"Aneesh Kumar K.V" <aneesh.ku...@linux.vnet.ibm.com> writes:
> From: "Aneesh Kumar K.V" <aneesh.ku...@linux.vnet.ibm.com>
>
> This patch change the kernel VSID range so that we limit VSID_BITS to 37.
> This enables us to support 64TB with 65 bit VA (37+28). Without this patch
> we have boot hangs on platforms that only support 65 bit VA.
>
> With this patch we now have proto vsid generated as below:
>
> We first generate a 37-bit "proto-VSID". Proto-VSIDs are generated
> from mmu context id and effective segment id of the address.
>
> For user processes max context id is limited to ((1ul << 19) - 6)
> for kernel space, we use the top 4 context ids to map address as below
> 0x7fffb - [ 0xc000000000000000 - 0xcfffffffffffffff ]
> 0x7fffc - [ 0xd000000000000000 - 0xdfffffffffffffff ]
> 0x7fffd - [ 0xe000000000000000 - 0xefffffffffffffff ]
> 0x7fffe - [ 0xf000000000000000 - 0xffffffffffffffff ]
I guess we can do this as below
0x7fffc - [ 0xc000000000000000 - 0xcfffffffffffffff ]
0x7fffd - [ 0xd000000000000000 - 0xdfffffffffffffff ]
0x7fffe - [ 0xe000000000000000 - 0xefffffffffffffff ]
0x7ffff - [ 0xf000000000000000 - 0xffffffffffffffff ]
Will update this as part of next revision after I get full review.
diff --git a/arch/powerpc/include/asm/mmu-hash64.h
b/arch/powerpc/include/asm/mmu-hash64.h
index 3e297ea..71c69e6 100644
--- a/arch/powerpc/include/asm/mmu-hash64.h
+++ b/arch/powerpc/include/asm/mmu-hash64.h
@@ -355,10 +355,10 @@ extern void slb_set_size(u16 size);
*
* For user processes max context id is limited to ((1ul << 19) - 6)
* for kernel space, we use the top 4 context ids to map address as below
- * 0x7fffb - [ 0xc000000000000000 - 0xcfffffffffffffff ]
- * 0x7fffc - [ 0xd000000000000000 - 0xdfffffffffffffff ]
- * 0x7fffd - [ 0xe000000000000000 - 0xefffffffffffffff ]
- * 0x7fffe - [ 0xf000000000000000 - 0xffffffffffffffff ]
+ * 0x7fffc - [ 0xc000000000000000 - 0xcfffffffffffffff ]
+ * 0x7fffd - [ 0xd000000000000000 - 0xdfffffffffffffff ]
+ * 0x7fffe - [ 0xe000000000000000 - 0xefffffffffffffff ]
+ * 0x7ffff - [ 0xf000000000000000 - 0xffffffffffffffff ]
*
* The proto-VSIDs are then scrambled into real VSIDs with the
* multiplicative hash:
@@ -561,10 +561,10 @@ static inline unsigned long get_vsid(unsigned long
context, unsigned long ea,
* This is only valid for addresses >= PAGE_OFFSET
*
* For kernel space, we use the top 4 context ids to map address as below
- * 0x7fffb - [ 0xc000000000000000 - 0xcfffffffffffffff ]
- * 0x7fffc - [ 0xd000000000000000 - 0xdfffffffffffffff ]
- * 0x7fffd - [ 0xe000000000000000 - 0xefffffffffffffff ]
- * 0x7fffe - [ 0xf000000000000000 - 0xffffffffffffffff ]
+ * 0x7fffc - [ 0xc000000000000000 - 0xcfffffffffffffff ]
+ * 0x7fffd - [ 0xd000000000000000 - 0xdfffffffffffffff ]
+ * 0x7fffe - [ 0xe000000000000000 - 0xefffffffffffffff ]
+ * 0x7ffff - [ 0xf000000000000000 - 0xffffffffffffffff ]
*/
static inline unsigned long get_kernel_vsid(unsigned long ea, int ssize)
{
@@ -574,7 +574,7 @@ static inline unsigned long get_kernel_vsid(unsigned long
ea, int ssize)
* kernel take the top 4 context from the available range
*/
c_index = ((ea >> 60) - 0xc);
- context = (MAX_CONTEXT - 4) + c_index;
+ context = (MAX_CONTEXT - 3) + c_index;
#ifdef CONFIG_DEBUG_VM
/*
* Drop the c_index related bits from ea, so we get
diff --git a/arch/powerpc/kernel/exceptions-64s.S
b/arch/powerpc/kernel/exceptions-64s.S
index d8f6804..cb6404b 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -1273,10 +1273,10 @@ _GLOBAL(do_stab_bolted)
/*
* Calculate VSID:
* This is the kernel vsid, we take the top for context from
- * the range. context = (MAX_CONTEXT - 4) + ((ea >> 60) - 0xc)
+ * the range. context = (MAX_CONTEXT - 3) + ((ea >> 60) - 0xc)
*/
srdi r9,r11,60
- subi r9,r9,(0xc + 4 + 1)
+ subi r9,r9,(0xc + 3 + 1)
lis r10,8
add r9,r9,r10 /* context */
diff --git a/arch/powerpc/mm/mmu_context_hash64.c
b/arch/powerpc/mm/mmu_context_hash64.c
index 9c84b16..59cd773 100644
--- a/arch/powerpc/mm/mmu_context_hash64.c
+++ b/arch/powerpc/mm/mmu_context_hash64.c
@@ -48,6 +48,7 @@ again:
return err;
if (index > (MAX_CONTEXT - 4)) {
+ /* Top 4 context id values are used for kernel */
spin_lock(&mmu_context_lock);
ida_remove(&mmu_context_ida, index);
spin_unlock(&mmu_context_lock);
diff --git a/arch/powerpc/mm/slb_low.S b/arch/powerpc/mm/slb_low.S
index 2a233cb..2c9524b 100644
--- a/arch/powerpc/mm/slb_low.S
+++ b/arch/powerpc/mm/slb_low.S
@@ -56,10 +56,10 @@ _GLOBAL(slb_allocate_realmode)
_GLOBAL(slb_miss_kernel_load_linear)
li r11,0
/*
- * context = (MAX_CONTEXT - 4) + ((ea >> 60) - 0xc)
+ * context = (MAX_CONTEXT - 3) + ((ea >> 60) - 0xc)
*/
srdi r9,r3,60
- subi r9,r9,(0xc + 4 + 1)
+ subi r9,r9,(0xc + 3 + 1)
lis r10, 8
add r9,r9,r10
srdi r10,r3,SID_SHIFT /* get esid */
@@ -99,10 +99,10 @@ _GLOBAL(slb_miss_kernel_load_vmemmap)
li r11,0
6:
/*
- * context = (MAX_CONTEXT - 4) + ((ea >> 60) - 0xc)
+ * context = (MAX_CONTEXT - 3) + ((ea >> 60) - 0xc)
*/
srdi r9,r3,60
- subi r9,r9,(0xc + 4 + 1)
+ subi r9,r9,(0xc + 3 + 1)
lis r10,8
add r9,r9,r10
srdi r10,r3,28 /* FIXME!! doing it twice */
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