swh:1:snp:173f8deb0c56c557784b4fd217e7608ac6197844
Tip revision: dcb7fd82c75ee2d6e6f9d8cc71c52519ed52e258 authored by Linus Torvalds on 05 July 2020, 23:20:22 UTC
Linux 5.8-rc4
Linux 5.8-rc4
Tip revision: dcb7fd8
fault.c
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright 2014 IBM Corp.
*/
#include <linux/workqueue.h>
#include <linux/sched/signal.h>
#include <linux/sched/mm.h>
#include <linux/pid.h>
#include <linux/mm.h>
#include <linux/moduleparam.h>
#undef MODULE_PARAM_PREFIX
#define MODULE_PARAM_PREFIX "cxl" "."
#include <asm/current.h>
#include <asm/copro.h>
#include <asm/mmu.h>
#include "cxl.h"
#include "trace.h"
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, *ret = NULL;
unsigned int mask = (ctx->sst_size >> 7) - 1; /* SSTP0[SegTableSize] */
unsigned int entry;
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;
primary = ctx->sstp + (hash << 3);
for (entry = 0, sste = primary; entry < 8; entry++, 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 */
ret = primary + ctx->sst_lru;
ctx->sst_lru = (ctx->sst_lru + 1) & 0x7;
return ret;
}
static void cxl_load_segment(struct cxl_context *ctx, struct copro_slb *slb)
{
/* mask is the group index, we search primary and secondary here. */
struct cxl_sste *sste;
unsigned long flags;
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);
trace_cxl_ste_write(ctx, sste - ctx->sstp, slb->esid, slb->vsid);
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);
}
static int cxl_fault_segment(struct cxl_context *ctx, struct mm_struct *mm,
u64 ea)
{
struct copro_slb slb = {0,0};
int rc;
if (!(rc = copro_calculate_slb(mm, ea, &slb))) {
cxl_load_segment(ctx, &slb);
}
return rc;
}
static void cxl_ack_ae(struct cxl_context *ctx)
{
unsigned long flags;
cxl_ops->ack_irq(ctx, CXL_PSL_TFC_An_AE, 0);
spin_lock_irqsave(&ctx->lock, flags);
ctx->pending_fault = true;
ctx->fault_addr = ctx->dar;
ctx->fault_dsisr = ctx->dsisr;
spin_unlock_irqrestore(&ctx->lock, flags);
wake_up_all(&ctx->wq);
}
static int cxl_handle_segment_miss(struct cxl_context *ctx,
struct mm_struct *mm, u64 ea)
{
int rc;
pr_devel("CXL interrupt: Segment fault pe: %i ea: %#llx\n", ctx->pe, ea);
trace_cxl_ste_miss(ctx, ea);
if ((rc = cxl_fault_segment(ctx, mm, ea)))
cxl_ack_ae(ctx);
else {
mb(); /* Order seg table write to TFC MMIO write */
cxl_ops->ack_irq(ctx, CXL_PSL_TFC_An_R, 0);
}
return IRQ_HANDLED;
}
int cxl_handle_mm_fault(struct mm_struct *mm, u64 dsisr, u64 dar)
{
vm_fault_t flt = 0;
int result;
unsigned long access, flags, inv_flags = 0;
/*
* Add the fault handling cpu to task mm cpumask so that we
* can do a safe lockless page table walk when inserting the
* hash page table entry. This function get called with a
* valid mm for user space addresses. Hence using the if (mm)
* check is sufficient here.
*/
if (mm && !cpumask_test_cpu(smp_processor_id(), mm_cpumask(mm))) {
cpumask_set_cpu(smp_processor_id(), mm_cpumask(mm));
/*
* We need to make sure we walk the table only after
* we update the cpumask. The other side of the barrier
* is explained in serialize_against_pte_lookup()
*/
smp_mb();
}
if ((result = copro_handle_mm_fault(mm, dar, dsisr, &flt))) {
pr_devel("copro_handle_mm_fault failed: %#x\n", result);
return result;
}
if (!radix_enabled()) {
/*
* update_mmu_cache() will not have loaded the hash since current->trap
* is not a 0x400 or 0x300, so just call hash_page_mm() here.
*/
access = _PAGE_PRESENT | _PAGE_READ;
if (dsisr & CXL_PSL_DSISR_An_S)
access |= _PAGE_WRITE;
if (!mm && (get_region_id(dar) != USER_REGION_ID))
access |= _PAGE_PRIVILEGED;
if (dsisr & DSISR_NOHPTE)
inv_flags |= HPTE_NOHPTE_UPDATE;
local_irq_save(flags);
hash_page_mm(mm, dar, access, 0x300, inv_flags);
local_irq_restore(flags);
}
return 0;
}
static void cxl_handle_page_fault(struct cxl_context *ctx,
struct mm_struct *mm,
u64 dsisr, u64 dar)
{
trace_cxl_pte_miss(ctx, dsisr, dar);
if (cxl_handle_mm_fault(mm, dsisr, dar)) {
cxl_ack_ae(ctx);
} else {
pr_devel("Page fault successfully handled for pe: %i!\n", ctx->pe);
cxl_ops->ack_irq(ctx, CXL_PSL_TFC_An_R, 0);
}
}
/*
* Returns the mm_struct corresponding to the context ctx.
