[PATCH v5 13/26] powerpc/book3s64/pkeys: Enable MMU_FTR_PKEY
Aneesh Kumar K.V
aneesh.kumar at linux.ibm.com
Tue Jul 7 00:09:49 AEST 2020
On 7/6/20 6:40 PM, Michael Ellerman wrote:
> "Aneesh Kumar K.V" <aneesh.kumar at linux.ibm.com> writes:
>> Parse storage keys related device tree entry in early_init_devtree
>> and enable MMU feature MMU_FTR_PKEY if pkeys are supported.
>>
>> MMU feature is used instead of CPU feature because this enables us
>> to group MMU_FTR_KUAP and MMU_FTR_PKEY in asm feature fixup code.
>
> Subject should probably be "Add MMU_FTR_PKEY".
>
>> diff --git a/arch/powerpc/include/asm/mmu.h b/arch/powerpc/include/asm/mmu.h
>> index f4ac25d4df05..72966d3d8f64 100644
>> --- a/arch/powerpc/include/asm/mmu.h
>> +++ b/arch/powerpc/include/asm/mmu.h
>> @@ -23,6 +23,7 @@
>>
>> /* Radix page table supported and enabled */
>> #define MMU_FTR_TYPE_RADIX ASM_CONST(0x00000040)
>> +#define MMU_FTR_PKEY ASM_CONST(0x00000080)
>
> It's not a type, so it should be with the individual feature bits below:
>
We don't have free bit in the other group. For now i will move this to
modified arch/powerpc/include/asm/mmu.h
@@ -23,12 +23,15 @@
/* Radix page table supported and enabled */
#define MMU_FTR_TYPE_RADIX ASM_CONST(0x00000040)
-#define MMU_FTR_PKEY ASM_CONST(0x00000080)
/*
* Individual features below.
*/
+/*
+ * Support for memory protection keys.
+ */
+#define MMU_FTR_PKEY ASM_CONST(0x00001000)
/*
* Support for 68 bit VA space. We added that from ISA 2.05
*/
>> /*
>> * Individual features below.
>
>> diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
>> index 6a3bac357e24..6d70797352d8 100644
>> --- a/arch/powerpc/kernel/prom.c
>> +++ b/arch/powerpc/kernel/prom.c
>> @@ -815,6 +815,11 @@ void __init early_init_devtree(void *params)
>> /* Now try to figure out if we are running on LPAR and so on */
>> pseries_probe_fw_features();
>>
>> + /*
>> + * Initialize pkey features and default AMR/IAMR values
>> + */
>> + pkey_early_init_devtree();
>
> Not your fault, but the fact that we're having to do more and more
> initialisation this early, based on the flat device tree, makes me
> wonder if we need to rethink how we're doing the CPU/MMU feature setup.
>
>> diff --git a/arch/powerpc/mm/book3s64/pkeys.c b/arch/powerpc/mm/book3s64/pkeys.c
>> index 0ff59acdbb84..bbba9c601e14 100644
>> --- a/arch/powerpc/mm/book3s64/pkeys.c
>> +++ b/arch/powerpc/mm/book3s64/pkeys.c
>> @@ -38,38 +39,45 @@ static int execute_only_key = 2;
>> #define PKEY_REG_BITS (sizeof(u64) * 8)
>> #define pkeyshift(pkey) (PKEY_REG_BITS - ((pkey+1) * AMR_BITS_PER_PKEY))
>>
>> +static int __init dt_scan_storage_keys(unsigned long node,
>> + const char *uname, int depth,
>> + void *data)
>> +{
>> + const char *type = of_get_flat_dt_prop(node, "device_type", NULL);
>> + const __be32 *prop;
>> + int pkeys_total;
>> +
>> + /* We are scanning "cpu" nodes only */
>> + if (type == NULL || strcmp(type, "cpu") != 0)
>> + return 0;
>> +
>> + prop = of_get_flat_dt_prop(node, "ibm,processor-storage-keys", NULL);
>> + if (!prop)
>> + return 0;
>> + pkeys_total = be32_to_cpu(prop[0]);
>> + return pkeys_total;
>
> That's not really the way the return value is meant to be used for these
> scanning functions.
>
> The usual return values are 0 to keep scanning and !0 means we've found
> the node we're looking for and we should stop scanning.
