[PATCH V3 04/10] powerpc/mm/hash: Support 68 bit VA
Aneesh Kumar K.V
aneesh.kumar at linux.vnet.ibm.com
Sun Feb 19 21:07:11 AEDT 2017
Inorder to support large effective address range (512TB), we want to increase
the virtual address bits to 68. But we do have platforms like p4 and p5 that can
only do 65 bit VA. We support those platforms by limiting context bits on them
to 16.
The protovsid -> vsid conversion is verified to work with both 65 and 68 bit
va values. I also documented the restrictions in a table format as part of code
comments.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar at linux.vnet.ibm.com>
---
arch/powerpc/include/asm/book3s/64/mmu-hash.h | 123 ++++++++++++++++----------
arch/powerpc/include/asm/mmu.h | 19 ++--
arch/powerpc/kvm/book3s_64_mmu_host.c | 8 +-
arch/powerpc/mm/mmu_context_book3s64.c | 8 +-
arch/powerpc/mm/slb_low.S | 54 +++++++++--
5 files changed, 150 insertions(+), 62 deletions(-)
diff --git a/arch/powerpc/include/asm/book3s/64/mmu-hash.h b/arch/powerpc/include/asm/book3s/64/mmu-hash.h
index 014a9bb197cd..97ccd8ae6c75 100644
--- a/arch/powerpc/include/asm/book3s/64/mmu-hash.h
+++ b/arch/powerpc/include/asm/book3s/64/mmu-hash.h
@@ -39,6 +39,7 @@
/* Bits in the SLB VSID word */
#define SLB_VSID_SHIFT 12
+#define SLB_VSID_SHIFT_256M 12
#define SLB_VSID_SHIFT_1T 24
#define SLB_VSID_SSIZE_SHIFT 62
#define SLB_VSID_B ASM_CONST(0xc000000000000000)
@@ -515,9 +516,19 @@ extern void slb_set_size(u16 size);
* because of the modulo operation in vsid scramble.
*/
+/*
+ * Max Va bits we support as of now is 68 bits. We want 19 bit
+ * context ID.
+ * Restrictions:
+ * GPU has restrictions of not able to access beyond 128TB
+ * (47 bit effective address). We also cannot do more than 20bit PID.
+ * For p4 and p5 which can only do 65 bit VA, we restrict our CONTEXT_BITS
+ * to 16 bits (ie, we can only have 2^16 pids at the same time).
+ */
+#define VA_BITS 68
#define CONTEXT_BITS 19
-#define ESID_BITS 18
-#define ESID_BITS_1T 6
+#define ESID_BITS (VA_BITS - (SID_SHIFT + CONTEXT_BITS))
+#define ESID_BITS_1T (VA_BITS - (SID_SHIFT_1T + CONTEXT_BITS))
#define ESID_BITS_MASK ((1 << ESID_BITS) - 1)
#define ESID_BITS_1T_MASK ((1 << ESID_BITS_1T) - 1)
@@ -526,62 +537,54 @@ extern void slb_set_size(u16 size);
* The proto-VSID space has 2^(CONTEX_BITS + ESID_BITS) - 1 segments
* available for user + kernel mapping. The bottom 4 contexts are used for
* kernel mapping. Each segment contains 2^28 bytes. Each
- * context maps 2^46 bytes (64TB).
+ * context maps 2^49 bytes (512TB).
*
* We also need to avoid the last segment of the last context, because that
* would give a protovsid of 0x1fffffffff. That will result in a VSID 0
* because of the modulo operation in vsid scramble.
*/
#define MAX_USER_CONTEXT ((ASM_CONST(1) << CONTEXT_BITS) - 2)
+/*
+ * For platforms that support on 65bit VA we limit the context bits
+ */
+#define MAX_USER_CONTEXT_65BIT_VA ((ASM_CONST(1) << (65 - (SID_SHIFT + ESID_BITS))) - 2)
/*
* This should be computed such that protovosid * vsid_mulitplier
* doesn't overflow 64 bits. It should also be co-prime to vsid_modulus
+ * We also need to make sure that number of bits in divisor is less
+ * than twice the number of protovsid bits for our modulus optmization to work.
+ * The below table shows the current values used.