* mm_users == 0, the context may be in the process of being closed.
*/
static struct mm_struct *get_mem_context(struct cxl_context *ctx)
{
if (ctx->mm == NULL)
return NULL;
if (!atomic_inc_not_zero(&ctx->mm->mm_users))
return NULL;
return ctx->mm;
}
static bool cxl_is_segment_miss(struct cxl_context *ctx, u64 dsisr)
{
if ((cxl_is_power8() && (dsisr & CXL_PSL_DSISR_An_DS)))
return true;
return false;
}
static bool cxl_is_page_fault(struct cxl_context *ctx, u64 dsisr)
{
if ((cxl_is_power8()) && (dsisr & CXL_PSL_DSISR_An_DM))
return true;
if (cxl_is_power9())
return true;
return false;
}
void cxl_handle_fault(struct work_struct *fault_work)
{
struct cxl_context *ctx =
container_of(fault_work, struct cxl_context, fault_work);
u64 dsisr = ctx->dsisr;
u64 dar = ctx->dar;
struct mm_struct *mm = NULL;
if (cpu_has_feature(CPU_FTR_HVMODE)) {
if (cxl_p2n_read(ctx->afu, CXL_PSL_DSISR_An) != dsisr ||
cxl_p2n_read(ctx->afu, CXL_PSL_DAR_An) != dar ||
cxl_p2n_read(ctx->afu, CXL_PSL_PEHandle_An) != ctx->pe) {
/* Most likely explanation is harmless - a dedicated
* process has detached and these were cleared by the
* PSL purge, but warn about it just in case
*/
dev_notice(&ctx->afu->dev, "cxl_handle_fault: Translation fault regs changed\n");
return;
}
}
/* Early return if the context is being / has been detached */
if (ctx->status == CLOSED) {
cxl_ack_ae(ctx);
return;
}
pr_devel("CXL BOTTOM HALF handling fault for afu pe: %i. "
"DSISR: %#llx DAR: %#llx\n", ctx->pe, dsisr, dar);
if (!ctx->kernel) {
mm = get_mem_context(ctx);
if (mm == NULL) {
pr_devel("%s: unable to get mm for pe=%d pid=%i\n",
__func__, ctx->pe, pid_nr(ctx->pid));
cxl_ack_ae(ctx);
return;
} else {
pr_devel("Handling page fault for pe=%d pid=%i\n",
ctx->pe, pid_nr(ctx->pid));
}
}
if (cxl_is_segment_miss(ctx, dsisr))
cxl_handle_segment_miss(ctx, mm, dar);
else if (cxl_is_page_fault(ctx, dsisr))
cxl_handle_page_fault(ctx, mm, dsisr, dar);
else
WARN(1, "cxl_handle_fault has nothing to handle\n");
if (mm)
mmput(mm);
}
static void cxl_prefault_one(struct cxl_context *ctx, u64 ea)
{
struct mm_struct *mm;
mm = get_mem_context(ctx);
if (mm == NULL) {
pr_devel("cxl_prefault_one unable to get mm %i\n",
pid_nr(ctx->pid));
return;
}
cxl_fault_segment(ctx, mm, ea);
mmput(mm);
}
static u64 next_segment(u64 ea, u64 vsid)
{
if (vsid & SLB_VSID_B_1T)
ea |= (1ULL << 40) - 1;
else
ea |= (1ULL << 28) - 1;
return ea + 1;
}
static void cxl_prefault_vma(struct cxl_context *ctx)
{
u64 ea, last_esid = 0;
struct copro_slb slb;
struct vm_area_struct *vma;
int rc;
struct mm_struct *mm;
mm = get_mem_context(ctx);
if (mm == NULL) {
pr_devel("cxl_prefault_vm unable to get mm %i\n",
pid_nr(ctx->pid));
return;
}
mmap_read_lock(mm);
for (vma = mm->mmap; vma; vma = vma->vm_next) {
for (ea = vma->vm_start; ea < vma->vm_end;
ea = next_segment(ea, slb.vsid)) {
rc = copro_calculate_slb(mm, ea, &slb);
if (rc)
continue;
if (last_esid == slb.esid)
continue;
cxl_load_segment(ctx, &slb);
last_esid = slb.esid;
}
}
mmap_read_unlock(mm);
mmput(mm);
}
void cxl_prefault(struct cxl_context *ctx, u64 wed)
{
switch (ctx->afu->prefault_mode) {
case CXL_PREFAULT_WED:
cxl_prefault_one(ctx, wed);
break;
case CXL_PREFAULT_ALL:
cxl_prefault_vma(ctx);
break;
default:
break;
}
}