +        return false;
>>>> +    }
>>>> +    if (unlikely(flags & TLB_WATCHPOINT)) {
>>>> +        /* S390 does not presently use transaction attributes. */
>>>> +        cpu_check_watchpoint(env_cpu(env), vaddr1, size,
>>>> +                             MEMTXATTRS_UNSPECIFIED,
>>>> +                             (access_type == MMU_DATA_STORE
>>>> +                              ? BP_MEM_WRITE : BP_MEM_READ), ra);
>>>> +    }
>>>> +
>>>> +    *access = (S390Access) {
>>>> +        .vaddr1 = vaddr1,
>>>> +        .vaddr2 = vaddr2,
>>>> +        .haddr1 = haddr1,
>>>> +        .haddr2 = haddr2,
>>>> +        .size1 = size1,
>>>> +        .size2 = size2,
>>>> +        .mmu_idx = mmu_idx
>>>> +    };
>>>> +    return true;
>>>> +}
>>>> +
>>>>    static S390Access access_prepare(CPUS390XState *env, vaddr vaddr, int 
>>>> size,
>>>>                                     MMUAccessType access_type, int mmu_idx,
>>>>                                     uintptr_t ra)
>>>>    {
>>>> -    S390Access access = {
>>>> -        .vaddr1 = vaddr,
>>>> -        .size1 = MIN(size, -(vaddr | TARGET_PAGE_MASK)),
>>>> -        .mmu_idx = mmu_idx,
>>>> -    };
>>>> -
>>>> -    g_assert(size > 0 && size <= 4096);
>>>> -    access.haddr1 = probe_access(env, access.vaddr1, access.size1,
>>>> access_type,
>>>> -                                 mmu_idx, ra);
>>>> -
>>>> -    if (unlikely(access.size1 != size)) {
>>>> -        /* The access crosses page boundaries. */
>>>> -        access.vaddr2 = wrap_address(env, vaddr + access.size1);
>>>> -        access.size2 = size - access.size1;
>>>> -        access.haddr2 = probe_access(env, access.vaddr2, access.size2,
>>>> -                                     access_type, mmu_idx, ra);
>>>> -    }
>>>> -    return access;
>>>> +    S390Access ret;
>>>> +    bool ok = access_prepare_nf(&ret, env, false, vaddr, size,
>>>> +                                access_type, mmu_idx, ra);
>>>> +    assert(ok);
>>>> +    return ret;
>>>>    }
>>>>    /* Helper to handle memset on a single page. */
>>>> @@ -845,8 +879,10 @@ uint32_t HELPER(mvpg)(CPUS390XState *env, uint64_t
>>>> r0, uint64_t r1, uint64_t r2)
>>>>        const int mmu_idx = cpu_mmu_index(env, false);
>>>>        const bool f = extract64(r0, 11, 1);
>>>>        const bool s = extract64(r0, 10, 1);
>>>> +    const bool cco = extract64(r0, 8, 1);
>>>>        uintptr_t ra = GETPC();
>>>>        S390Access srca, desta;
>>>> +    bool ok;
>>>>        if ((f && s) || extract64(r0, 12, 4)) {
>>>>            tcg_s390_program_interrupt(env, PGM_SPECIFICATION, GETPC());
>>>> @@ -858,13 +894,18 @@ uint32_t HELPER(mvpg)(CPUS390XState *env, uint64_t
>>>> r0, uint64_t r1, uint64_t r2)
>>>>        /*
>>>>         * 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,
>>>> -                          ra);
>>>> -    desta = access_prepare(env, r1, TARGET_PAGE_SIZE, MMU_DATA_STORE,
>>>> mmu_idx,
>>>> -                           ra);
>>>> +    ok = access_prepare_nf(&srca, env, cco, r2, TARGET_PAGE_SIZE,
>>>> +                           MMU_DATA_LOAD, mmu_idx, ra);
>>>> +    if (!ok) {
>>>> +        return 2;
>>>> +    }
>>>> +    ok = access_prepare_nf(&desta, env, cco, r1, TARGET_PAGE_SIZE,
>>>> +                           MMU_DATA_STORE, mmu_idx, ra);
>>>> +    if (!ok) {
>>>> +        return 1;
>>>> +    }
>>>
>>> Thanks, this looks promising, but one of the MVPG kvm-unit-tests is still
>>> failing with this patch - the one that checks for an exception if the
>>> destination page is marked as read-only. MVPG only returns CC1 for invalid
>>> page table entries - but if the page is write-protected, it still causes a
>>> protection exception. That's why I've been checking "if (exc && exc !=
>>> PGM_PROTECTION)" in my version of the patch.
>>
>> FWIW, I can get the MVPG kvm-unit-test working with your patch if I add
>> this on top:
>>
>> diff a/target/s390x/mem_helper.c b/target/s390x/mem_helper.c
>> --- a/target/s390x/mem_helper.c
>> +++ b/target/s390x/mem_helper.c
>> @@ -904,7 +904,14 @@ uint32_t HELPER(mvpg)(CPUS390XState *env, uint64_t 
>> r0, uint64_t r1, uint64_t r2)
>>        ok = access_prepare_nf(&desta, env, cco, r1, TARGET_PAGE_SIZE,
>>                               MMU_DATA_STORE, mmu_idx, ra);
>>        if (!ok) {
>> -        return 1;
>> +        ok = access_prepare_nf(&desta, env, cco, r1, TARGET_PAGE_SIZE,
>> +                               MMU_DATA_LOAD, mmu_idx, ra);
>> +        if (!ok) {
>> +            return 1;
>> +        }
>> +        /* If reading was ok, then the page must be protected. */
>> +        /* TODO: Set a translation exception code in lowcore? */
>> +        tcg_s390_program_interrupt(env, PGM_PROTECTION, ra);
>>        }
>>        access_memmove(env, &desta, &srca, ra);
>>        return 0; /* data moved */
>>
>> ... yeah, it's ugly to call access_prepare_nf() again with MMU_DATA_LOAD,
>> and it's still missing the translation exception code ... but at least
>> the kvm-unit-test is happy that way...
> 
> As I said, can't we store the last exception we had during tlb_fill and use 
> that in case returns access_prepare_nf() returns an error to identify the 
> actual exception?