+ *
+ * |-------+------------+----------------+------------+--------------|
+ * | | Prime Bits | VSID_BITS_65VA | Total Bits | 2* VSID_BITS |
+ * |-------+------------+----------------+------------+--------------|
+ * | 1T | 24 | 25 | 49 | 50 |
+ * |-------+------------+----------------+------------+--------------|
+ * | 256MB | 24 | 37 | 61 | 74 |
+ * |-------+------------+----------------+------------+--------------|
+ *
+ * |-------+------------+----------------+------------+--------------|
+ * | | Prime Bits | VSID_BITS_68VA | Total Bits | 2* VSID_BITS |
+ * |-------+------------+----------------+------------+--------------|
+ * | 1T | 24 | 28 | 52 | 56 |
+ * |-------+------------+----------------+------------+--------------|
+ * | 256MB | 24 | 40 | 64 | 80 |
+ * |-------+------------+----------------+------------+--------------|
+ *
*/
#define VSID_MULTIPLIER_256M ASM_CONST(12538073) /* 24-bit prime */
-#define VSID_BITS_256M (CONTEXT_BITS + ESID_BITS)
+#define VSID_BITS_256M (VA_BITS - SID_SHIFT)
#define VSID_MODULUS_256M ((1UL<<VSID_BITS_256M)-1)
+#define VSID_BITS_65_256M (65 - SID_SHIFT)
#define VSID_MULTIPLIER_1T ASM_CONST(12538073) /* 24-bit prime */
-#define VSID_BITS_1T (CONTEXT_BITS + ESID_BITS_1T)
+#define VSID_BITS_1T (VA_BITS - SID_SHIFT_1T)
#define VSID_MODULUS_1T ((1UL<<VSID_BITS_1T)-1)
-
+#define VSID_BITS_65_1T (65 - SID_SHIFT_1T)
#define USER_VSID_RANGE (1UL << (ESID_BITS + SID_SHIFT))
-/*
- * This macro generates asm code to compute the VSID scramble
- * function. Used in slb_allocate() and do_stab_bolted. The function
- * computed is: (protovsid*VSID_MULTIPLIER) % VSID_MODULUS
- *
- * rt = register containing the proto-VSID and into which the
- * VSID will be stored
- * rx = scratch register (clobbered)
- *
- * - rt and rx must be different registers
- * - The answer will end up in the low VSID_BITS bits of rt. The higher
- * bits may contain other garbage, so you may need to mask the
- * result.
- */
-#define ASM_VSID_SCRAMBLE(rt, rx, size) \
- lis rx,VSID_MULTIPLIER_##size at h; \
- ori rx,rx,VSID_MULTIPLIER_##size at l; \
- mulld rt,rt,rx; /* rt = rt * MULTIPLIER */ \
- \
- srdi rx,rt,VSID_BITS_##size; \
- clrldi rt,rt,(64-VSID_BITS_##size); \
- add rt,rt,rx; /* add high and low bits */ \
- /* NOTE: explanation based on VSID_BITS_##size = 36 \
- * Now, r3 == VSID (mod 2^36-1), and lies between 0 and \
- * 2^36-1+2^28-1. That in particular means that if r3 >= \
- * 2^36-1, then r3+1 has the 2^36 bit set. So, if r3+1 has \
- * the bit clear, r3 already has the answer we want, if it \
- * doesn't, the answer is the low 36 bits of r3+1. So in all \
- * cases the answer is the low 36 bits of (r3 + ((r3+1) >> 36))*/\
- addi rx,rt,1; \
