From 5100a9d6444bf205de49190431b0d08de43b86e9 Mon Sep 17 00:00:00 2001 From: Ian Munsie Date: Tue, 28 Oct 2014 14:25:27 +1100 Subject: cxl: Disable secondary hash in segment table This patch simplifies the process of finding a free segment table entry by disabling the secondary hash. This reduces the number of possible entries in the segment table for a given address from 16 to 8. Due to the large segment sizes we use it is extremely unlikely that the secondary hash would ever have been used in practice, so this should not have any negative impacts and may even improve performance due to the reduced number of comparisons that software & hardware need to perform. This patch clears the SC bit in the hardware's state register (CXL_PSL_SR_An) to disable the secondary hash in the hardware since we can no longer fill out entries using it. Signed-off-by: Ian Munsie Reviewed-by: Aneesh Kumar K.V Signed-off-by: Michael Ellerman --- drivers/misc/cxl/fault.c | 30 ++++++++---------------------- drivers/misc/cxl/native.c | 4 ++-- 2 files changed, 10 insertions(+), 24 deletions(-) (limited to 'drivers') diff --git a/drivers/misc/cxl/fault.c b/drivers/misc/cxl/fault.c index 69506ebd4d07..d0e97fd3d4c5 100644 --- a/drivers/misc/cxl/fault.c +++ b/drivers/misc/cxl/fault.c @@ -22,29 +22,19 @@ #include "cxl.h" static struct cxl_sste* find_free_sste(struct cxl_sste *primary_group, - bool sec_hash, - struct cxl_sste *secondary_group, unsigned int *lru) { - unsigned int i, entry; + unsigned int entry; struct cxl_sste *sste, *group = primary_group; - for (i = 0; i < 2; i++) { - for (entry = 0; entry < 8; entry++) { - sste = group + entry; - if (!(be64_to_cpu(sste->esid_data) & SLB_ESID_V)) - return sste; - } - if (!sec_hash) - break; - group = secondary_group; + for (entry = 0; entry < 8; entry++) { + sste = group + entry; + if (!(be64_to_cpu(sste->esid_data) & SLB_ESID_V)) + return sste; } /* Nothing free, select an entry to cast out */ - if (sec_hash && (*lru & 0x8)) - sste = secondary_group + (*lru & 0x7); - else - sste = primary_group + (*lru & 0x7); - *lru = (*lru + 1) & 0xf; + sste = primary_group + *lru; + *lru = (*lru + 1) & 0x7; return sste; } @@ -53,22 +43,18 @@ static void cxl_load_segment(struct cxl_context *ctx, struct copro_slb *slb) { /* mask is the group index, we search primary and secondary here. */ unsigned int mask = (ctx->sst_size >> 7)-1; /* SSTP0[SegTableSize] */ - bool sec_hash = 1; struct cxl_sste *sste; unsigned int hash; unsigned long flags; - sec_hash = !!(cxl_p1n_read(ctx->afu, CXL_PSL_SR_An) & CXL_PSL_SR_An_SC); - if (slb->vsid & SLB_VSID_B_1T) hash = (slb->esid >> SID_SHIFT_1T) & mask; else /* 256M */ hash = (slb->esid >> SID_SHIFT) & mask; spin_lock_irqsave(&ctx->sste_lock, flags); - sste = find_free_sste(ctx->sstp + (hash << 3), sec_hash, - ctx->sstp + ((~hash & mask) << 3), &ctx->sst_lru); + sste = find_free_sste(ctx->sstp + (hash << 3), &ctx->sst_lru); pr_devel("CXL Populating SST[%li]: %#llx %#llx\n", sste - ctx->sstp, slb->vsid, slb->esid); diff --git a/drivers/misc/cxl/native.c b/drivers/misc/cxl/native.c index 623286a77114..d47532e8f4f1 