Ah, right, thanks. That's likely the best way to do it. I just gave it a try 
and it seems to work ... I'll send out that modified versions as a v4...

  Thomas
diff mbox series

Patch

diff --git a/target/s390x/mem_helper.c b/target/s390x/mem_helper.c
index 25cfede806..b397333c0b 100644
--- a/target/s390x/mem_helper.c
+++ b/target/s390x/mem_helper.c
@@ -130,28 +130,62 @@  typedef struct S390Access {
     int mmu_idx;
 } S390Access;
 
+static bool access_prepare_nf(S390Access *access, CPUS390XState *env,
+                              bool nofault, vaddr vaddr1, int size,
+                              MMUAccessType access_type,
+                              int mmu_idx, uintptr_t ra)
+{
+    void *haddr1, *haddr2 = NULL;
+    int size1, size2;
+    vaddr vaddr2 = 0;
+    int flags;
+
+    assert(size > 0 && size <= 4096);
+
+    size1 = MIN(size, -(vaddr1 | TARGET_PAGE_MASK)),
+    size2 = size - size1;
+
+    flags = probe_access_flags(env, vaddr1, access_type, mmu_idx,
+                               nofault, &haddr1, ra);
+    if (unlikely(size2)) {
+        /* The access crosses page boundaries. */
+        vaddr2 = wrap_address(env, vaddr1 + size1);
+        flags |= probe_access_flags(env, vaddr2, access_type, mmu_idx,
+                                    nofault, &haddr2, ra);
+    }
+
+    if (unlikely(flags & TLB_INVALID_MASK)) {
+        return false;
+    }
+    if (unlikely(flags & TLB_WATCHPOINT)) {
+        /* S390 does not presently use transaction attributes. */
+        cpu_check_watchpoint(env_cpu(env), vaddr1, size,
+                             MEMTXATTRS_UNSPECIFIED,
+                             (access_type == MMU_DATA_STORE
+                              ? BP_MEM_WRITE : BP_MEM_READ), ra);
+    }
+
+    *access = (S390Access) {
+        .vaddr1 = vaddr1,
+        .vaddr2 = vaddr2,
+        .haddr1 = haddr1,
+        .haddr2 = haddr2,
+        .size1 = size1,
+        .size2 = size2,
+        .mmu_idx = mmu_idx
+    };
+    return true;
+}
+
 static S390Access access_prepare(CPUS390XState *env, vaddr vaddr, int size,
                                  MMUAccessType access_type, int mmu_idx,
                                  uintptr_t ra)
 {
-    S390Access access = {
-        .vaddr1 = vaddr,
-        .size1 = MIN(size, -(vaddr | TARGET_PAGE_MASK)),
-        .mmu_idx = mmu_idx,
-    };
-
-    g_assert(size > 0 && size <= 4096);
-    access.haddr1 = probe_access(env, access.vaddr1, access.size1, access_type,
-                                 mmu_idx, ra);
-
-    if (unlikely(access.size1 != size)) {
-        /* The access crosses page boundaries. */
-        access.vaddr2 = wrap_address(env, vaddr + access.size1);
-        access.size2 = size - access.size1;
-        access.haddr2 = probe_access(env, access.vaddr2, access.size2,
-                                     access_type, mmu_idx, ra);
-    }
-    return access;
+    S390Access ret;
+    bool ok = access_prepare_nf(&ret, env, false, vaddr, size,
+                                access_type, mmu_idx, ra);
+    assert(ok);
+    return ret;
 }
 
 /* Helper to handle memset on a single page. */
@@ -845,8 +879,10 @@  uint32_t HELPER(mvpg)(CPUS390XState *env, uint64_t r0, uint64_t r1, uint64_t r2)
     const int mmu_idx = cpu_mmu_index(env, false);
     const bool f = extract64(r0, 11, 1);
     const bool s = extract64(r0, 10, 1);
+    const bool cco = extract64(r0, 8, 1);
     uintptr_t ra = GETPC();
     S390Access srca, desta;
+    bool ok;
 
     if ((f && s) || extract64(r0, 12, 4)) {
         tcg_s390_program_interrupt(env, PGM_SPECIFICATION, GETPC());
@@ -858,13 +894,18 @@  uint32_t HELPER(mvpg)(CPUS390XState *env, uint64_t r0, uint64_t r1, uint64_t r2)
     /*
      * 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,
-                          ra);
-    desta = access_prepare(env, r1, TARGET_PAGE_SIZE, MMU_DATA_STORE, mmu_idx,
-                           ra);
+    ok = access_prepare_nf(&srca, env, cco, r2, TARGET_PAGE_SIZE,
+                           MMU_DATA_LOAD, mmu_idx, ra);
+    if (!ok) {
+        return 2;
+    }
+    ok = access_prepare_nf(&desta, env, cco, r1, TARGET_PAGE_SIZE,
+                           MMU_DATA_STORE, mmu_idx, ra);
+    if (!ok) {
+        return 1;
+    }
     access_memmove(env, &desta, &srca, ra);
     return 0; /* data moved */
 }