- srdi rx,rx,VSID_BITS_##size; /* extract 2^VSID_BITS bit */ \
- add rt,rt,rx
-
/* 4 bits per slice and we have one slice per 1TB */
#define SLICE_ARRAY_SIZE (H_PGTABLE_RANGE >> 41)
@@ -629,7 +632,7 @@ static inline void subpage_prot_init_new_context(struct mm_struct *mm) { }
#define vsid_scramble(protovsid, size) \
((((protovsid) * VSID_MULTIPLIER_##size) % VSID_MODULUS_##size))
-#else /* 1 */
+/* simplified form avoiding mod operation */
#define vsid_scramble(protovsid, size) \
({ \
unsigned long x; \
@@ -637,6 +640,21 @@ static inline void subpage_prot_init_new_context(struct mm_struct *mm) { }
x = (x >> VSID_BITS_##size) + (x & VSID_MODULUS_##size); \
(x + ((x+1) >> VSID_BITS_##size)) & VSID_MODULUS_##size; \
})
+
+#else /* 1 */
+static inline unsigned long vsid_scramble(unsigned long protovsid,
+ unsigned long vsid_multiplier, int vsid_bits)
+{
+ unsigned long vsid;
+ unsigned long vsid_modulus = ((1UL << vsid_bits) - 1);
+ /*
+ * We have same multipler for both 256 and 1T segements now
+ */
+ vsid = protovsid * vsid_multiplier;
+ vsid = (vsid >> vsid_bits) + (vsid & vsid_modulus);
+ return (vsid + ((vsid + 1) >> vsid_bits)) & vsid_modulus;
+}
+
#endif /* 1 */
/* Returns the segment size indicator for a user address */
@@ -651,17 +669,32 @@ static inline int user_segment_size(unsigned long addr)
static inline unsigned long get_vsid(unsigned long context, unsigned long ea,
int ssize)
{
+ unsigned long va_bits = VA_BITS;
+ unsigned long vsid_bits;
+ unsigned long protovsid;
+
/*
* Bad address. We return VSID 0 for that
*/
if ((ea & ~REGION_MASK) >= H_PGTABLE_RANGE)
return 0;
- if (ssize == MMU_SEGSIZE_256M)
- return vsid_scramble((context << ESID_BITS)
- | ((ea >> SID_SHIFT) & ESID_BITS_MASK), 256M);
- return vsid_scramble((context << ESID_BITS_1T)
- | ((ea >> SID_SHIFT_1T) & ESID_BITS_1T_MASK), 1T);
+ if (!mmu_has_feature(MMU_FTR_68_BIT_VA))
+ va_bits = 65;
+
+ if (ssize == MMU_SEGSIZE_256M) {
+ vsid_bits = va_bits - SID_SHIFT;
+ protovsid = (context << ESID_BITS) |
+ ((ea >> SID_SHIFT) & ESID_BITS_MASK);
+ return vsid_scramble(protovsid,
+ VSID_MULTIPLIER_256M, vsid_bits);
+ }
+ /* 1T segment */
+ vsid_bits = va_bits - SID_SHIFT_1T;
+ protovsid = (context << ESID_BITS_1T) |
+ ((ea >> SID_SHIFT_1T) & ESID_BITS_1T_MASK);
+ return vsid_scramble(protovsid,
+ VSID_MULTIPLIER_1T, vsid_bits);
}
/*
diff --git a/arch/powerpc/include/asm/mmu.h b/arch/powerpc/include/asm/mmu.h
index 065e762fae85..78260409dc9c 100644
--- a/arch/powerpc/include/asm/mmu.h
+++ b/arch/powerpc/include/asm/mmu.h
@@ -29,6 +29,10 @@
*/
/*
+ * Support for 68 bit VA space. We added that from ISA 2.05
+ */
+#define MMU_FTR_68_BIT_VA ASM_CONST(0x00002000)
+/*
* Kernel read only support.
* We added the ppp value 0b110 in ISA 2.04.