100644 --- a/drivers/misc/cxl/native.c +++ b/drivers/misc/cxl/native.c @@ -417,7 +417,7 @@ static int attach_afu_directed(struct cxl_context *ctx, u64 wed, u64 amr) ctx->elem->haurp = 0; /* disable */ ctx->elem->sdr = cpu_to_be64(mfspr(SPRN_SDR1)); - sr = CXL_PSL_SR_An_SC; + sr = 0; if (ctx->master) sr |= CXL_PSL_SR_An_MP; if (mfspr(SPRN_LPCR) & LPCR_TC) @@ -508,7 +508,7 @@ static int attach_dedicated(struct cxl_context *ctx, u64 wed, u64 amr) u64 sr; int rc; - sr = CXL_PSL_SR_An_SC; + sr = 0; set_endian(sr); if (ctx->master) sr |= CXL_PSL_SR_An_MP; -- cgit v1.2.3 From b03a7f578ac831276fe3870ebda01609d18167de Mon Sep 17 00:00:00 2001 From: Ian Munsie Date: Tue, 28 Oct 2014 14:25:28 +1100 Subject: cxl: Refactor cxl_load_segment() and find_free_sste() This moves the segment table hash calculation from cxl_load_segment() into find_free_sste() since that is the only place it is actually used. Signed-off-by: Ian Munsie Reviewed-by: Aneesh Kumar K.V Signed-off-by: Michael Ellerman --- drivers/misc/cxl/fault.c | 34 ++++++++++++++++++---------------- 1 file changed, 18 insertions(+), 16 deletions(-) (limited to 'drivers') diff --git a/drivers/misc/cxl/fault.c b/drivers/misc/cxl/fault.c index d0e97fd3d4c5..cb4f3231b451 100644 --- a/drivers/misc/cxl/fault.c +++ b/drivers/misc/cxl/fault.c @@ -21,20 +21,30 @@ #include "cxl.h" -static struct cxl_sste* find_free_sste(struct cxl_sste *primary_group, - unsigned int *lru) +/* This finds a free SSTE for the given SLB */ +static struct cxl_sste* find_free_sste(struct cxl_context *ctx, + struct copro_slb *slb) { + struct cxl_sste *primary, *sste; + unsigned int mask = (ctx->sst_size >> 7) - 1; /* SSTP0[SegTableSize] */ unsigned int entry; - struct cxl_sste *sste, *group = primary_group; + unsigned int hash; + + if (slb->vsid & SLB_VSID_B_1T) + hash = (slb->esid >> SID_SHIFT_1T) & mask; + else /* 256M */ + hash = (slb->esid >> SID_SHIFT) & mask; - for (entry = 0; entry < 8; entry++) { - sste = group + entry; + primary = ctx->sstp + (hash << 3); + + for (entry = 0, sste = primary; entry < 8; entry++, sste++) { if (!(be64_to_cpu(sste->esid_data) & SLB_ESID_V)) return sste; } + /* Nothing free, select an entry to cast out */ - sste = primary_group + *lru; - *lru = (*lru + 1) & 0x7; + sste = primary + ctx->sst_lru; + ctx->sst_lru = (ctx->sst_lru + 1) & 0x7; return sste; } @@ -42,19 +52,11 @@ static struct cxl_sste* find_free_sste(struct cxl_sste *primary_group, static void cxl_load_segment(struct cxl_context *ctx, struct copro_slb *slb) { /* mask is the group index, we search primary and secondary here. */ - unsigned int mask = (ctx->sst_size >> 7)-1; /* SSTP0[SegTableSize] */ struct cxl_sste *sste; - unsigned int hash; unsigned long flags; - - if (slb->vsid & SLB_VSID_B_1T) - hash = (slb->esid >> SID_SHIFT_1T) & mask; - else /* 256M */ - hash = (slb->esid >> SID_SHIFT) & mask; - spin_lock_irqsave(&ctx->sste_lock, flags); - sste = find_free_sste(ctx->sstp + (hash << 3), &ctx->sst_lru); + sste = find_free_sste(ctx, slb); pr_devel("CXL Populating SST[%li]: %#llx %#llx\n", sste - ctx->sstp, slb->vsid, slb->esid); -- cgit