From eb01d4c2388ce3b5bcc120d0f72912117ed7599d Mon Sep 17 00:00:00 2001 From: Ian Munsie Date: Tue, 28 Oct 2014 14:25:30 +1100 Subject: [PATCH] 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(-) 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); }