*/
@@ -109,10 +113,10 @@
#define MMU_FTRS_POWER4 MMU_FTRS_DEFAULT_HPTE_ARCH_V2
#define MMU_FTRS_PPC970 MMU_FTRS_POWER4 | MMU_FTR_TLBIE_CROP_VA
#define MMU_FTRS_POWER5 MMU_FTRS_POWER4 | MMU_FTR_LOCKLESS_TLBIE
-#define MMU_FTRS_POWER6 MMU_FTRS_POWER4 | MMU_FTR_LOCKLESS_TLBIE | MMU_FTR_KERNEL_RO
-#define MMU_FTRS_POWER7 MMU_FTRS_POWER4 | MMU_FTR_LOCKLESS_TLBIE | MMU_FTR_KERNEL_RO
-#define MMU_FTRS_POWER8 MMU_FTRS_POWER4 | MMU_FTR_LOCKLESS_TLBIE | MMU_FTR_KERNEL_RO
-#define MMU_FTRS_POWER9 MMU_FTRS_POWER4 | MMU_FTR_LOCKLESS_TLBIE | MMU_FTR_KERNEL_RO
+#define MMU_FTRS_POWER6 MMU_FTRS_POWER5 | MMU_FTR_KERNEL_RO | MMU_FTR_68_BIT_VA
+#define MMU_FTRS_POWER7 MMU_FTRS_POWER6
+#define MMU_FTRS_POWER8 MMU_FTRS_POWER6
+#define MMU_FTRS_POWER9 MMU_FTRS_POWER6
#define MMU_FTRS_CELL MMU_FTRS_DEFAULT_HPTE_ARCH_V2 | \
MMU_FTR_CI_LARGE_PAGE
#define MMU_FTRS_PA6T MMU_FTRS_DEFAULT_HPTE_ARCH_V2 | \
@@ -136,7 +140,7 @@ enum {
MMU_FTR_NO_SLBIE_B | MMU_FTR_16M_PAGE | MMU_FTR_TLBIEL |
MMU_FTR_LOCKLESS_TLBIE | MMU_FTR_CI_LARGE_PAGE |
MMU_FTR_1T_SEGMENT | MMU_FTR_TLBIE_CROP_VA |
- MMU_FTR_KERNEL_RO |
+ MMU_FTR_KERNEL_RO | MMU_FTR_68_BIT_VA |
#ifdef CONFIG_PPC_RADIX_MMU
MMU_FTR_TYPE_RADIX |
#endif
@@ -290,7 +294,10 @@ static inline bool early_radix_enabled(void)
#define MMU_PAGE_16G 14
#define MMU_PAGE_64G 15
-/* N.B. we need to change the type of hpte_page_sizes if this gets to be > 16 */
+/*
+ * N.B. we need to change the type of hpte_page_sizes if this gets to be > 16
+ * Also we need to change he type of mm_context.low/high_slices_psize.
+ */
#define MMU_PAGE_COUNT 16
#ifdef CONFIG_PPC_BOOK3S_64
diff --git a/arch/powerpc/kvm/book3s_64_mmu_host.c b/arch/powerpc/kvm/book3s_64_mmu_host.c
index d6041101a5e2..bed699ab7654 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_host.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_host.c
@@ -229,6 +229,7 @@ void kvmppc_mmu_unmap_page(struct kvm_vcpu *vcpu, struct kvmppc_pte *pte)
static struct kvmppc_sid_map *create_sid_map(struct kvm_vcpu *vcpu, u64 gvsid)
{
+ unsigned long vsid_bits = VSID_BITS_65_256M;
struct kvmppc_sid_map *map;
struct kvmppc_vcpu_book3s *vcpu_book3s = to_book3s(vcpu);
u16 sid_map_mask;
@@ -257,7 +258,12 @@ static struct kvmppc_sid_map *create_sid_map(struct kvm_vcpu *vcpu, u64 gvsid)
kvmppc_mmu_pte_flush(vcpu, 0, 0);
kvmppc_mmu_flush_segments(vcpu);
}
- map->host_vsid = vsid_scramble(vcpu_book3s->proto_vsid_next++, 256M);
+
+ if (mmu_has_feature(MMU_FTR_68_BIT_VA))
+ vsid_bits = VSID_BITS_256M;
+
+ map->host_vsid = vsid_scramble(vcpu_book3s->proto_vsid_next++,
+ VSID_MULTIPLIER_256M, vsid_bits);
map->guest_vsid = gvsid;
map->valid = true;
diff --git a/arch/powerpc/mm/mmu_context_book3s64.c b/arch/powerpc/mm/mmu_context_book3s64.c
index a6450c7f9cf3..e6a5bcbf8abe 100644
--- a/arch/powerpc/mm/mmu_context_book3s64.c
+++ b/arch/powerpc/mm/mmu_context_book3s64.c
@@ -33,6 +33,12 @@ static DEFINE_IDA(mmu_context_ida);
int hash__get_new_context(void)
{
int index, err;
+ unsigned long max_user_context;
+
+ if (mmu_has_feature(MMU_FTR_68_BIT_VA))
+ max_user_context = MAX_USER_CONTEXT;
+ else
+ max_user_context = MAX_USER_CONTEXT_65BIT_VA;
again:
if (!ida_pre_get(&mmu_context_ida, GFP_KERNEL))
@@ -50,7 +56,7 @@ int hash__get_new_context(void)
else if (err)
return err;
- if (index > MAX_USER_CONTEXT) {
+ if (index > max_user_context) {
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 4ce050ea4200..bb75a667483e 100644
--- a/arch/powerpc/mm/slb_low.S
+++ b/arch/powerpc/mm/slb_low.S
@@ -23,6 +23,48 @@
#include <asm/pgtable.h>
#include <asm/firmware.h>
+/*
+ * This macro generates asm code to compute the VSID scramble
+ * function. Used in slb_allocate() and do_stab_bolted. The function
+ * computed is: (protovsid*VSID_MULTIPLIER) % VSID_MODULUS
+ *
+ * rt = register containing the proto-VSID and into which the
+ * VSID will be stored
+ * rx = scratch register (clobbered)
+ * rf = flags
+ *
+ * - rt and rx must be different registers
+ * - The answer will end up in the low VSID_BITS bits of rt. The higher
+ * bits may contain other garbage, so you may need to mask the
+ * result.