>
> Doing it this way means if you find 0 pkeys it will keep scanning.
>
> Instead you should pass &pkeys_total as the data pointer and set that.
>
>> +}
>> +
done
modified arch/powerpc/mm/book3s64/pkeys.c
@@ -52,7 +52,7 @@ static int __init dt_scan_storage_keys(unsigned long node,
{
const char *type = of_get_flat_dt_prop(node, "device_type", NULL);
const __be32 *prop;
- int pkeys_total;
+ int *pkeys_total = (int *) data;
/* We are scanning "cpu" nodes only */
if (type == NULL || strcmp(type, "cpu") != 0)
@@ -61,12 +61,13 @@ static int __init dt_scan_storage_keys(unsigned long
node,
prop = of_get_flat_dt_prop(node, "ibm,processor-storage-keys", NULL);
if (!prop)
return 0;
- pkeys_total = be32_to_cpu(prop[0]);
- return pkeys_total;
+ *pkeys_total = be32_to_cpu(prop[0]);
+ return 1;
}
static int scan_pkey_feature(void)
{
+ int ret;
int pkeys_total;
/*
@@ -75,8 +76,8 @@ static int scan_pkey_feature(void)
if (early_radix_enabled())
return 0;
- pkeys_total = of_scan_flat_dt(dt_scan_storage_keys, NULL);
- if (pkeys_total == 0) {
+ ret = of_scan_flat_dt(dt_scan_storage_keys, &pkeys_total);
+ if (ret == 0) {
/*
* Let's assume 32 pkeys on P8/P9 bare metal, if its not defined by
device
@@ -87,7 +88,6 @@ static int scan_pkey_feature(void)
(early_cpu_has_feature(CPU_FTR_ARCH_207S) ||
early_cpu_has_feature(CPU_FTR_ARCH_300)))
pkeys_total = 32;
-
}
/*
>> static int scan_pkey_feature(void)
>> {
>> - u32 vals[2];
>> - int pkeys_total = 0;
>> - struct device_node *cpu;
>> + int pkeys_total;
>>
>> /*
>> * Pkey is not supported with Radix translation.
>> */
>> - if (radix_enabled())
>> + if (early_radix_enabled())
>> return 0;
>>
>> - cpu = of_find_node_by_type(NULL, "cpu");
>> - if (!cpu)
>> - return 0;
>> + pkeys_total = of_scan_flat_dt(dt_scan_storage_keys, NULL);
>> + if (pkeys_total == 0) {
>>
>> - if (of_property_read_u32_array(cpu,
>> - "ibm,processor-storage-keys", vals, 2) == 0) {
>> - /*
>> - * Since any pkey can be used for data or execute, we will
>> - * just treat all keys as equal and track them as one entity.
>> - */
>> - pkeys_total = vals[0];
>> - /* Should we check for IAMR support FIXME!! */
>
> ???
The device tree allows us to have different count for both AMR and IAMR.
The current code skip that. I guess i added a comment in earlier patch
to check that whether we need to handle different AMR and IAMR counts.
The same comment get dropped here.
>
>> - } else {
>
> This loses the ability to differentiate between no storage-keys property
> at all vs a property that specifies zero keys, which I don't think is a
> good change.
>
>> /*
>> * Let's assume 32 pkeys on P8 bare metal, if its not defined by device
>> * tree. We make this exception since skiboot forgot to expose this
>> * property on power8.
>> */
>> if (!firmware_has_feature(FW_FEATURE_LPAR) &&
>> - cpu_has_feature(CPU_FTRS_POWER8))
>> + early_cpu_has_feature(CPU_FTRS_POWER8))
>> pkeys_total = 32;
>
> That's not how cpu_has_feature() works, we'll need to fix that.
>
> cheers
>
I did a separate patch to handle that which switch the above to
/*
* Let's assume 32 pkeys on P8/P9 bare metal, if its not defined by device
* tree. We make this exception since skiboot forgot to expose this
* property on power8/9.
*/
if (!firmware_has_feature(FW_FEATURE_LPAR) &&
(early_cpu_has_feature(CPU_FTR_ARCH_207S) ||
early_cpu_has_feature(CPU_FTR_ARCH_300)))
pkeys_total = 32;
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