2020-04-02 18:49:35

by David Hildenbrand

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Subject: [PATCH v1 5/5] KVM: s390: vsie: gmap_table_walk() simplifications

---

Let's use asce_type where applicable. Also, simplify our sanity check for
valid table levels and convert it into a WARN_ON_ONCE(). Check if we even
have a valid gmap shadow as the very first step.

Signed-off-by: David Hildenbrand <[email protected]>
---
arch/s390/mm/gmap.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index fd32ab566f57..3c801dae7988 100644
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -790,17 +790,18 @@ static inline unsigned long *gmap_table_walk(struct gmap *gmap,
const int asce_type = gmap->asce & _ASCE_TYPE_MASK;
unsigned long *table;

- if ((gmap->asce & _ASCE_TYPE_MASK) + 4 < (level * 4))
- return NULL;
if (gmap_is_shadow(gmap) && gmap->removed)
return NULL;

+ if (WARN_ON_ONCE(level > (asce_type >> 2) + 1))
+ return NULL;
+
if (WARN_ON_ONCE(asce_type != _ASCE_TYPE_REGION1) &&
gaddr & (-1UL << (31 + (asce_type >> 2) * 11)))
return NULL;

table = gmap->table;
- switch (gmap->asce & _ASCE_TYPE_MASK) {
+ switch (asce_type) {
case _ASCE_TYPE_REGION1:
table += (gaddr & _REGION1_INDEX) >> _REGION1_SHIFT;
if (level == 4)
--
2.25.1

2020-04-03 13:06:48

by Janosch Frank

[permalink] [raw]

Subject: Re: [PATCH v1 5/5] KVM: s390: vsie: gmap_table_walk() simplifications

---

On 4/2/20 8:48 PM, David Hildenbrand wrote:
> Let's use asce_type where applicable. Also, simplify our sanity check for
> valid table levels and convert it into a WARN_ON_ONCE(). Check if we even
> have a valid gmap shadow as the very first step.
>
> Signed-off-by: David Hildenbrand <[email protected]>
> ---
> arch/s390/mm/gmap.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
> index fd32ab566f57..3c801dae7988 100644
> --- a/arch/s390/mm/gmap.c
> +++ b/arch/s390/mm/gmap.c
> @@ -790,17 +790,18 @@ static inline unsigned long *gmap_table_walk(struct gmap *gmap,
> const int asce_type = gmap->asce & _ASCE_TYPE_MASK;
> unsigned long *table;
>
> - if ((gmap->asce & _ASCE_TYPE_MASK) + 4 < (level * 4))
> - return NULL;
> if (gmap_is_shadow(gmap) && gmap->removed)
> return NULL;
>
> + if (WARN_ON_ONCE(level > (asce_type >> 2) + 1))
> + return NULL;
> +
> if (WARN_ON_ONCE(asce_type != _ASCE_TYPE_REGION1) &&
> gaddr & (-1UL << (31 + (asce_type >> 2) * 11)))
> return NULL;
>
> table = gmap->table;

We could also initialize this variable at the top, no?

> - switch (gmap->asce & _ASCE_TYPE_MASK) {
> + switch (asce_type) {
> case _ASCE_TYPE_REGION1:
> table += (gaddr & _REGION1_INDEX) >> _REGION1_SHIFT;
> if (level == 4)
>

---

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2020-04-03 13:11:16

by David Hildenbrand

[permalink] [raw]

Subject: Re: [PATCH v1 5/5] KVM: s390: vsie: gmap_table_walk() simplifications

---

On 03.04.20 15:03, Janosch Frank wrote:
> On 4/2/20 8:48 PM, David Hildenbrand wrote:
>> Let's use asce_type where applicable. Also, simplify our sanity check for
>> valid table levels and convert it into a WARN_ON_ONCE(). Check if we even
>> have a valid gmap shadow as the very first step.
>>
>> Signed-off-by: David Hildenbrand <[email protected]>
>> ---
>> arch/s390/mm/gmap.c | 7 ++++---
>> 1 file changed, 4 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
>> index fd32ab566f57..3c801dae7988 100644
>> --- a/arch/s390/mm/gmap.c
>> +++ b/arch/s390/mm/gmap.c
>> @@ -790,17 +790,18 @@ static inline unsigned long *gmap_table_walk(struct gmap *gmap,
>> const int asce_type = gmap->asce & _ASCE_TYPE_MASK;
>> unsigned long *table;
>>
>> - if ((gmap->asce & _ASCE_TYPE_MASK) + 4 < (level * 4))
>> - return NULL;
>> if (gmap_is_shadow(gmap) && gmap->removed)
>> return NULL;
>>
>> + if (WARN_ON_ONCE(level > (asce_type >> 2) + 1))
>> + return NULL;
>> +
>> if (WARN_ON_ONCE(asce_type != _ASCE_TYPE_REGION1) &&
>> gaddr & (-1UL << (31 + (asce_type >> 2) * 11)))
>> return NULL;
>>
>> table = gmap->table;
>
> We could also initialize this variable at the top, no?

very right, add that.


--
Thanks,

David / dhildenb