+ */
+#define ASM_VSID_SCRAMBLE(rt, rx, rf, size) \
+ lis rx,VSID_MULTIPLIER_##size at h; \
+ ori rx,rx,VSID_MULTIPLIER_##size at l; \
+ mulld rt,rt,rx; /* rt = rt * MULTIPLIER */ \
+/* \
+ * powermac get slb fault before feature fixup, so make 65 bit part \
+ * the default part of feature fixup \
+ */ \
+BEGIN_MMU_FTR_SECTION \
+ srdi rx,rt,VSID_BITS_65_##size; \
+ clrldi rt,rt,(64-VSID_BITS_65_##size); \
+ add rt,rt,rx; \
+ addi rx,rt,1; \
+ srdi rx,rx,VSID_BITS_65_##size; \
+ add rt,rt,rx; \
+ rldimi rf,rt,SLB_VSID_SHIFT_##size,(64 - (SLB_VSID_SHIFT_##size + VSID_BITS_65_##size)); \
+MMU_FTR_SECTION_ELSE \
+ srdi rx,rt,VSID_BITS_##size; \
+ clrldi rt,rt,(64-VSID_BITS_##size); \
+ add rt,rt,rx; /* add high and low bits */ \
+ addi rx,rt,1; \
+ srdi rx,rx,VSID_BITS_##size; /* extract 2^VSID_BITS bit */ \
+ add rt,rt,rx; \
+ rldimi rf,rt,SLB_VSID_SHIFT_##size,(64 - (SLB_VSID_SHIFT_##size + VSID_BITS_##size)); \
+ALT_MMU_FTR_SECTION_END_IFCLR(MMU_FTR_68_BIT_VA)
+
+
/* void slb_allocate_realmode(unsigned long ea);
*
* Create an SLB entry for the given EA (user or kernel).
@@ -179,13 +221,7 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_1T_SEGMENT)
*/
slb_finish_load:
rldimi r10,r9,ESID_BITS,0
- ASM_VSID_SCRAMBLE(r10,r9,256M)
- /*
- * bits above VSID_BITS_256M need to be ignored from r10
- * also combine VSID and flags
- */
- rldimi r11,r10,SLB_VSID_SHIFT,(64 - (SLB_VSID_SHIFT + VSID_BITS_256M))
-
+ ASM_VSID_SCRAMBLE(r10,r9,r11,256M)
/* r3 = EA, r11 = VSID data */
/*
* Find a slot, round robin. Previously we tried to find a
@@ -249,12 +285,12 @@ slb_compare_rr_to_size:
slb_finish_load_1T:
srdi r10,r10,(SID_SHIFT_1T - SID_SHIFT) /* get 1T ESID */
rldimi r10,r9,ESID_BITS_1T,0
- ASM_VSID_SCRAMBLE(r10,r9,1T)
+ ASM_VSID_SCRAMBLE(r10,r9,r11,1T)
/*
* bits above VSID_BITS_1T need to be ignored from r10
* also combine VSID and flags
*/
- rldimi r11,r10,SLB_VSID_SHIFT_1T,(64 - (SLB_VSID_SHIFT_1T + VSID_BITS_1T))
+
li r10,MMU_SEGSIZE_1T
rldimi r11,r10,SLB_VSID_SSIZE_SHIFT,0 /* insert segment size */
--
2.7.4
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