v1.2.3 From eb01d4c2388ce3b5bcc120d0f72912117ed7599d Mon Sep 17 00:00:00 2001 From: Ian Munsie Date: Tue, 28 Oct 2014 14:25:30 +1100 Subject: cxl: Fix PSL error due to duplicate segment table entries In certain circumstances the PSL (Power Service Layer, which provides translation services for CXL hardware) can send an interrupt for a segment miss that the kernel has already handled. This can happen if multiple translations for the same segment are queued in the PSL before the kernel has restarted the first translation. The CXL driver does not expect this situation and does not check if a segment had already been handled. This could cause a duplicate segment table entry which in turn caused a PSL error taking down the card. This patch fixes the issue by checking for existing entries in the segment table that match the segment we are trying to insert, so as to avoid inserting duplicate entries. Signed-off-by: Ian Munsie Reviewed-by: Aneesh Kumar K.V Signed-off-by: Michael Ellerman --- drivers/misc/cxl/fault.c | 28 ++++++++++++++++++++++------ 1 file changed, 22 insertions(+), 6 deletions(-) (limited to 'drivers') diff --git a/drivers/misc/cxl/fault.c b/drivers/misc/cxl/fault.c index cb4f3231b451..c99e896604ee 100644 --- a/drivers/misc/cxl/fault.c +++ b/drivers/misc/cxl/fault.c @@ -21,11 +21,20 @@ #include "cxl.h" -/* This finds a free SSTE for the given SLB */ +static bool sste_matches(struct cxl_sste *sste, struct copro_slb *slb) +{ + return ((sste->vsid_data == cpu_to_be64(slb->vsid)) && + (sste->esid_data == cpu_to_be64(slb->esid))); +} + +/* + * This finds a free SSTE for the given SLB, or returns NULL if it's already in + * the segment table. + */ static struct cxl_sste* find_free_sste(struct cxl_context *ctx, struct copro_slb *slb) { - struct cxl_sste *primary, *sste; + struct cxl_sste *primary, *sste, *ret = NULL; unsigned int mask = (ctx->sst_size >> 7) - 1; /* SSTP0[SegTableSize] */ unsigned int entry; unsigned int hash; @@ -38,15 +47,19 @@ static struct cxl_sste* find_free_sste(struct cxl_context *ctx, primary = ctx->sstp + (hash << 3); for (entry = 0, sste = primary; entry < 8; entry++, sste++) { - if (!(be64_to_cpu(sste->esid_data) & SLB_ESID_V)) - return sste; + if (!ret && !(be64_to_cpu(sste->esid_data) & SLB_ESID_V)) + ret = sste; + if (sste_matches(sste, slb)) + return NULL; } + if (ret) + return ret; /* Nothing free, select an entry to cast out */ - sste = primary + ctx->sst_lru; + ret = primary + ctx->sst_lru; ctx->sst_lru = (ctx->sst_lru + 1) & 0x7; - return sste; + return ret; } static void cxl_load_segment(struct cxl_context *ctx, struct copro_slb *slb) @@ -57,12 +70,15 @@ static void cxl_load_segment(struct cxl_context *ctx, struct copro_slb *slb) spin_lock_irqsave(&ctx->sste_lock, flags); sste = find_free_sste(ctx, slb); + if (!sste) + goto out_unlock; pr_devel("CXL Populating SST[%li]: %#llx %#llx\n", sste - ctx->sstp, slb->vsid, slb->esid); sste->vsid_data = cpu_to_be64(slb->vsid); sste->esid_data = cpu_to_be64(slb->esid); +out_unlock: spin_unlock_irqrestore(&ctx->sste_lock, flags); } -- cgit v1.2.3